draft-ietf-mobileip-ipv6-24.txt   rfc3775.txt 
IETF Mobile IP Working Group D. Johnson Network Working Group D. Johnson
Internet-Draft Rice University Request for Comments: 3775 Rice University
Expires: December 29, 2003 C. Perkins Category: Standards Track C. Perkins
Nokia Research Center Nokia Research Center
J. Arkko J. Arkko
Ericsson Ericsson
June 30, 2003 June 2004
Mobility Support in IPv6 Mobility Support in IPv6
draft-ietf-mobileip-ipv6-24.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document specifies an Internet standards track protocol for the
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Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2004).
Abstract Abstract
This document specifies a protocol which allows nodes to remain This document specifies a protocol which allows nodes to remain
reachable while moving around in the IPv6 Internet. Each mobile node reachable while moving around in the IPv6 Internet. Each mobile node
is always identified by its home address, regardless of its current is always identified by its home address, regardless of its current
point of attachment to the Internet. While situated away from its point of attachment to the Internet. While situated away from its
home, a mobile node is also associated with a care-of address, which home, a mobile node is also associated with a care-of address, which
provides information about the mobile node's current location. IPv6 provides information about the mobile node's current location. IPv6
packets addressed to a mobile node's home address are transparently packets addressed to a mobile node's home address are transparently
routed to its care-of address. The protocol enables IPv6 nodes to routed to its care-of address. The protocol enables IPv6 nodes to
cache the binding of a mobile node's home address with its care-of cache the binding of a mobile node's home address with its care-of
address, and to then send any packets destined for the mobile node address, and to then send any packets destined for the mobile node
directly to it at this care-of address. To support this operation, directly to it at this care-of address. To support this operation,
Mobile IPv6 defines a new IPv6 protocol and a new destination option. Mobile IPv6 defines a new IPv6 protocol and a new destination option.
All IPv6 nodes, whether mobile or stationary can communicate with All IPv6 nodes, whether mobile or stationary, can communicate with
mobile nodes. mobile nodes.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 5
2. Comparison with Mobile IP for IPv4 . . . . . . . . . . . . 8 2. Comparison with Mobile IP for IPv4 . . . . . . . . . . . . 6
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 9 3. Terminology. . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 General Terms . . . . . . . . . . . . . . . . . . . 9 3.1. General Terms . . . . . . . . . . . . . . . . . . . 8
3.2 Mobile IPv6 Terms . . . . . . . . . . . . . . . . . 11 3.2. Mobile IPv6 Terms . . . . . . . . . . . . . . . . . 10
4. Overview of Mobile IPv6 . . . . . . . . . . . . . . . . . 15 4. Overview of Mobile IPv6. . . . . . . . . . . . . . . . . . 13
4.1 Basic Operation . . . . . . . . . . . . . . . . . . 15 4.1. Basic Operation . . . . . . . . . . . . . . . . . . 13
4.2 New IPv6 Protocol . . . . . . . . . . . . . . . . . 17 4.2. New IPv6 Protocol . . . . . . . . . . . . . . . . . 15
4.3 New IPv6 Destination Option . . . . . . . . . . . . 18 4.3. New IPv6 Destination Option . . . . . . . . . . . . 17
4.4 New IPv6 ICMP Messages . . . . . . . . . . . . . . . 18 4.4. New IPv6 ICMP Messages. . . . . . . . . . . . . . . 17
4.5 Conceptual Data Structure Terminology . . . . . . . 18 4.5. Conceptual Data Structure Terminology . . . . . . . 17
4.6 Site-Local Addressability . . . . . . . . . . . . . 19 4.6. Site-Local Addressability . . . . . . . . . . . . . 18
5. Overview of Mobile IPv6 Security . . . . . . . . . . . . . 20 5. Overview of Mobile IPv6 Security . . . . . . . . . . . . . 18
5.1 Binding Updates to Home Agents . . . . . . . . . . . 20 5.1. Binding Updates to Home Agents. . . . . . . . . . . 18
5.2 Binding Updates to Correspondent Nodes . . . . . . . 21 5.2. Binding Updates to Correspondent Nodes. . . . . . . 20
5.2.1 Node Keys . . . . . . . . . . . . . . . . . 22 5.2.1. Node Keys . . . . . . . . . . . . . . . . . 20
5.2.2 Nonces . . . . . . . . . . . . . . . . . . . 22 5.2.2. Nonces. . . . . . . . . . . . . . . . . . . 20
5.2.3 Cookies and Tokens . . . . . . . . . . . . . 23 5.2.3. Cookies and Tokens. . . . . . . . . . . . . 21
5.2.4 Cryptographic Functions . . . . . . . . . . 23 5.2.4. Cryptographic Functions . . . . . . . . . . 22
5.2.5 Return Routability Procedure . . . . . . . . 23 5.2.5. Return Routability Procedure. . . . . . . . 22
5.2.6 Authorizing Binding Management Messages . . 28 5.2.6. Authorizing Binding Management Messages . . 27
5.2.7 Updating Node Keys and Nonces . . . . . . . 30 5.2.7. Updating Node Keys and Nonces . . . . . . . 29
5.2.8 Preventing Replay Attacks . . . . . . . . . 31 5.2.8. Preventing Replay Attacks . . . . . . . . . 30
5.3 Dynamic Home Agent Address Discovery . . . . . . . . 31 5.3. Dynamic Home Agent Address Discovery. . . . . . . . 30
5.4 Mobile Prefix Discovery . . . . . . . . . . . . . . 31 5.4. Mobile Prefix Discovery . . . . . . . . . . . . . . 30
5.5 Payload Packets . . . . . . . . . . . . . . . . . . 32 5.5. Payload Packets . . . . . . . . . . . . . . . . . . 30
6. New IPv6 Protocol, Message Types, and Destination Option . 33 6. New IPv6 Protocol, Message Types, and Destination Option . 31
6.1 Mobility Header . . . . . . . . . . . . . . . . . . 33 6.1. Mobility Header . . . . . . . . . . . . . . . . . . 31
6.1.1 Format . . . . . . . . . . . . . . . . . . . 33 6.1.1. Format. . . . . . . . . . . . . . . . . . . 32
6.1.2 Binding Refresh Request Message . . . . . . 35 6.1.2. Binding Refresh Request Message . . . . . . 34
6.1.3 Home Test Init Message . . . . . . . . . . . 36 6.1.3. Home Test Init Message. . . . . . . . . . . 35
6.1.4 Care-of Test Init Message . . . . . . . . . 37 6.1.4. Care-of Test Init Message . . . . . . . . . 36
6.1.5 Home Test Message . . . . . . . . . . . . . 38 6.1.5. Home Test Message . . . . . . . . . . . . . 37
6.1.6 Care-of Test Message . . . . . . . . . . . . 39 6.1.6. Care-of Test Message. . . . . . . . . . . . 38
6.1.7 Binding Update Message . . . . . . . . . . . 41 6.1.7. Binding Update Message. . . . . . . . . . . 39
6.1.8 Binding Acknowledgement Message . . . . . . 43 6.1.8. Binding Acknowledgement Message . . . . . . 42
6.1.9 Binding Error Message . . . . . . . . . . . 46 6.1.9. Binding Error Message . . . . . . . . . . . 44
6.2 Mobility Options . . . . . . . . . . . . . . . . . . 47 6.2. Mobility Options. . . . . . . . . . . . . . . . . . 46
6.2.1 Format . . . . . . . . . . . . . . . . . . . 48 6.2.1. Format. . . . . . . . . . . . . . . . . . . 46
6.2.2 Pad1 . . . . . . . . . . . . . . . . . . . . 48 6.2.2. Pad1. . . . . . . . . . . . . . . . . . . . 47
6.2.3 PadN . . . . . . . . . . . . . . . . . . . . 49 6.2.3. PadN. . . . . . . . . . . . . . . . . . . . 48
6.2.4 Binding Refresh Advice . . . . . . . . . . . 49 6.2.4. Binding Refresh Advice. . . . . . . . . . . 48
6.2.5 Alternate Care-of Address . . . . . . . . . 50 6.2.5. Alternate Care-of Address . . . . . . . . . 49
6.2.6 Nonce Indices . . . . . . . . . . . . . . . 50 6.2.6. Nonce Indices . . . . . . . . . . . . . . . 49
6.2.7 Binding Authorization Data . . . . . . . . . 51 6.2.7. Binding Authorization Data. . . . . . . . . 50
6.3 Home Address Option . . . . . . . . . . . . . . . . 52 6.3. Home Address Option . . . . . . . . . . . . . . . . 51
6.4 Type 2 Routing Header . . . . . . . . . . . . . . . 54 6.4. Type 2 Routing Header . . . . . . . . . . . . . . . 53
6.4.1 Format . . . . . . . . . . . . . . . . . . . 54 6.4.1. Format. . . . . . . . . . . . . . . . . . . 54
6.5 ICMP Home Agent Address Discovery Request Message . 56 6.5. ICMP Home Agent Address Discovery Request Message . 55
6.6 ICMP Home Agent Address Discovery Reply Message . . 57 6.6. ICMP Home Agent Address Discovery Reply Message . . 56
6.7 ICMP Mobile Prefix Solicitation Message Format . . . 58 6.7. ICMP Mobile Prefix Solicitation Message Format. . . 57
6.8 ICMP Mobile Prefix Advertisement Message Format . . 60 6.8. ICMP Mobile Prefix Advertisement Message Format . . 59
7. Modifications to IPv6 Neighbor Discovery . . . . . . . . . 63 7. Modifications to IPv6 Neighbor Discovery . . . . . . . . . 61
7.1 Modified Router Advertisement Message Format . . . . 63 7.1. Modified Router Advertisement Message Format. . . . 61
7.2 Modified Prefix Information Option Format . . . . . 63 7.2. Modified Prefix Information Option Format . . . . . 62
7.3 New Advertisement Interval Option Format . . . . . . 65 7.3. New Advertisement Interval Option Format. . . . . . 64
7.4 New Home Agent Information Option Format . . . . . . 66 7.4. New Home Agent Information Option Format. . . . . . 65
7.5 Changes to Sending Router Advertisements . . . . . . 68 7.5. Changes to Sending Router Advertisements. . . . . . 67
8. Requirements for Types of IPv6 Nodes . . . . . . . . . . . 70 8. Requirements for Types of IPv6 Nodes . . . . . . . . . . . 69
8.1 All IPv6 Nodes . . . . . . . . . . . . . . . . . . . 70 8.1. All IPv6 Nodes. . . . . . . . . . . . . . . . . . . 69
8.2 IPv6 Nodes with Support for Route Optimization . . . 70 8.2. IPv6 Nodes with Support for Route Optimization. . . 69
8.3 All IPv6 Routers . . . . . . . . . . . . . . . . . . 72 8.3. All IPv6 Routers. . . . . . . . . . . . . . . . . . 71
8.4 IPv6 Home Agents . . . . . . . . . . . . . . . . . . 72 8.4. IPv6 Home Agents. . . . . . . . . . . . . . . . . . 71
8.5 IPv6 Mobile Nodes . . . . . . . . . . . . . . . . . 74 8.5. IPv6 Mobile Nodes . . . . . . . . . . . . . . . . . 73
9. Correspondent Node Operation . . . . . . . . . . . . . . . 76 9. Correspondent Node Operation . . . . . . . . . . . . . . . 74
9.1 Conceptual Data Structures . . . . . . . . . . . . . 76 9.1. Conceptual Data Structures. . . . . . . . . . . . . 74
9.2 Processing Mobility Headers . . . . . . . . . . . . 77 9.2. Processing Mobility Headers . . . . . . . . . . . . 75
9.3 Packet Processing . . . . . . . . . . . . . . . . . 77 9.3. Packet Processing . . . . . . . . . . . . . . . . . 76
9.3.1 Receiving Packets with Home Address Option . 77 9.3.1. Receiving Packets with Home Address Option. 76
9.3.2 Sending Packets to a Mobile Node . . . . . . 78 9.3.2. Sending Packets to a Mobile Node. . . . . . 77
9.3.3 Sending Binding Error Messages . . . . . . . 80 9.3.3. Sending Binding Error Messages. . . . . . . 78
9.3.4 Receiving ICMP Error Messages . . . . . . . 80 9.3.4. Receiving ICMP Error Messages . . . . . . . 79
9.4 Return Routability Procedure . . . . . . . . . . . . 81 9.4. Return Routability Procedure. . . . . . . . . . . . 79
9.4.1 Receiving Home Test Init Messages . . . . . 81 9.4.1. Receiving Home Test Init Messages . . . . . 80
9.4.2 Receiving Care-of Test Init Messages . . . . 81 9.4.2. Receiving Care-of Test Init Messages. . . . 80
9.4.3 Sending Home Test Messages . . . . . . . . . 82 9.4.3. Sending Home Test Messages. . . . . . . . . 80
9.4.4 Sending Care-of Test Messages . . . . . . . 82 9.4.4. Sending Care-of Test Messages . . . . . . . 81
9.5 Processing Bindings . . . . . . . . . . . . . . . . 82 9.5 Processing Bindings . . . . . . . . . . . . . . . . 81
9.5.1 Receiving Binding Updates . . . . . . . . . 82 9.5.1. Receiving Binding Updates . . . . . . . . . 81
9.5.2 Requests to Cache a Binding . . . . . . . . 85 9.5.2. Requests to Cache a Binding . . . . . . . . 84
9.5.3 Requests to Delete a Binding . . . . . . . . 85 9.5.3. Requests to Delete a Binding. . . . . . . . 84
9.5.4 Sending Binding Acknowledgements . . . . . . 86 9.5.4. Sending Binding Acknowledgements. . . . . . 85
9.5.5 Sending Binding Refresh Requests . . . . . . 87 9.5.5. Sending Binding Refresh Requests. . . . . . 86
9.6 Cache Replacement Policy . . . . . . . . . . . . . . 87 9.6. Cache Replacement Policy. . . . . . . . . . . . . . 86
10. Home Agent Operation . . . . . . . . . . . . . . . . . . . 89 10. Home Agent Operation . . . . . . . . . . . . . . . . . . . 87
10.1 Conceptual Data Structures . . . . . . . . . . . . . 89 10.1. Conceptual Data Structures. . . . . . . . . . . . . 87
10.2 Processing Mobility Headers . . . . . . . . . . . . 90 10.2. Processing Mobility Headers . . . . . . . . . . . . 88
10.3 Processing Bindings . . . . . . . . . . . . . . . . 90 10.3. Processing Bindings . . . . . . . . . . . . . . . . 88
10.3.1 Primary Care-of Address Registration . . . . 90 10.3.1. Primary Care-of Address Registration. . . . 88
10.3.2 Primary Care-of Address De-Registration . . 94 10.3.2. Primary Care-of Address De-Registration . . 92
10.4 Packet Processing . . . . . . . . . . . . . . . . . 95 10.4. Packet Processing . . . . . . . . . . . . . . . . . 94
10.4.1 Intercepting Packets for a Mobile Node . . . 95 10.4.1. Intercepting Packets for a Mobile Node. . . 94
10.4.2 Processing Intercepted Packets . . . . . . . 97 10.4.2. Processing Intercepted Packets. . . . . . . 95
10.4.3 Multicast Membership Control . . . . . . . . 98 10.4.3. Multicast Membership Control. . . . . . . . 96
10.4.4 Stateful Address Autoconfiguration . . . . . 99 10.4.4. Stateful Address Autoconfiguration. . . . . 98
10.4.5 Handling Reverse Tunneled Packets . . . . . 99 10.4.5. Handling Reverse Tunneled Packets . . . . . 98
10.4.6 Protecting Return Routability Packets . . . 100 10.4.6. Protecting Return Routability Packets . . . 99
10.5 Dynamic Home Agent Address Discovery . . . . . . . .101 10.5. Dynamic Home Agent Address Discovery. . . . . . . . 99
10.5.1 Receiving Router Advertisement Messages . . 101 10.5.1. Receiving Router Advertisement Messages . . 100
10.6 Sending Prefix Information to the Mobile Node . . .103 10.6. Sending Prefix Information to the Mobile Node . . . 102
10.6.1 List of Home Network Prefixes . . . . . . . 103 10.6.1. List of Home Network Prefixes . . . . . . . 102
10.6.2 Scheduling Prefix Deliveries . . . . . . . . 104 10.6.2. Scheduling Prefix Deliveries. . . . . . . . 102
10.6.3 Sending Advertisements . . . . . . . . . . . 106 10.6.3. Sending Advertisements. . . . . . . . . . . 104
10.6.4 Lifetimes for Changed Prefixes . . . . . . . 107 10.6.4. Lifetimes for Changed Prefixes. . . . . . . 105
11. Mobile Node Operation . . . . . . . . . . . . . . . . . . 108 11. Mobile Node Operation. . . . . . . . . . . . . . . . . . . 105
11.1 Conceptual Data Structures . . . . . . . . . . . . .108 11.1. Conceptual Data Structures. . . . . . . . . . . . . 105
11.2 Processing Mobility Headers . . . . . . . . . . . .109 11.2. Processing Mobility Headers . . . . . . . . . . . . 107
11.3 Packet Processing . . . . . . . . . . . . . . . . .110 11.3. Packet Processing . . . . . . . . . . . . . . . . . 107
11.3.1 Sending Packets While Away from Home . . . . 110 11.3.1. Sending Packets While Away from Home. . . . 107
11.3.2 Interaction with Outbound IPsec Processing . 113 11.3.2. Interaction with Outbound IPsec Processing. 110
11.3.3 Receiving Packets While Away from Home . . . 115 11.3.3. Receiving Packets While Away from Home. . . 112
11.3.4 Routing Multicast Packets . . . . . . . . . 116 11.3.4. Routing Multicast Packets . . . . . . . . . 114
11.3.5 Receiving ICMP Error Messages . . . . . . . 118 11.3.5. Receiving ICMP Error Messages . . . . . . . 115
11.3.6 Receiving Binding Error Messages . . . . . . 118 11.3.6. Receiving Binding Error Messages. . . . . . 116
11.4 Home Agent and Prefix Management . . . . . . . . . .119 11.4. Home Agent and Prefix Management. . . . . . . . . . 117
11.4.1 Dynamic Home Agent Address Discovery . . . . 119 11.4.1. Dynamic Home Agent Address Discovery. . . . 117
11.4.2 Sending Mobile Prefix Solicitations . . . . 120 11.4.2. Sending Mobile Prefix Solicitations . . . . 118
11.4.3 Receiving Mobile Prefix Advertisements . . . 121 11.4.3. Receiving Mobile Prefix Advertisements. . . 118
11.5 Movement . . . . . . . . . . . . . . . . . . . . . .122 11.5. Movement. . . . . . . . . . . . . . . . . . . . . . 120
11.5.1 Movement Detection . . . . . . . . . . . . . 122 11.5.1. Movement Detection. . . . . . . . . . . . . 120
11.5.2 Forming New Care-of Addresses . . . . . . . 124 11.5.2. Forming New Care-of Addresses . . . . . . . 122
11.5.3 Using Multiple Care-of Addresses . . . . . . 125 11.5.3. Using Multiple Care-of Addresses. . . . . . 123
11.5.4 Returning Home . . . . . . . . . . . . . . . 126 11.5.4. Returning Home. . . . . . . . . . . . . . . 124
11.6 Return Routability Procedure . . . . . . . . . . . .128 11.6. Return Routability Procedure. . . . . . . . . . . . 126
11.6.1 Sending Test Init Messages . . . . . . . . . 128 11.6.1. Sending Test Init Messages. . . . . . . . . 126
11.6.2 Receiving Test Messages . . . . . . . . . . 129 11.6.2. Receiving Test Messages . . . . . . . . . . 127
11.6.3 Protecting Return Routability Packets . . . 130 11.6.3. Protecting Return Routability Packets . . . 128
11.7 Processing Bindings . . . . . . . . . . . . . . . .130 11.7. Processing Bindings . . . . . . . . . . . . . . . . 128
11.7.1 Sending Binding Updates to the Home Agent . 131 11.7.1. Sending Binding Updates to the Home Agent . 128
11.7.2 Correspondent Registration . . . . . . . . . 133 11.7.2. Correspondent Registration. . . . . . . . . 131
11.7.3 Receiving Binding Acknowledgements . . . . . 136 11.7.3. Receiving Binding Acknowledgements. . . . . 134
11.7.4 Receiving Binding Refresh Requests . . . . . 138 11.7.4. Receiving Binding Refresh Requests. . . . . 136
11.8 Retransmissions and Rate Limiting . . . . . . . . .139 11.8. Retransmissions and Rate Limiting . . . . . . . . . 137
12. Protocol Constants . . . . . . . . . . . . . . . . . . . . 141 12. Protocol Constants . . . . . . . . . . . . . . . . . . . . 138
13. Protocol Configuration Variables . . . . . . . . . . . . . 142 13. Protocol Configuration Variables . . . . . . . . . . . . . 138
14. IANA Considerations . . . . . . . . . . . . . . . . . . . 143 14. IANA Considerations. . . . . . . . . . . . . . . . . . . . 139
15. Security Considerations . . . . . . . . . . . . . . . . . 145 15. Security Considerations. . . . . . . . . . . . . . . . . . 142
15.1 Threats . . . . . . . . . . . . . . . . . . . . . .145 15.1. Threats . . . . . . . . . . . . . . . . . . . . . . 142
15.2 Features . . . . . . . . . . . . . . . . . . . . . .147 15.2. Features. . . . . . . . . . . . . . . . . . . . . . 144
15.3 Binding Updates to Home Agent . . . . . . . . . . .148 15.3. Binding Updates to Home Agent . . . . . . . . . . . 145
15.4 Binding Updates to Correspondent Nodes . . . . . . .151 15.4. Binding Updates to Correspondent Nodes. . . . . . . 148
15.4.1 Overview . . . . . . . . . . . . . . . . . . 151 15.4.1. Overview. . . . . . . . . . . . . . . . . . 149
15.4.2 Achieved Security Properties . . . . . . . . 152 15.4.2. Achieved Security Properties. . . . . . . . 149
15.4.3 Comparison to Regular IPv6 Communications . 153 15.4.3. Comparison to Regular IPv6 Communications . 150
15.4.4 Replay Attacks . . . . . . . . . . . . . . . 155 15.4.4. Replay Attacks. . . . . . . . . . . . . . . 152
15.4.5 Denial-of-Service Attacks . . . . . . . . . 155 15.4.5. Denial-of-Service Attacks . . . . . . . . . 152
15.4.6 Key Lengths . . . . . . . . . . . . . . . . 156 15.4.6. Key Lengths . . . . . . . . . . . . . . . . 153
15.5 Dynamic Home Agent Address Discovery . . . . . . . .157 15.5. Dynamic Home Agent Address Discovery. . . . . . . . 154
15.6 Mobile Prefix Discovery . . . . . . . . . . . . . .157 15.6. Mobile Prefix Discovery . . . . . . . . . . . . . . 155
15.7 Tunneling via the Home Agent . . . . . . . . . . . .158 15.7. Tunneling via the Home Agent. . . . . . . . . . . . 155
15.8 Home Address Option . . . . . . . . . . . . . . . .158 15.8. Home Address Option . . . . . . . . . . . . . . . . 156
15.9 Type 2 Routing Header . . . . . . . . . . . . . . .159 15.9. Type 2 Routing Header . . . . . . . . . . . . . . . 156
16. Contributors . . . . . . . . . . . . . . . . . . . . . . . 161 16. Contributors . . . . . . . . . . . . . . . . . . . . . . . 157
17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 162 17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 157
Normative References . . . . . . . . . . . . . . . . . . . 163 18. References . . . . . . . . . . . . . . . . . . . . . . . . 158
Informative References . . . . . . . . . . . . . . . . . . 165 18.1. Normative References. . . . . . . . . . . . . . . . 158
Authors' Addresses . . . . . . . . . . . . . . . . . . . . 166 18.2. Informative References. . . . . . . . . . . . . . . 159
A. Changes from Previous Version of the Draft . . . . . . . . 167 Appendix A. Future Extensions . . . . . . . . . . . . . . . . . 161
B. Future Extensions . . . . . . . . . . . . . . . . . . . . 168 A.1. Piggybacking. . . . . . . . . . . . . . . . . . . . 161
B.1 Piggybacking . . . . . . . . . . . . . . . . . . . . . . . 168 A.2. Triangular Routing. . . . . . . . . . . . . . . . . 161
B.2 Triangular Routing . . . . . . . . . . . . . . . . . . . . 168 A.3. New Authorization Methods . . . . . . . . . . . . . 161
B.3 New Authorization Methods . . . . . . . . . . . . . . . . 168 A.4. Dynamically Generated Home Addresses. . . . . . . . 161
B.4 Dynamically Generated Home Addresses . . . . . . . . . . . 168 A.5. Remote Home Address Configuration . . . . . . . . . 162
B.5 Remote Home Address Configuration . . . . . . . . . . . . 168 A.6. Neighbor Discovery Extensions . . . . . . . . . . . 163
B.6 Neighbor Discovery Extensions . . . . . . . . . . . . . . 169 Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . . . 164
Intellectual Property and Copyright Statements . . . . . . 171 Full Copyright Statement. . . . . . . . . . . . . . . . . . . . . 165
1. Introduction 1. Introduction
This document specifies a protocol which allows nodes to remain This document specifies a protocol which allows nodes to remain
reachable while moving around in the IPv6 Internet. Without specific reachable while moving around in the IPv6 Internet. Without specific
support for mobility in IPv6 [11], packets destined to a mobile node support for mobility in IPv6 [11], packets destined to a mobile node
would not be able to reach it while the mobile node is away from its would not be able to reach it while the mobile node is away from its
home link. In order to continue communication in spite of its home link. In order to continue communication in spite of its
movement, a mobile node could change its IP address each time it movement, a mobile node could change its IP address each time it
moves to a new link, but the mobile node would then not be able to moves to a new link, but the mobile node would then not be able to
maintain transport and higher-layer connections when it changes maintain transport and higher-layer connections when it changes
location. Mobility support in IPv6 is particularly important, as location. Mobility support in IPv6 is particularly important, as
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thus transparent to transport and higher-layer protocols and thus transparent to transport and higher-layer protocols and
applications. applications.
The Mobile IPv6 protocol is just as suitable for mobility across The Mobile IPv6 protocol is just as suitable for mobility across
homogeneous media as for mobility across heterogeneous media. For homogeneous media as for mobility across heterogeneous media. For
example, Mobile IPv6 facilitates node movement from one Ethernet example, Mobile IPv6 facilitates node movement from one Ethernet
segment to another as well as it facilitates node movement from an segment to another as well as it facilitates node movement from an
Ethernet segment to a wireless LAN cell, with the mobile node's IP Ethernet segment to a wireless LAN cell, with the mobile node's IP
address remaining unchanged in spite of such movement. address remaining unchanged in spite of such movement.
One can think of the Mobile IPv6 protocol as solving the One can think of the Mobile IPv6 protocol as solving the network-
network-layer mobility management problem. Some mobility management layer mobility management problem. Some mobility management
applications -- for example, handover among wireless transceivers, applications -- for example, handover among wireless transceivers,
each of which covers only a very small geographic area -- have been each of which covers only a very small geographic area -- have been
solved using link-layer techniques. For example, in many current solved using link-layer techniques. For example, in many current
wireless LAN products, link-layer mobility mechanisms allow a wireless LAN products, link-layer mobility mechanisms allow a
"handover" of a mobile node from one cell to another, re-establishing "handover" of a mobile node from one cell to another, re-establishing
link-layer connectivity to the node in each new location. link-layer connectivity to the node in each new location.
Mobile IPv6 does not attempt to solve all general problems related to Mobile IPv6 does not attempt to solve all general problems related to
the use of mobile computers or wireless networks. In particular, the use of mobile computers or wireless networks. In particular,
this protocol does not attempt to solve: this protocol does not attempt to solve:
o Handling links with unidirectional connectivity or partial o Handling links with unidirectional connectivity or partial
reachability, such as the hidden terminal problem where a host is reachability, such as the hidden terminal problem where a host is
hidden from only some of the routers on the link. hidden from only some of the routers on the link.
o Access control on a link being visited by a mobile node. o Access control on a link being visited by a mobile node.
o Local or hierarchical forms of mobility management (similar to o Local or hierarchical forms of mobility management (similar to
many current link-layer mobility management solutions). many current link-layer mobility management solutions).
o Assistance for adaptive applications o Assistance for adaptive applications.
o Mobile routers o Mobile routers.
o Service Discovery o Service Discovery.
o Distinguishing between packets lost due to bit errors vs. network o Distinguishing between packets lost due to bit errors vs. network
congestion congestion.
2. Comparison with Mobile IP for IPv4 2. Comparison with Mobile IP for IPv4
The design of Mobile IP support in IPv6 (Mobile IPv6) benefits both The design of Mobile IP support in IPv6 (Mobile IPv6) benefits both
from the experiences gained from the development of Mobile IP support from the experiences gained from the development of Mobile IP support
in IPv4 (Mobile IPv4) [22, 23, 24], and from the opportunities in IPv4 (Mobile IPv4) [22, 23, 24], and from the opportunities
provided by IPv6. Mobile IPv6 thus shares many features with Mobile provided by IPv6. Mobile IPv6 thus shares many features with Mobile
IPv4, but is integrated into IPv6 and offers many other improvements. IPv4, but is integrated into IPv6 and offers many other improvements.
This section summarizes the major differences between Mobile IPv4 and This section summarizes the major differences between Mobile IPv4 and
Mobile IPv6: Mobile IPv6:
o There is no need to deploy special routers as "foreign agents", as o There is no need to deploy special routers as "foreign agents", as
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improves the robustness of the protocol. improves the robustness of the protocol.
o The use of IPv6 encapsulation (and the routing header) removes the o The use of IPv6 encapsulation (and the routing header) removes the
need in Mobile IPv6 to manage "tunnel soft state". need in Mobile IPv6 to manage "tunnel soft state".
o The dynamic home agent address discovery mechanism in Mobile IPv6 o The dynamic home agent address discovery mechanism in Mobile IPv6
returns a single reply to the mobile node. The directed broadcast returns a single reply to the mobile node. The directed broadcast
approach used in IPv4 returns separate replies from each home approach used in IPv4 returns separate replies from each home
agent. agent.
3. Terminology 3. Terminology
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [2]. document are to be interpreted as described in BCP 14, RFC 2119 [2].
3.1 General Terms 3.1. General Terms
IP IP
Internet Protocol Version 6 (IPv6). Internet Protocol Version 6 (IPv6).
node node
A device that implements IP. A device that implements IP.
router router
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routing header routing header
A routing header may be present as an IPv6 header extension, and A routing header may be present as an IPv6 header extension, and
indicates that the payload has to be delivered to a destination indicates that the payload has to be delivered to a destination
IPv6 address in some way that is different from what would be IPv6 address in some way that is different from what would be
carried out by standard Internet routing. In this document, use carried out by standard Internet routing. In this document, use
of the term "routing header" typically refers to use of a type 2 of the term "routing header" typically refers to use of a type 2
routing header, as specified in Section 6.4. routing header, as specified in Section 6.4.
'|' (concatenation) "|" (concatenation)
Some formulas in this specification use the symbol '|' indicate Some formulas in this specification use the symbol "|" to indicate
bytewise concatenation, as in A | B. This concatenation requires bytewise concatenation, as in A | B. This concatenation requires
that all of the octets of the datum A appear first in the result, that all of the octets of the datum A appear first in the result,
followed by all of the octets of the datum B. followed by all of the octets of the datum B.
First (size, input) First (size, input)
Some formulas in this specification use a functional form "First Some formulas in this specification use a functional form "First
(size, input)" to indicate truncation of the "input" data so that (size, input)" to indicate truncation of the "input" data so that
only the first "size" bits remain to be used. only the first "size" bits remain to be used.
3.2 Mobile IPv6 Terms 3.2. Mobile IPv6 Terms
home address home address
A unicast routable address assigned to a mobile node, used as the A unicast routable address assigned to a mobile node, used as the
permanent address of the mobile node. This address is within the permanent address of the mobile node. This address is within the
mobile node's home link. Standard IP routing mechanisms will mobile node's home link. Standard IP routing mechanisms will
deliver packets destined for a mobile node's home address to its deliver packets destined for a mobile node's home address to its
home link. Mobile nodes can have multiple home addresses, for home link. Mobile nodes can have multiple home addresses, for
instance when there are multiple home prefixes on the home link. instance when there are multiple home prefixes on the home link.
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A router on a mobile node's home link with which the mobile node A router on a mobile node's home link with which the mobile node
has registered its current care-of address. While the mobile node has registered its current care-of address. While the mobile node
is away from home, the home agent intercepts packets on the home is away from home, the home agent intercepts packets on the home
link destined to the mobile node's home address, encapsulates link destined to the mobile node's home address, encapsulates
them, and tunnels them to the mobile node's registered care-of them, and tunnels them to the mobile node's registered care-of
address. address.
binding binding
The association of the home address of a mobile node with a The association of the home address of a mobile node with a care-
care-of address for that mobile node, along with the remaining of address for that mobile node, along with the remaining lifetime
lifetime of that association. of that association.
registration registration
The process during which a mobile node sends a Binding Update to The process during which a mobile node sends a Binding Update to
its home agent or a correspondent node, causing a binding for the its home agent or a correspondent node, causing a binding for the
mobile node to be registered. mobile node to be registered.
mobility message mobility message
A message containing a Mobility Header (see Section 6.1). A message containing a Mobility Header (see Section 6.1).
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node, and are kept secret within the correspondent node. node, and are kept secret within the correspondent node.
nonce index nonce index
A nonce index is used to indicate which nonces have been used when A nonce index is used to indicate which nonces have been used when
creating keygen token values, without revealing the nonces creating keygen token values, without revealing the nonces
themselves. themselves.
cookie cookie
A cookie is a random number used by a mobile nodes to prevent A cookie is a random number used by a mobile node to prevent
spoofing by a bogus correspondent node in the return routability spoofing by a bogus correspondent node in the return routability
procedure. procedure.
care-of init cookie care-of init cookie
A cookie sent to the correspondent node in the Care-of Test Init A cookie sent to the correspondent node in the Care-of Test Init
message, to be returned in the Care-of Test message. message, to be returned in the Care-of Test message.
home init cookie home init cookie
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A keygen token sent by the correspondent node in the Home Test A keygen token sent by the correspondent node in the Home Test
message. message.
binding management key (Kbm) binding management key (Kbm)
A binding management key (Kbm) is a key used for authorizing a A binding management key (Kbm) is a key used for authorizing a
binding cache management message (e.g., Binding Update or Binding binding cache management message (e.g., Binding Update or Binding
Acknowledgement). Return routability provides a way to create a Acknowledgement). Return routability provides a way to create a
binding management key. binding management key.
4. Overview of Mobile IPv6 4. Overview of Mobile IPv6
4.1 Basic Operation 4.1. Basic Operation
A mobile node is always expected to be addressable at its home A mobile node is always expected to be addressable at its home
address, whether it is currently attached to its home link or is away address, whether it is currently attached to its home link or is away
from home. The "home address" is an IP address assigned to the from home. The "home address" is an IP address assigned to the
mobile node within its home subnet prefix on its home link. While a mobile node within its home subnet prefix on its home link. While a
mobile node is at home, packets addressed to its home address are mobile node is at home, packets addressed to its home address are
routed to the mobile node's home link, using conventional Internet routed to the mobile node's home link, using conventional Internet
routing mechanisms. routing mechanisms.
While a mobile node is attached to some foreign link away from home, While a mobile node is attached to some foreign link away from home,
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limited support for the reconfiguration of the home network. In limited support for the reconfiguration of the home network. In
these cases, the mobile node may not know the IP address of its own these cases, the mobile node may not know the IP address of its own
home agent, and even the home subnet prefixes may change over time. home agent, and even the home subnet prefixes may change over time.
A mechanism, known as "dynamic home agent address discovery" allows a A mechanism, known as "dynamic home agent address discovery" allows a
mobile node to dynamically discover the IP address of a home agent on mobile node to dynamically discover the IP address of a home agent on
its home link, even when the mobile node is away from home. Mobile its home link, even when the mobile node is away from home. Mobile
nodes can also learn new information about home subnet prefixes nodes can also learn new information about home subnet prefixes
through the "mobile prefix discovery" mechanism. These mechanisms through the "mobile prefix discovery" mechanism. These mechanisms
are described starting from Section 6.5. are described starting from Section 6.5.
4.2 New IPv6 Protocol 4.2. New IPv6 Protocol
Mobile IPv6 defines a new IPv6 protocol, using the Mobility Header Mobile IPv6 defines a new IPv6 protocol, using the Mobility Header
(see Section 6.1). This Header is used to carry the following (see Section 6.1). This Header is used to carry the following
messages: messages:
Home Test Init Home Test Init
Home Test Home Test
Care-of Test Init Care-of Test Init
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close to expiration. The correspondent node may use, for close to expiration. The correspondent node may use, for
instance, recent traffic and open transport layer connections as instance, recent traffic and open transport layer connections as
an indication of active use. an indication of active use.
Binding Error Binding Error
The Binding Error is used by the correspondent node to signal an The Binding Error is used by the correspondent node to signal an
error related to mobility, such as an inappropriate attempt to use error related to mobility, such as an inappropriate attempt to use
the Home Address destination option without an existing binding. the Home Address destination option without an existing binding.
4.3 New IPv6 Destination Option 4.3. New IPv6 Destination Option
Mobile IPv6 defines a new IPv6 destination option, the Home Address Mobile IPv6 defines a new IPv6 destination option, the Home Address
destination option. This option is described in detail in Section destination option. This option is described in detail in Section
6.3. 6.3.
4.4 New IPv6 ICMP Messages 4.4. New IPv6 ICMP Messages
Mobile IPv6 also introduces four new ICMP message types, two for use Mobile IPv6 also introduces four new ICMP message types, two for use
in the dynamic home agent address discovery mechanism, and two for in the dynamic home agent address discovery mechanism, and two for
renumbering and mobile configuration mechanisms. As described in renumbering and mobile configuration mechanisms. As described in
Section 10.5 and Section 11.4.1, the following two new ICMP message Section 10.5 and Section 11.4.1, the following two new ICMP message
types are used for home agent address discovery: types are used for home agent address discovery:
o Home Agent Address Discovery Request, described in Section 6.5. o Home Agent Address Discovery Request, described in Section 6.5.
o Home Agent Address Discovery Reply, described in Section 6.6. o Home Agent Address Discovery Reply, described in Section 6.6.
The next two message types are used for network renumbering and The next two message types are used for network renumbering and
address configuration on the mobile node, as described in Section address configuration on the mobile node, as described in Section
10.6: 10.6:
o Mobile Prefix Solicitation, described in Section 6.7. o Mobile Prefix Solicitation, described in Section 6.7.
o Mobile Prefix Advertisement, described in Section 6.8. o Mobile Prefix Advertisement, described in Section 6.8.
4.5 Conceptual Data Structure Terminology 4.5. Conceptual Data Structure Terminology
This document describes the Mobile IPv6 protocol in terms of the This document describes the Mobile IPv6 protocol in terms of the
following conceptual data structures: following conceptual data structures:
Binding Cache Binding Cache
A cache of bindings for other nodes. This cache is maintained by A cache of bindings for other nodes. This cache is maintained by
home agents and correspondent nodes. The cache contains both home agents and correspondent nodes. The cache contains both
"correspondent registration" entries (see Section 9.1) and "home "correspondent registration" entries (see Section 9.1) and "home
registration" entries (see Section 10.1). registration" entries (see Section 10.1).
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11.1. 11.1.
Home Agents List Home Agents List
Home agents need to know which other home agents are on the same Home agents need to know which other home agents are on the same
link. This information is stored in the Home Agents List, as link. This information is stored in the Home Agents List, as
described in more detail in Section 10.1. The list is used for described in more detail in Section 10.1. The list is used for
informing mobile nodes during dynamic home agent address informing mobile nodes during dynamic home agent address
discovery. discovery.
4.6 Site-Local Addressability 4.6. Site-Local Addressability
This specification requires that home and care-of addresses MUST be This specification requires that home and care-of addresses MUST be
unicast routable addresses. Site-local addresses may be usable on unicast routable addresses. Site-local addresses may be usable on
networks that are not connected to the Internet, but this networks that are not connected to the Internet, but this
specification does not define when such usage is safe and when not. specification does not define when such usage is safe and when it is
Mobile nodes may not be aware of which site they are currently in, it not. Mobile nodes may not be aware of which site they are currently
is hard to prevent accidental attachment to other sites, and in, it is hard to prevent accidental attachment to other sites, and
ambiguity of site-local addresses can cause problems if the home and ambiguity of site-local addresses can cause problems if the home and
visited networks use the same addresses. Therefore, site-local visited networks use the same addresses. Therefore, site-local
addresses SHOULD NOT be used as home or care-of addresses. addresses SHOULD NOT be used as home or care-of addresses.
5. Overview of Mobile IPv6 Security 5. Overview of Mobile IPv6 Security
This specification provides a number of security features. These This specification provides a number of security features. These
include the protection of Binding Updates both to home agents and include the protection of Binding Updates both to home agents and
correspondent nodes, the protection of mobile prefix discovery, and correspondent nodes, the protection of mobile prefix discovery, and
the protection of the mechanisms that Mobile IPv6 uses for the protection of the mechanisms that Mobile IPv6 uses for
transporting data packets. transporting data packets.
Binding Updates are protected by the use of IPsec extension headers, Binding Updates are protected by the use of IPsec extension headers,
or by the use of the Binding Authorization Data option. This option or by the use of the Binding Authorization Data option. This option
employs a binding management key, Kbm, which can be established employs a binding management key, Kbm, which can be established
through the return routability procedure. Mobile prefix discovery is through the return routability procedure. Mobile prefix discovery is
protected through the use of IPsec extension headers. Mechanisms protected through the use of IPsec extension headers. Mechanisms
related to transporting payload packets - such as the Home Address related to transporting payload packets - such as the Home Address
destination option and type 2 routing header - have been specified in destination option and type 2 routing header - have been specified in
a manner which restricts their use in attacks. a manner which restricts their use in attacks.
5.1 Binding Updates to Home Agents 5.1. Binding Updates to Home Agents
The mobile node and the home agent MUST use an IPsec security The mobile node and the home agent MUST use an IPsec security
association to protect the integrity and authenticity of the Binding association to protect the integrity and authenticity of the Binding
Updates and Acknowledgements. Both the mobile nodes and the home Updates and Acknowledgements. Both the mobile nodes and the home
agents MUST support and SHOULD use the Encapsulating Security Payload agents MUST support and SHOULD use the Encapsulating Security Payload
(ESP) [6] header in transport mode and MUST use a non-NULL payload (ESP) [6] header in transport mode and MUST use a non-NULL payload
authentication algorithm to provide data origin authentication, authentication algorithm to provide data origin authentication,
connectionless integrity and optional anti-replay protection. Note connectionless integrity and optional anti-replay protection. Note
that Authentication Header (AH) [5] is also possible but for brevity that Authentication Header (AH) [5] is also possible but for brevity
not discussed in this specification. not discussed in this specification.
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Acknowledgements. The home address is used in these packets as a Acknowledgements. The home address is used in these packets as a
source or destination, or in the Home Address Destination option or source or destination, or in the Home Address Destination option or
the type 2 routing header. the type 2 routing header.
As with all IPsec security associations in this specification, manual As with all IPsec security associations in this specification, manual
configuration of security associations MUST be supported. The used configuration of security associations MUST be supported. The used
shared secrets MUST be random and unique for different mobile nodes, shared secrets MUST be random and unique for different mobile nodes,
and MUST be distributed off-line to the mobile nodes. and MUST be distributed off-line to the mobile nodes.
Automatic key management with IKE [9] MAY be supported. When IKE is Automatic key management with IKE [9] MAY be supported. When IKE is
used, either the security policy database entries or the MIPv6 used, either the security policy database entries or the Mobile IPv6
processing MUST unequivocally identify the IKE phase 1 credentials processing MUST unequivocally identify the IKE phase 1 credentials
which can be used to authorize the creation of security associations which can be used to authorize the creation of security associations
for protecting Binding Updates for a particular home address. How for protecting Binding Updates for a particular home address. How
these mappings are maintained is outside the scope of this these mappings are maintained is outside the scope of this
specification, but they may be maintained, for instance, as a locally specification, but they may be maintained, for instance, as a locally
administered table in the home agent. If the phase 1 identity is a administered table in the home agent. If the phase 1 identity is a
Fully Qualified Domain Name (FQDN), secure forms of DNS may also be Fully Qualified Domain Name (FQDN), secure forms of DNS may also be
used. used.
Section 11.3.2 discusses how IKE connections to the home agent need a Section 11.3.2 discusses how IKE connections to the home agent need a
careful treatment of the addresses used for transporting IKE. This careful treatment of the addresses used for transporting IKE. This
is necessary to ensure that a Binding Update is not needed before the is necessary to ensure that a Binding Update is not needed before the
IKE exchange which is needed for securing the Binding Update. IKE exchange which is needed for securing the Binding Update.
When IKE version 1 is used with preshared secret authentication When IKE version 1 is used with preshared secret authentication
between the mobile node and the home agent, aggressive mode MUST be between the mobile node and the home agent, aggressive mode MUST be
used. Similarly, the ID_IPV6_ADDR Identity Payload MUST NOT be used used.
in IKEv1 phase 1.
The ID_IPV6_ADDR Identity Payload MUST NOT be used in IKEv1 phase 1.
Reference [21] contains a more detailed description and examples on Reference [21] contains a more detailed description and examples on
using IPsec to protect the communications between the mobile node and using IPsec to protect the communications between the mobile node and
the home agent. the home agent.
5.2 Binding Updates to Correspondent Nodes 5.2. Binding Updates to Correspondent Nodes
The protection of Binding Updates sent to correspondent nodes does The protection of Binding Updates sent to correspondent nodes does
not require the configuration of security associations or the not require the configuration of security associations or the
existence of an authentication infrastructure between the mobile existence of an authentication infrastructure between the mobile
nodes and correspondent nodes. Instead, a method called the return nodes and correspondent nodes. Instead, a method called the return
routability procedure is used to assure that the right mobile node is routability procedure is used to assure that the right mobile node is
sending the message. This method does not protect against attackers sending the message. This method does not protect against attackers
who are on the path between the home network and the correspondent who are on the path between the home network and the correspondent
node. However, attackers in such a location are capable of node. However, attackers in such a location are capable of
performing the same attacks even without Mobile IPv6. The main performing the same attacks even without Mobile IPv6. The main
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The integrity and authenticity of the Binding Updates messages to The integrity and authenticity of the Binding Updates messages to
correspondent nodes is protected by using a keyed-hash algorithm. correspondent nodes is protected by using a keyed-hash algorithm.
The binding management key, Kbm, is used to key the hash algorithm The binding management key, Kbm, is used to key the hash algorithm
for this purpose. Kbm is established using data exchanged during the for this purpose. Kbm is established using data exchanged during the
return routability procedure. The data exchange is accomplished by return routability procedure. The data exchange is accomplished by
use of node keys, nonces, cookies, tokens, and certain cryptographic use of node keys, nonces, cookies, tokens, and certain cryptographic
functions. Section 5.2.5 outlines the basic return routability functions. Section 5.2.5 outlines the basic return routability
procedure. Section 5.2.6 shows how the results of this procedure are procedure. Section 5.2.6 shows how the results of this procedure are
used to authorize a Binding Update to a correspondent node. used to authorize a Binding Update to a correspondent node.
5.2.1 Node Keys 5.2.1. Node Keys
Each correspondent node has a secret key, Kcn, called the "node key", Each correspondent node has a secret key, Kcn, called the "node key",
which it uses to produce the keygen tokens sent to the mobile nodes. which it uses to produce the keygen tokens sent to the mobile nodes.
The node key MUST be a random number, 20 octets in length. The node The node key MUST be a random number, 20 octets in length. The node
key allows the correspondent node to verify that the keygen tokens key allows the correspondent node to verify that the keygen tokens
used by the mobile node in authorizing a Binding Update are indeed used by the mobile node in authorizing a Binding Update are indeed
its own. This key MUST NOT be shared with any other entity. its own. This key MUST NOT be shared with any other entity.
A correspondent node MAY generate a fresh node key at any time; this A correspondent node MAY generate a fresh node key at any time; this
avoids the need for secure persistent key storage. Procedures for avoids the need for secure persistent key storage. Procedures for
optionally updating the node key are discussed later in Section optionally updating the node key are discussed later in Section
5.2.7. 5.2.7.
5.2.2 Nonces 5.2.2. Nonces
Each correspondent node also generates nonces at regular intervals. Each correspondent node also generates nonces at regular intervals.
The nonces should be generated by using a random number generator The nonces should be generated by using a random number generator
that is known to have good randomness properties [1]. A that is known to have good randomness properties [1]. A
correspondent node may use the same Kcn and nonce with all the correspondent node may use the same Kcn and nonce with all the
mobiles it is in communication with. mobiles it is in communication with.
Each nonce is identified by a nonce index. When a new nonce is Each nonce is identified by a nonce index. When a new nonce is
generated, it must be associated with a new nonce index; this may be generated, it must be associated with a new nonce index; this may be
done, for example, by incrementing the value of the previous nonce done, for example, by incrementing the value of the previous nonce
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will be rejected. will be rejected.
The specific nonce index values cannot be used by mobile nodes to The specific nonce index values cannot be used by mobile nodes to
determine the validity of the nonce. Expected validity times for the determine the validity of the nonce. Expected validity times for the
nonces values and the procedures for updating them are discussed nonces values and the procedures for updating them are discussed
later in Section 5.2.7. later in Section 5.2.7.
A nonce is an octet string of any length. The recommended length is A nonce is an octet string of any length. The recommended length is
64 bits. 64 bits.
5.2.3 Cookies and Tokens 5.2.3. Cookies and Tokens
The return routability address test procedure uses cookies and keygen The return routability address test procedure uses cookies and keygen
tokens as opaque values within the test init and test messages, tokens as opaque values within the test init and test messages,
respectively. respectively.
o The "home init cookie" and "care-of init cookie" are 64 bit values o The "home init cookie" and "care-of init cookie" are 64 bit values
sent to the correspondent node from the mobile node, and later sent to the correspondent node from the mobile node, and later
returned to the mobile node. The home init cookie is sent in the returned to the mobile node. The home init cookie is sent in the
Home Test Init message, and returned in the Home Test message. Home Test Init message, and returned in the Home Test message.
The care-of init cookie is sent in the Care-of Test Init message, The care-of init cookie is sent in the Care-of Test Init message,
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or Care-of Test message matches the Home Test Init or Care-of Test or Care-of Test message matches the Home Test Init or Care-of Test
Init message, respectively. These cookies also serve to ensure that Init message, respectively. These cookies also serve to ensure that
parties who have not seen the request cannot spoof responses. parties who have not seen the request cannot spoof responses.
Home and care-of keygen tokens are produced by the correspondent node Home and care-of keygen tokens are produced by the correspondent node
based on its currently active secret key (Kcn) and nonces, as well as based on its currently active secret key (Kcn) and nonces, as well as
the home or care-of address (respectively). A keygen token is valid the home or care-of address (respectively). A keygen token is valid
as long as both the secret key (Kcn) and the nonce used to create it as long as both the secret key (Kcn) and the nonce used to create it
are valid. are valid.
5.2.4 Cryptographic Functions 5.2.4. Cryptographic Functions
In this specification, the function used to compute hash values is In this specification, the function used to compute hash values is
SHA1 [20]. Message Authentication Codes (MACs) are computed using SHA1 [20]. Message Authentication Codes (MACs) are computed using
HMAC_SHA1 [25, 20]. HMAC_SHA1(K,m) denotes such a MAC computed on HMAC_SHA1 [25, 20]. HMAC_SHA1(K,m) denotes such a MAC computed on
message m with key K. message m with key K.
5.2.5 Return Routability Procedure 5.2.5. Return Routability Procedure
The Return Routability Procedure enables the correspondent node to The Return Routability Procedure enables the correspondent node to
obtain some reasonable assurance that the mobile node is in fact obtain some reasonable assurance that the mobile node is in fact
addressable at its claimed care-of address as well as at its home addressable at its claimed care-of address as well as at its home
address. Only with this assurance is the correspondent node able to address. Only with this assurance is the correspondent node able to
accept Binding Updates from the mobile node which would then instruct accept Binding Updates from the mobile node which would then instruct
the correspondent node to direct that mobile node's data traffic to the correspondent node to direct that mobile node's data traffic to
its claimed care-of address. its claimed care-of address.
This is done by testing whether packets addressed to the two claimed This is done by testing whether packets addressed to the two claimed
addresses are routed to the mobile node. The mobile node can pass addresses are routed to the mobile node. The mobile node can pass
the test only if it is able to supply proof that it received certain the test only if it is able to supply proof that it received certain
data (the "keygen tokens") which the correspondent node sends to data (the "keygen tokens") which the correspondent node sends to
those addresses. These data are combined by the mobile node into a those addresses. These data are combined by the mobile node into a
binding management key, denoted Kbm. binding management key, denoted Kbm.
The below figure shows the message flow for the return routability The figure below shows the message flow for the return routability
procedure. procedure.
Mobile node Home agent Correspondent node Mobile node Home agent Correspondent node
| | | |
| Home Test Init (HoTI) | | | Home Test Init (HoTI) | |
|------------------------->|------------------------->| |------------------------->|------------------------->|
| | | | | |
| Care-of Test Init (CoTI) | | Care-of Test Init (CoTI) |
|---------------------------------------------------->| |---------------------------------------------------->|
| | | |
| | Home Test (HoT) | | | Home Test (HoT) |
|<-------------------------|<-------------------------| |<-------------------------|<-------------------------|
| | | | | |
| Care-of Test (CoT) | | Care-of Test (CoT) |
|<----------------------------------------------------| |<----------------------------------------------------|
| | | |
The Home and Care-of Test Init messages are sent at the same time. The Home and Care-of Test Init messages are sent at the same time.
The procedure requires very little processing at the correspondent The procedure requires very little processing at the correspondent
node, and the Home and Care-of Test messages can be returned quickly, node, and the Home and Care-of Test messages can be returned quickly,
perhaps nearly simultaneously. These four messages form the return perhaps nearly simultaneously. These four messages form the return
routability procedure. routability procedure.
Home Test Init Home Test Init
A mobile node sends a Home Test Init message to the correspondent A mobile node sends a Home Test Init message to the correspondent
skipping to change at page 25, line 4 skipping to change at page 23, line 33
perhaps nearly simultaneously. These four messages form the return perhaps nearly simultaneously. These four messages form the return
routability procedure. routability procedure.
Home Test Init Home Test Init
A mobile node sends a Home Test Init message to the correspondent A mobile node sends a Home Test Init message to the correspondent
node (via the home agent) to acquire the home keygen token. The node (via the home agent) to acquire the home keygen token. The
contents of the message can be summarized as follows: contents of the message can be summarized as follows:
* Source Address = home address * Source Address = home address
* Destination Address = correspondent * Destination Address = correspondent
* Parameters: * Parameters:
+ home init cookie + home init cookie
The Home Test Init message conveys the mobile node's home address The Home Test Init message conveys the mobile node's home address
to the correspondent node. The mobile node also sends along a to the correspondent node. The mobile node also sends along a
home init cookie that the correspondent node must return later. home init cookie that the correspondent node must return later.
The Home Test Init message is reverse tunneled through the home The Home Test Init message is reverse tunneled through the home
agent. (The headers and addresses related to reverse tunneling agent. (The headers and addresses related to reverse tunneling
have been omitted from the above discussion of the message have been omitted from the above discussion of the message
contents.) The mobile node remembers these cookie values to obtain contents.) The mobile node remembers these cookie values to
some assurance that its protocol messages are being processed by obtain some assurance that its protocol messages are being
the desired correspondent node. processed by the desired correspondent node.
Care-of Test Init Care-of Test Init
The mobile node sends a Care-of Test Init message to the The mobile node sends a Care-of Test Init message to the
correspondent node (directly, not via the home agent) to acquire correspondent node (directly, not via the home agent) to acquire
the care-of keygen token. The contents of this message can be the care-of keygen token. The contents of this message can be
summarized as follows: summarized as follows:
* Source Address = care-of address * Source Address = care-of address
* Destination Address = correspondent * Destination Address = correspondent
* Parameters: * Parameters:
+ care-of init cookie + care-of init cookie
The Care-of Test Init message conveys the mobile node's care-of The Care-of Test Init message conveys the mobile node's care-of
address to the correspondent node. The mobile node also sends address to the correspondent node. The mobile node also sends
along a care-of init cookie that the correspondent node must along a care-of init cookie that the correspondent node must
return later. The Care-of Test Init message is sent directly to return later. The Care-of Test Init message is sent directly to
the correspondent node. the correspondent node.
Home Test Home Test
The Home Test message is sent in response to a Home Test Init The Home Test message is sent in response to a Home Test Init
skipping to change at page 26, line 17 skipping to change at page 25, line 8
+ home init cookie + home init cookie
+ home keygen token + home keygen token
+ home nonce index + home nonce index
When the correspondent node receives the Home Test Init message, When the correspondent node receives the Home Test Init message,
it generates a home keygen token as follows: it generates a home keygen token as follows:
home keygen token := home keygen token :=
First (64, HMAC_SHA1 (Kcn, (home address | nonce | 0))) First (64, HMAC_SHA1 (Kcn, (home address | nonce | 0)))
where | denotes concatenation. The final "0" inside the HMAC_SHA1 where | denotes concatenation. The final "0" inside the HMAC_SHA1
function is a single zero octet, used to distinguish home and function is a single zero octet, used to distinguish home and
care-of cookies from each other. care-of cookies from each other.
The home keygen token is formed from the first 64 bits of the MAC. The home keygen token is formed from the first 64 bits of the MAC.
The home keygen token tests that the mobile node can receive The home keygen token tests that the mobile node can receive were
messages sent to its home address. Kcn is used in the production messages sent to its home address. Kcn is used in the production
of home keygen token in order to allow the correspondent node to of home keygen token in order to allow the correspondent node to
verify that it generated the home and care-of nonces, without verify that it generated the home and care-of nonces, without
forcing the correspondent node to remember a list of all tokens it forcing the correspondent node to remember a list of all tokens it
has handed out. has handed out.
The Home Test message is sent to the mobile node via the home The Home Test message is sent to the mobile node via the home
network, where it is presumed that the home agent will tunnel the network, where it is presumed that the home agent will tunnel the
message to the mobile node. This means that the mobile node needs message to the mobile node. This means that the mobile node needs
to already have sent a Binding Update to the home agent, so that to already have sent a Binding Update to the home agent, so that
skipping to change at page 27, line 28 skipping to change at page 26, line 15
+ care-of init cookie + care-of init cookie
+ care-of keygen token + care-of keygen token
+ care-of nonce index + care-of nonce index
When the correspondent node receives the Care-of Test Init When the correspondent node receives the Care-of Test Init
message, it generates a care-of keygen token as follows: message, it generates a care-of keygen token as follows:
care-of keygen token := care-of keygen token :=
First (64, HMAC_SHA1 (Kcn, (care-of address | nonce | 1))) First (64, HMAC_SHA1 (Kcn, (care-of address | nonce | 1)))
Here, the final "1" inside the HMAC_SHA1 function is a single Here, the final "1" inside the HMAC_SHA1 function is a single
octet containing the hex value 0x01, and is used to distinguish octet containing the hex value 0x01, and is used to distinguish
home and care-of cookies from each other. The keygen token is home and care-of cookies from each other. The keygen token is
formed from the first 64 bits of the MAC, and sent directly to the formed from the first 64 bits of the MAC, and sent directly to the
mobile node at its care-of address. The care-of init cookie from mobile node at its care-of address. The care-of init cookie from
the Care-of Test Init message is returned to ensure that the the Care-of Test Init message is returned to ensure that the
message comes from a node on the route to the correspondent node. message comes from a node on the route to the correspondent node.
The care-of nonce index is provided to identify the nonce used for The care-of nonce index is provided to identify the nonce used for
the care-of keygen token. The home and care-of nonce indices MAY the care-of keygen token. The home and care-of nonce indices MAY
be the same, or different, in the Home and Care-of Test messages. be the same, or different, in the Home and Care-of Test messages.
When the mobile node has received both the Home and Care-of Test When the mobile node has received both the Home and Care-of Test
messages, the return routability procedure is complete. As a result messages, the return routability procedure is complete. As a result
of the procedure, the mobile node has the data it needs to send a of the procedure, the mobile node has the data it needs to send a
Binding Update to the correspondent node. The mobile node hashes the Binding Update to the correspondent node. The mobile node hashes the
tokens together to form a 20 octet binding key Kbm: tokens together to form a 20 octet binding key Kbm:
Kbm = SHA1 (home keygen token | care-of keygen token) Kbm = SHA1 (home keygen token | care-of keygen token)
A Binding Update may also be used to delete a previously established A Binding Update may also be used to delete a previously established
binding (Section 6.1.7). In this case, the care-of keygen token is binding (Section 6.1.7). In this case, the care-of keygen token is
not used. Instead, the binding management key is generated as not used. Instead, the binding management key is generated as
follows: follows:
Kbm = SHA1(home keygen token) Kbm = SHA1(home keygen token)
Note that the correspondent node does not create any state specific Note that the correspondent node does not create any state specific
to the mobile node, until it receives the Binding Update from that to the mobile node, until it receives the Binding Update from that
mobile node. The correspondent node does not maintain the value for mobile node. The correspondent node does not maintain the value for
the binding management key Kbm; it creates Kbm when given the nonce the binding management key Kbm; it creates Kbm when given the nonce
indices and the mobile node's addresses. indices and the mobile node's addresses.
5.2.6 Authorizing Binding Management Messages 5.2.6. Authorizing Binding Management Messages
After the mobile node has created the binding management key (Kbm), After the mobile node has created the binding management key (Kbm),
it can supply a verifiable Binding Update to the correspondent node. it can supply a verifiable Binding Update to the correspondent node.
This section provides an overview of this registration. The below This section provides an overview of this registration. The below
figure shows the message flow. figure shows the message flow.
Mobile node Correspondent node Mobile node Correspondent node
| | | |
| Binding Update (BU) | | Binding Update (BU) |
|---------------------------------------------->| |---------------------------------------------->|
| (MAC, seq#, nonce indices, care-of address) | | (MAC, seq#, nonce indices, care-of address) |
| | | |
| | | |
| Binding Acknowledgement (BA) (if sent) | | Binding Acknowledgement (BA) (if sent) |
|<----------------------------------------------| |<----------------------------------------------|
| (MAC, seq#, status) | | (MAC, seq#, status) |
Binding Update Binding Update
To authorize a Binding Update, the mobile node creates a binding To authorize a Binding Update, the mobile node creates a binding
management key Kbm from the keygen tokens as described in the management key Kbm from the keygen tokens as described in the
previous section. The contents of the Binding Update include the previous section. The contents of the Binding Update include the
following: following:
* Source Address = care-of address * Source Address = care-of address
skipping to change at page 29, line 46 skipping to change at page 28, line 36
+ sequence number (within the Binding Update message header) + sequence number (within the Binding Update message header)
+ First (96, HMAC_SHA1 (Kbm, (care-of address | correspondent + First (96, HMAC_SHA1 (Kbm, (care-of address | correspondent
| BA))) | BA)))
The Binding Acknowledgement contains the same sequence number as The Binding Acknowledgement contains the same sequence number as
the Binding Update. The MAC is computed as described in Section the Binding Update. The MAC is computed as described in Section
6.2.7, using the correspondent node's address as the destination 6.2.7, using the correspondent node's address as the destination
address and the message itself ("BA" above) as the MH Data. address and the message itself ("BA" above) as the MH Data.
Bindings established with correspondent nodes using keys created by Bindings established with correspondent nodes using keys created
way of the return routability procedure MUST NOT exceed by way of the return routability procedure MUST NOT exceed
MAX_RR_BINDING_LIFETIME seconds (see Section 12). MAX_RR_BINDING_LIFETIME seconds (see Section 12).
The value in the Source Address field in the IPv6 header carrying the The value in the Source Address field in the IPv6 header carrying
Binding Update is normally also the care-of address which is used in the Binding Update is normally also the care-of address which is
the binding. However, a different care-of address MAY be specified used in the binding. However, a different care-of address MAY be
by including an Alternate Care-of Address mobility option in the specified by including an Alternate Care-of Address mobility
Binding Update (see Section 6.2.5). When such a message is sent to option in the Binding Update (see Section 6.2.5). When such a
the correspondent node and the return routability procedure is used message is sent to the correspondent node and the return
as the authorization method, the Care-of Test Init and Care-of Test routability procedure is used as the authorization method, the
messages MUST have been performed for the address in the Alternate Care-of Test Init and Care-of Test messages MUST have been
Care-of Address option (not the Source Address). The nonce indices performed for the address in the Alternate Care-of Address option
and MAC value MUST be based on information gained in this test. (not the Source Address). The nonce indices and MAC value MUST be
based on information gained in this test.
Binding Updates may also be sent to delete a previously established Binding Updates may also be sent to delete a previously
binding. In this case, generation of the binding management key established binding. In this case, generation of the binding
depends exclusively on the home keygen token and the care-of nonce management key depends exclusively on the home keygen token and
index is ignored. the care-of nonce index is ignored.
5.2.7 Updating Node Keys and Nonces 5.2.7. Updating Node Keys and Nonces
Correspondent nodes generate nonces at regular intervals. It is Correspondent nodes generate nonces at regular intervals. It is
recommended to keep each nonce (identified by a nonce index) recommended to keep each nonce (identified by a nonce index)
acceptable for at least MAX_TOKEN_LIFETIME seconds (see Section 12) acceptable for at least MAX_TOKEN_LIFETIME seconds (see Section 12)
after it has been first used in constructing a return routability after it has been first used in constructing a return routability
message response. However, the correspondent node MUST NOT accept message response. However, the correspondent node MUST NOT accept
nonces beyond MAX_NONCE_LIFETIME seconds (see Section 12) after the nonces beyond MAX_NONCE_LIFETIME seconds (see Section 12) after the
first use. As the difference between these two constants is 30 first use. As the difference between these two constants is 30
seconds, a convenient way to enforce the above lifetimes is to seconds, a convenient way to enforce the above lifetimes is to
generate a new nonce every 30 seconds. The node can then continue to generate a new nonce every 30 seconds. The node can then continue to
skipping to change at page 30, line 46 skipping to change at page 29, line 35
the beginning or end of the first 30 second period. Note that the the beginning or end of the first 30 second period. Note that the
correspondent node may also attempt to generate new nonces on demand, correspondent node may also attempt to generate new nonces on demand,
or only if the old nonces have been used. This is possible, as long or only if the old nonces have been used. This is possible, as long
as the correspondent node keeps track of how long a time ago the as the correspondent node keeps track of how long a time ago the
nonces were used for the first time, and does not generate new nonces nonces were used for the first time, and does not generate new nonces
on every return routability request. on every return routability request.
Due to resource limitations, rapid deletion of bindings, or reboots Due to resource limitations, rapid deletion of bindings, or reboots
the correspondent node may not in all cases recognize the nonces that the correspondent node may not in all cases recognize the nonces that
the tokens were based on. If a nonce index is unrecognized, the the tokens were based on. If a nonce index is unrecognized, the
correspondent node replies with an an error code in the Binding correspondent node replies with an error code in the Binding
Acknowledgement (either 136, 137, or 138 as discussed in Section Acknowledgement (either 136, 137, or 138 as discussed in Section
6.1.8). The mobile node can then retry the return routability 6.1.8). The mobile node can then retry the return routability
procedure. procedure.
An update of Kcn SHOULD be done at the same time as an update of a An update of Kcn SHOULD be done at the same time as an update of a
nonce, so that nonce indices can identify both the nonce and the key. nonce, so that nonce indices can identify both the nonce and the key.
Old Kcn values have to be therefore remembered as long as old nonce Old Kcn values have to be therefore remembered as long as old nonce
values. values.
Given that the tokens are normally expected to be usable for Given that the tokens are normally expected to be usable for
MAX_TOKEN_LIFETIME seconds, the mobile node MAY use them beyond a MAX_TOKEN_LIFETIME seconds, the mobile node MAY use them beyond a
single run of the return routability procedure until single run of the return routability procedure until
MAX_TOKEN_LIFETIME expires. After this the mobile node SHOULD NOT MAX_TOKEN_LIFETIME expires. After this the mobile node SHOULD NOT
use the tokens. A fast moving mobile node MAY reuse a recent home use the tokens. A fast moving mobile node MAY reuse a recent home
keygen token from a correspondent node when moving to a new location, keygen token from a correspondent node when moving to a new location,
and just acquire a new care-of keygen token to show routability in and just acquire a new care-of keygen token to show routability in
skipping to change at page 31, line 25 skipping to change at page 30, line 13
the new location. the new location.
While this does not save the number of round-trips due to the While this does not save the number of round-trips due to the
simultaneous processing of home and care-of return routability tests, simultaneous processing of home and care-of return routability tests,
there are fewer messages being exchanged, and a potentially long there are fewer messages being exchanged, and a potentially long
round-trip through the home agent is avoided. Consequently, this round-trip through the home agent is avoided. Consequently, this
optimization is often useful. A mobile node that has multiple home optimization is often useful. A mobile node that has multiple home
addresses, MAY also use the same care-of keygen token for Binding addresses, MAY also use the same care-of keygen token for Binding
Updates concerning all of these addresses. Updates concerning all of these addresses.
5.2.8 Preventing Replay Attacks 5.2.8. Preventing Replay Attacks
The return routability procedure also protects the participants The return routability procedure also protects the participants
against replayed Binding Updates through the use of the sequence against replayed Binding Updates through the use of the sequence
number and a MAC. Care must be taken when removing bindings at the number and a MAC. Care must be taken when removing bindings at the
correspondent node, however. Correspondent nodes must retain correspondent node, however. Correspondent nodes must retain
bindings and the associated sequence number information at least as bindings and the associated sequence number information at least as
long as the nonces used in the authorization of the binding are still long as the nonces used in the authorization of the binding are still
valid. Alternatively, if memory is very constrained, the valid. Alternatively, if memory is very constrained, the
correspondent node MAY invalidate the nonces that were used for the correspondent node MAY invalidate the nonces that were used for the
binding being deleted (or some larger group of nonces that they binding being deleted (or some larger group of nonces that they
belong to). This may, however, impact the ability to accept Binding belong to). This may, however, impact the ability to accept Binding
Updates from mobile nodes that have recently received keygen tokens. Updates from mobile nodes that have recently received keygen tokens.
This alternative is therefore recommended only as a last measure. This alternative is therefore recommended only as a last measure.
5.3 Dynamic Home Agent Address Discovery 5.3. Dynamic Home Agent Address Discovery
No security is required for dynamic home agent address discovery. No security is required for dynamic home agent address discovery.
5.4 Mobile Prefix Discovery 5.4. Mobile Prefix Discovery
The mobile node and the home agent SHOULD use an IPsec security The mobile node and the home agent SHOULD use an IPsec security
association to protect the integrity and authenticity of the Mobile association to protect the integrity and authenticity of the Mobile
Prefix Solicitations and Advertisements. Both the mobile nodes and Prefix Solicitations and Advertisements. Both the mobile nodes and
the home agents MUST support and SHOULD use the Encapsulating the home agents MUST support and SHOULD use the Encapsulating
Security Payload (ESP) header in transport mode with a non-NULL Security Payload (ESP) header in transport mode with a non-NULL
payload authentication algorithm to provide data origin payload authentication algorithm to provide data origin
authentication, connectionless integrity and optional anti-replay authentication, connectionless integrity and optional anti-replay
protection. protection.
5.5 Payload Packets 5.5. Payload Packets
Payload packets exchanged with mobile nodes can be protected in the Payload packets exchanged with mobile nodes can be protected in the
usual manner, in the same way as stationary hosts can protect them. usual manner, in the same way as stationary hosts can protect them.
However, Mobile IPv6 introduces the Home Address destination option, However, Mobile IPv6 introduces the Home Address destination option,
a routing header, and tunneling headers in the payload packets. In a routing header, and tunneling headers in the payload packets. In
the following we define the security measures taken to protect these, the following we define the security measures taken to protect these,
and to prevent their use in attacks against other parties. and to prevent their use in attacks against other parties.
This specification limits the use of the Home Address destination This specification limits the use of the Home Address destination
option to the situation where the correspondent node already has a option to the situation where the correspondent node already has a
skipping to change at page 32, line 35 skipping to change at page 31, line 25
ensuring proper use of source addresses, and optional cryptographic ensuring proper use of source addresses, and optional cryptographic
protection. The mobile node verifies that the outer IP address protection. The mobile node verifies that the outer IP address
corresponds to its home agent. The home agent verifies that the corresponds to its home agent. The home agent verifies that the
outer IP address corresponds to the current location of the mobile outer IP address corresponds to the current location of the mobile
node (Binding Updates sent to the home agents are secure). The home node (Binding Updates sent to the home agents are secure). The home
agent identifies the mobile node through the source address of the agent identifies the mobile node through the source address of the
inner packet. (Typically, this is the home address of the mobile inner packet. (Typically, this is the home address of the mobile
node, but it can also be a link-local address, as discussed in node, but it can also be a link-local address, as discussed in
Section 10.4.2. To recognize the latter type of addresses, the home Section 10.4.2. To recognize the latter type of addresses, the home
agent requires that the Link-Local Address Compatibility (L) was set agent requires that the Link-Local Address Compatibility (L) was set
in the Binding Update.) These measures protect the tunnels against in the Binding Update.) These measures protect the tunnels against
vulnerabilities discussed in Section 15.1. vulnerabilities discussed in Section 15.1.
For traffic tunneled via the home agent, additional IPsec ESP For traffic tunneled via the home agent, additional IPsec ESP
encapsulation MAY be supported and used. If multicast group encapsulation MAY be supported and used. If multicast group
membership control protocols or stateful address autoconfiguration membership control protocols or stateful address autoconfiguration
protocols are supported, payload data protection MUST be supported. protocols are supported, payload data protection MUST be supported.
6. New IPv6 Protocol, Message Types, and Destination Option 6. New IPv6 Protocol, Message Types, and Destination Option
6.1 Mobility Header 6.1. Mobility Header
The Mobility Header is an extension header used by mobile nodes, The Mobility Header is an extension header used by mobile nodes,
correspondent nodes, and home agents in all messaging related to the correspondent nodes, and home agents in all messaging related to the
creation and management of bindings. The subsections within this creation and management of bindings. The subsections within this
section describe the message types that may be sent using the section describe the message types that may be sent using the
Mobility Header. Mobility Header.
Mobility Header messages MUST NOT be sent with a type 2 routing Mobility Header messages MUST NOT be sent with a type 2 routing
header, except as described in Section 9.5.4 for Binding header, except as described in Section 9.5.4 for Binding
Acknowledgement. Mobility Header messages also MUST NOT be used with Acknowledgement. Mobility Header messages also MUST NOT be used with
a Home Address destination option, except as described in Section a Home Address destination option, except as described in Section
11.7.1 and Section 11.7.2 for Binding Update. Binding Update List or 11.7.1 and Section 11.7.2 for Binding Update. Binding Update List or
Binding Cache information (when present) for the destination MUST NOT Binding Cache information (when present) for the destination MUST NOT
be used in sending Mobility Header messages. That is, Mobility be used in sending Mobility Header messages. That is, Mobility
Header messages bypass both the Binding Cache check described in Header messages bypass both the Binding Cache check described in
Section 9.3.2 and the Binding Update List check described in Section Section 9.3.2 and the Binding Update List check described in Section
11.3.1 which are normally performed for all packets. This applies 11.3.1 which are normally performed for all packets. This applies
even to messages sent to or from a correspondent node which is itself even to messages sent to or from a correspondent node which is itself
a mobile node. a mobile node.
6.1.1 Format 6.1.1. Format
The Mobility Header is identified by a Next Header value of TBD <To The Mobility Header is identified by a Next Header value of 135 in
be assigned by IANA> in the immediately preceding header, and has the the immediately preceding header, and has the following format:
following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Proto | Header Len | MH Type | Reserved | | Payload Proto | Header Len | MH Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Checksum | | | Checksum | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
. . . .
. Message Data . . Message Data .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Payload Proto Payload Proto
8-bit selector. Identifies the type of header immediately 8-bit selector. Identifies the type of header immediately
following the Mobility Header. Uses the same values as the IPv6 following the Mobility Header. Uses the same values as the IPv6
Next Header field [11]. Next Header field [11].
This field is intended to be used by a future extension (see This field is intended to be used by a future extension (see
Appendix B.1). Appendix B.1).
skipping to change at page 34, line 40 skipping to change at page 33, line 22
16-bit unsigned integer. This field contains the checksum of the 16-bit unsigned integer. This field contains the checksum of the
Mobility Header. The checksum is calculated from the octet string Mobility Header. The checksum is calculated from the octet string
consisting of a "pseudo-header" followed by the entire Mobility consisting of a "pseudo-header" followed by the entire Mobility
Header starting with the Payload Proto field. The checksum is the Header starting with the Payload Proto field. The checksum is the
16-bit one's complement of the one's complement sum of this 16-bit one's complement of the one's complement sum of this
string. string.
The pseudo-header contains IPv6 header fields, as specified in The pseudo-header contains IPv6 header fields, as specified in
Section 8.1 of RFC 2460 [11]. The Next Header value used in the Section 8.1 of RFC 2460 [11]. The Next Header value used in the
pseudo-header is TBD <To be assigned by IANA>. The addresses used pseudo-header is 2. The addresses used in the pseudo-header are
in the pseudo-header are the addresses that appear in the Source the addresses that appear in the Source and Destination Address
and Destination Address fields in the IPv6 packet carrying the fields in the IPv6 packet carrying the Mobility Header.
Mobility Header.
Note that the procedures of calculating upper layer checksums Note that the procedures of calculating upper layer checksums
while away from home described in Section 11.3.1 apply even for while away from home described in Section 11.3.1 apply even for
the Mobility Header. If a mobility message has a Home Address the Mobility Header. If a mobility message has a Home Address
destination option, then the checksum calculation uses the home destination option, then the checksum calculation uses the home
address in this option as the value of the IPv6 Source Address address in this option as the value of the IPv6 Source Address
field. The type 2 routing header is treated as explained in [11]. field. The type 2 routing header is treated as explained in [11].
The Mobility Header is considered as the upper layer protocol for The Mobility Header is considered as the upper layer protocol for
the purposes of calculating the pseudo-header. The Upper-Layer the purposes of calculating the pseudo-header. The Upper-Layer
skipping to change at page 35, line 30 skipping to change at page 34, line 9
presence of such options will be indicated by the Header Len field presence of such options will be indicated by the Header Len field
within the message. When the Header Len value is greater than the within the message. When the Header Len value is greater than the
length required for the message specified here, the remaining octets length required for the message specified here, the remaining octets
are interpreted as mobility options. These options include padding are interpreted as mobility options. These options include padding
options that can be used to ensure that other options are aligned options that can be used to ensure that other options are aligned
properly, and that the total length of the message is divisible by 8. properly, and that the total length of the message is divisible by 8.
The encoding and format of defined options are described in Section The encoding and format of defined options are described in Section
6.2. 6.2.
Alignment requirements for the Mobility Header are the same as for Alignment requirements for the Mobility Header are the same as for
any IPv6 protocol Header. That is, they MUST be aligned on an any IPv6 protocol Header. That is, they MUST be aligned on an 8-
8-octet boundary. octet boundary.
6.1.2 Binding Refresh Request Message 6.1.2. Binding Refresh Request Message
The Binding Refresh Request (BRR) message requests a mobile node to The Binding Refresh Request (BRR) message requests a mobile node to
update its mobility binding. This message is sent by correspondent update its mobility binding. This message is sent by correspondent
nodes according to the rules in Section 9.5.5. When a mobile node nodes according to the rules in Section 9.5.5. When a mobile node
receives a packet containing a Binding Refresh Request message it receives a packet containing a Binding Refresh Request message it
processes the message according to the rules in Section 11.7.4. processes the message according to the rules in Section 11.7.4.
The Binding Refresh Request message uses the MH Type value 0. When The Binding Refresh Request message uses the MH Type value 0. When
this value is indicated in the MH Type field, the format of the this value is indicated in the MH Type field, the format of the
Message Data field in the Mobility Header is as follows: Message Data field in the Mobility Header is as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
. Mobility options . . Mobility options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved Reserved
16-bit field reserved for future use. The value MUST be 16-bit field reserved for future use. The value MUST be
initialized to zero by the sender, and MUST be ignored by the initialized to zero by the sender, and MUST be ignored by the
receiver. receiver.
Mobility Options Mobility Options
Variable-length field of such length that the complete Mobility Variable-length field of such length that the complete Mobility
skipping to change at page 36, line 31 skipping to change at page 35, line 15
There MAY be additional information, associated with this Binding There MAY be additional information, associated with this Binding
Refresh Request message that need not be present in all Binding Refresh Request message that need not be present in all Binding
Refresh Request messages sent. Mobility options allow future Refresh Request messages sent. Mobility options allow future
extensions to the format of the Binding Refresh Request message to extensions to the format of the Binding Refresh Request message to
be defined. This specification does not define any options valid be defined. This specification does not define any options valid
for the Binding Refresh Request message. for the Binding Refresh Request message.
If no actual options are present in this message, no padding is If no actual options are present in this message, no padding is
necessary and the Header Len field will be set to 0. necessary and the Header Len field will be set to 0.
6.1.3 Home Test Init Message 6.1.3. Home Test Init Message
A mobile node uses the Home Test Init (HoTI) message to initiate the A mobile node uses the Home Test Init (HoTI) message to initiate the
return routability procedure and request a home keygen token from a return routability procedure and request a home keygen token from a
correspondent node (see Section 11.6.1). The Home Test Init message correspondent node (see Section 11.6.1). The Home Test Init message
uses the MH Type value 1. When this value is indicated in the MH uses the MH Type value 1. When this value is indicated in the MH
Type field, the format of the Message Data field in the Mobility Type field, the format of the Message Data field in the Mobility
Header is as follows: Header is as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Home Init Cookie + + Home Init Cookie +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
. Mobility Options . . Mobility Options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved Reserved
16-bit field reserved for future use. This value MUST be 16-bit field reserved for future use. This value MUST be
initialized to zero by the sender, and MUST be ignored by the initialized to zero by the sender, and MUST be ignored by the
receiver. receiver.
Home Init Cookie Home Init Cookie
64-bit field which contains a random value, the home init cookie. 64-bit field which contains a random value, the home init cookie.
skipping to change at page 37, line 35 skipping to change at page 36, line 18
If no actual options are present in this message, no padding is If no actual options are present in this message, no padding is
necessary and the Header Len field will be set to 1. necessary and the Header Len field will be set to 1.
This message is tunneled through the home agent when the mobile node This message is tunneled through the home agent when the mobile node
is away from home. Such tunneling SHOULD employ IPsec ESP in tunnel is away from home. Such tunneling SHOULD employ IPsec ESP in tunnel
mode between the home agent and the mobile node. This protection is mode between the home agent and the mobile node. This protection is
indicated by the IPsec security policy database. The protection of indicated by the IPsec security policy database. The protection of
Home Test Init messages is unrelated to the requirement to protect Home Test Init messages is unrelated to the requirement to protect
regular payload traffic, which MAY use such tunnels as well. regular payload traffic, which MAY use such tunnels as well.
6.1.4 Care-of Test Init Message 6.1.4. Care-of Test Init Message
A mobile node uses the Care-of Test Init (CoTI) message to initiate A mobile node uses the Care-of Test Init (CoTI) message to initiate
the return routability procedure and request a care-of keygen token the return routability procedure and request a care-of keygen token
from a correspondent node (see Section 11.6.1). The Care-of Test from a correspondent node (see Section 11.6.1). The Care-of Test
Init message uses the MH Type value 2. When this value is indicated Init message uses the MH Type value 2. When this value is indicated
in the MH Type field, the format of the Message Data field in the in the MH Type field, the format of the Message Data field in the
Mobility Header is as follows: Mobility Header is as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Care-of Init Cookie + + Care-of Init Cookie +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
. Mobility Options . . Mobility Options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reserved Reserved
16-bit field reserved for future use. The value MUST be 16-bit field reserved for future use. The value MUST be
initialized to zero by the sender, and MUST be ignored by the initialized to zero by the sender, and MUST be ignored by the
receiver. receiver.
Care-of Init Cookie Care-of Init Cookie
64-bit field which contains a random value, the care-of init 64-bit field which contains a random value, the care-of init
skipping to change at page 38, line 42 skipping to change at page 37, line 17
Variable-length field of such length that the complete Mobility Variable-length field of such length that the complete Mobility
Header is an integer multiple of 8 octets long. This field Header is an integer multiple of 8 octets long. This field
contains zero or more TLV-encoded mobility options. The receiver contains zero or more TLV-encoded mobility options. The receiver
MUST ignore and skip any options which it does not understand. MUST ignore and skip any options which it does not understand.
This specification does not define any options valid for the This specification does not define any options valid for the
Care-of Test Init message. Care-of Test Init message.
If no actual options are present in this message, no padding is If no actual options are present in this message, no padding is
necessary and the Header Len field will be set to 1. necessary and the Header Len field will be set to 1.
6.1.5 Home Test Message 6.1.5. Home Test Message
The Home Test (HoT) message is a response to the Home Test Init The Home Test (HoT) message is a response to the Home Test Init
message, and is sent from the correspondent node to the mobile node message, and is sent from the correspondent node to the mobile node
(see Section 5.2.5). The Home Test message uses the MH Type value 3. (see Section 5.2.5). The Home Test message uses the MH Type value 3.
When this value is indicated in the MH Type field, the format of the When this value is indicated in the MH Type field, the format of the
Message Data field in the Mobility Header is as follows: Message Data field in the Mobility Header is as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Nonce Index | | Home Nonce Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Home Init Cookie + + Home Init Cookie +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Home Keygen Token + + Home Keygen Token +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
. Mobility options . . Mobility options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Home Nonce Index Home Nonce Index
This field will be echoed back by the mobile node to the This field will be echoed back by the mobile node to the
correspondent node in a subsequent Binding Update. correspondent node in a subsequent Binding Update.
Home Init Cookie Home Init Cookie
64-bit field which contains the home init cookie. 64-bit field which contains the home init cookie.
skipping to change at page 39, line 49 skipping to change at page 38, line 22
Variable-length field of such length that the complete Mobility Variable-length field of such length that the complete Mobility
Header is an integer multiple of 8 octets long. This field Header is an integer multiple of 8 octets long. This field
contains zero or more TLV-encoded mobility options. The receiver contains zero or more TLV-encoded mobility options. The receiver
MUST ignore and skip any options which it does not understand. MUST ignore and skip any options which it does not understand.
This specification does not define any options valid for the Home This specification does not define any options valid for the Home
Test message. Test message.
If no actual options are present in this message, no padding is If no actual options are present in this message, no padding is
necessary and the Header Len field will be set to 2. necessary and the Header Len field will be set to 2.
6.1.6 Care-of Test Message 6.1.6. Care-of Test Message
The Care-of Test (CoT) message is a response to the Care-of Test Init The Care-of Test (CoT) message is a response to the Care-of Test Init
message, and is sent from the correspondent node to the mobile node message, and is sent from the correspondent node to the mobile node
(see Section 11.6.2). The Care-of Test message uses the MH Type (see Section 11.6.2). The Care-of Test message uses the MH Type
value 4. When this value is indicated in the MH Type field, the value 4. When this value is indicated in the MH Type field, the
format of the Message Data field in the Mobility Header is as format of the Message Data field in the Mobility Header is as
follows: follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Care-of Nonce Index | | Care-of Nonce Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Care-of Init Cookie + + Care-of Init Cookie +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Care-of Keygen Token + + Care-of Keygen Token +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
. Mobility Options . . Mobility Options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Care-of Nonce Index Care-of Nonce Index
This value will be echoed back by the mobile node to the This value will be echoed back by the mobile node to the
correspondent node in a subsequent Binding Update. correspondent node in a subsequent Binding Update.
Care-of Init Cookie Care-of Init Cookie
64-bit field which contains the care-of init cookie. 64-bit field which contains the care-of init cookie.
skipping to change at page 41, line 5 skipping to change at page 39, line 26
Variable-length field of such length that the complete Mobility Variable-length field of such length that the complete Mobility
Header is an integer multiple of 8 octets long. This field Header is an integer multiple of 8 octets long. This field
contains zero or more TLV-encoded mobility options. The receiver contains zero or more TLV-encoded mobility options. The receiver
MUST ignore and skip any options which it does not understand. MUST ignore and skip any options which it does not understand.
This specification does not define any options valid for the This specification does not define any options valid for the
Care-of Test message. Care-of Test message.
If no actual options are present in this message, no padding is If no actual options are present in this message, no padding is
necessary and the Header Len field will be set to 2. necessary and the Header Len field will be set to 2.
6.1.7 Binding Update Message 6.1.7. Binding Update Message
The Binding Update (BU) message is used by a mobile node to notify The Binding Update (BU) message is used by a mobile node to notify
other nodes of a new care-of address for itself. Binding Updates are other nodes of a new care-of address for itself. Binding Updates are
sent as described in Section 11.7.1 and Section 11.7.2. sent as described in Section 11.7.1 and Section 11.7.2.
The Binding Update uses the MH Type value 5. When this value is The Binding Update uses the MH Type value 5. When this value is
indicated in the MH Type field, the format of the Message Data field indicated in the MH Type field, the format of the Message Data field
in the Mobility Header is as follows: in the Mobility Header is as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # | | Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|H|L|K| Reserved | Lifetime | |A|H|L|K| Reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
. Mobility options . . Mobility options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Acknowledge (A) Acknowledge (A)
The Acknowledge (A) bit is set by the sending mobile node to The Acknowledge (A) bit is set by the sending mobile node to
request a Binding Acknowledgement (Section 6.1.8) be returned upon request a Binding Acknowledgement (Section 6.1.8) be returned upon
receipt of the Binding Update. receipt of the Binding Update.
Home Registration (H) Home Registration (H)
The Home Registration (H) bit is set by the sending mobile node to The Home Registration (H) bit is set by the sending mobile node to
skipping to change at page 42, line 4 skipping to change at page 40, line 25
The Link-Local Address Compatibility (L) bit is set when the home The Link-Local Address Compatibility (L) bit is set when the home
address reported by the mobile node has the same interface address reported by the mobile node has the same interface
identifier as the mobile node's link-local address. identifier as the mobile node's link-local address.
Key Management Mobility Capability (K) Key Management Mobility Capability (K)
If this bit is cleared, the protocol used for establishing the If this bit is cleared, the protocol used for establishing the
IPsec security associations between the mobile node and the home IPsec security associations between the mobile node and the home
agent does not survive movements. It may then have to be rerun. agent does not survive movements. It may then have to be rerun.
(Note that the IPsec security associations themselves are expected (Note that the IPsec security associations themselves are expected
to survive movements.) If manual IPsec configuration is used, the to survive movements.) If manual IPsec configuration is used, the
bit MUST be cleared. bit MUST be cleared.
This bit is valid only in Binding Updates sent to the home agent, This bit is valid only in Binding Updates sent to the home agent,
and MUST be cleared in other Binding Updates. Correspondent nodes and MUST be cleared in other Binding Updates. Correspondent nodes
MUST ignore this bit. MUST ignore this bit.
Reserved Reserved
These fields are unused. They MUST be initialized to zero by the These fields are unused. They MUST be initialized to zero by the
sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
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A 16-bit unsigned integer used by the receiving node to sequence A 16-bit unsigned integer used by the receiving node to sequence
Binding Updates and by the sending node to match a returned Binding Updates and by the sending node to match a returned
Binding Acknowledgement with this Binding Update. Binding Acknowledgement with this Binding Update.
Lifetime Lifetime
16-bit unsigned integer. The number of time units remaining 16-bit unsigned integer. The number of time units remaining
before the binding MUST be considered expired. A value of zero before the binding MUST be considered expired. A value of zero
indicates that the Binding Cache entry for the mobile node MUST be indicates that the Binding Cache entry for the mobile node MUST be
deleted. (In this case the specified care-of address MUST also be deleted. (In this case the specified care-of address MUST also be
set equal to the home address.) One time unit is 4 seconds. set equal to the home address.) One time unit is 4 seconds.
Mobility Options Mobility Options
Variable-length field of such length that the complete Mobility Variable-length field of such length that the complete Mobility
Header is an integer multiple of 8 octets long. This field Header is an integer multiple of 8 octets long. This field
contains zero or more TLV-encoded mobility options. The encoding contains zero or more TLV-encoded mobility options. The encoding
and format of defined options are described in Section 6.2. The and format of defined options are described in Section 6.2. The
receiver MUST ignore and skip any options which it does not receiver MUST ignore and skip any options which it does not
understand. understand.
The following options are valid in a Binding Update: The following options are valid in a Binding Update:
* Binding Authorization Data option (this option is mandatory in * Binding Authorization Data option (this option is mandatory in
Binding Updates sent to a correspondent node) Binding Updates sent to a correspondent node)
* Nonce Indices option. * Nonce Indices option.
* Alternate Care-of Address option * Alternate Care-of Address option
If no options are present in this message, 4 octets of padding is If no options are present in this message, 4 octets of padding are
necessary and the Header Len field will be set to 1. necessary and the Header Len field will be set to 1.
The care-of address is specified either by the Source Address field The care-of address is specified either by the Source Address field
in the IPv6 header or by the Alternate Care-of Address option, if in the IPv6 header or by the Alternate Care-of Address option, if
present. The care-of address MUST be a unicast routable address. present. The care-of address MUST be a unicast routable address.
IPv6 Source Address MUST be a topologically correct source address. IPv6 Source Address MUST be a topologically correct source address.
Binding Updates for a care-of address which is not a unicast routable Binding Updates for a care-of address which is not a unicast routable
address MUST be silently discarded. Similarly, the Binding Update address MUST be silently discarded. Similarly, the Binding Update
MUST be silently discarded if the care-of address appears as a home MUST be silently discarded if the care-of address appears as a home
address in an existing Binding Cache entry, with its current location address in an existing Binding Cache entry, with its current location
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The deletion of a binding can be indicated by setting the Lifetime The deletion of a binding can be indicated by setting the Lifetime
field to 0 and by setting the care-of address equal to the home field to 0 and by setting the care-of address equal to the home
address. In deletion, the generation of the binding management key address. In deletion, the generation of the binding management key
depends exclusively on the home keygen token, as explained in Section depends exclusively on the home keygen token, as explained in Section
5.2.5. (Note that while the senders are required to set both the 5.2.5. (Note that while the senders are required to set both the
Lifetime field to 0 and the care-of address equal to the home Lifetime field to 0 and the care-of address equal to the home
address, Section 9.5.1 rules for receivers are more liberal, and address, Section 9.5.1 rules for receivers are more liberal, and
interpret either condition as a deletion.) interpret either condition as a deletion.)
Correspondent nodes SHOULD NOT expire the Binding Cache entry before Correspondent nodes SHOULD NOT delete the Binding Cache entry before
the lifetime expires, if any application hosted by the correspondent the lifetime expires, if any application hosted by the correspondent
node is still likely to require communication with the mobile node. node is still likely to require communication with the mobile node.
A Binding Cache entry that is deallocated prematurely might cause A Binding Cache entry that is de-allocated prematurely might cause
subsequent packets to be dropped from the mobile node, if they subsequent packets to be dropped from the mobile node, if they
contain the Home Address destination option. This situation is contain the Home Address destination option. This situation is
recoverable, since an Binding Error message is sent to the mobile recoverable, since a Binding Error message is sent to the mobile node
node (see Section 6.1.9); however, it causes unnecessary delay in the (see Section 6.1.9); however, it causes unnecessary delay in the
communications. communications.
6.1.8 Binding Acknowledgement Message 6.1.8. Binding Acknowledgement Message
The Binding Acknowledgement is used to acknowledge receipt of a The Binding Acknowledgement is used to acknowledge receipt of a
Binding Update (Section 6.1.7). This packet is sent as described in Binding Update (Section 6.1.7). This packet is sent as described in
Section 9.5.4 and Section 10.3.1. Section 9.5.4 and Section 10.3.1.
The Binding Acknowledgement has the MH Type value 6. When this value The Binding Acknowledgement has the MH Type value 6. When this value
is indicated in the MH Type field, the format of the Message Data is indicated in the MH Type field, the format of the Message Data
field in the Mobility Header is as follows: field in the Mobility Header is as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status |K| Reserved | | Status |K| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # | Lifetime | | Sequence # | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
. Mobility options . . Mobility options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Key Management Mobility Capability (K) Key Management Mobility Capability (K)
If this bit is cleared, the protocol used by the home agent for If this bit is cleared, the protocol used by the home agent for
establishing the IPsec security associations between the mobile establishing the IPsec security associations between the mobile
node and the home agent does not survive movements. It may then node and the home agent does not survive movements. It may then
have to be rerun. (Note that the IPsec security associations have to be rerun. (Note that the IPsec security associations
themselves are expected to survive movements.) themselves are expected to survive movements.)
Correspondent nodes MUST set the K bit to 0. Correspondent nodes MUST set the K bit to 0.
skipping to change at page 44, line 41 skipping to change at page 43, line 14
Status Status
8-bit unsigned integer indicating the disposition of the Binding 8-bit unsigned integer indicating the disposition of the Binding
Update. Values of the Status field less than 128 indicate that Update. Values of the Status field less than 128 indicate that
the Binding Update was accepted by the receiving node. Values the Binding Update was accepted by the receiving node. Values
greater than or equal to 128 indicate that the Binding Update was greater than or equal to 128 indicate that the Binding Update was
rejected by the receiving node. The following Status values are rejected by the receiving node. The following Status values are
currently defined: currently defined:
0 Binding Update accepted 0 Binding Update accepted
1 Accepted but prefix discovery necessary 1 Accepted but prefix discovery necessary
128 Reason unspecified 128 Reason unspecified
129 Administratively prohibited 129 Administratively prohibited
130 Insufficient resources 130 Insufficient resources
131 Home registration not supported
132 Not home subnet 131 Home registration not supported
133 Not home agent for this mobile node 132 Not home subnet
134 Duplicate Address Detection failed 133 Not home agent for this mobile node
135 Sequence number out of window 134 Duplicate Address Detection failed
136 Expired home nonce index 135 Sequence number out of window
137 Expired care-of nonce index 136 Expired home nonce index
138 Expired nonces 137 Expired care-of nonce index
139 Registration type change disallowed 138 Expired nonces
Up-to-date values of the Status field are to be specified in the 139 Registration type change disallowed
IANA registry of assigned numbers [19].
Up-to-date values of the Status field are to be specified in the IANA
registry of assigned numbers [19].
Sequence # Sequence #
The Sequence Number in the Binding Acknowledgement is copied from The Sequence Number in the Binding Acknowledgement is copied from
the Sequence Number field in the Binding Update. It is used by the Sequence Number field in the Binding Update. It is used by
the mobile node in matching this Binding Acknowledgement with an the mobile node in matching this Binding Acknowledgement with an
outstanding Binding Update. outstanding Binding Update.
Lifetime Lifetime
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Acknowledgements sent. Mobility options allow future extensions Acknowledgements sent. Mobility options allow future extensions
to the format of the Binding Acknowledgement to be defined. The to the format of the Binding Acknowledgement to be defined. The
following options are valid for the Binding Acknowledgement: following options are valid for the Binding Acknowledgement:
* Binding Authorization Data option (this option is mandatory in * Binding Authorization Data option (this option is mandatory in
Binding Acknowledgements sent by a correspondent node, except Binding Acknowledgements sent by a correspondent node, except
where otherwise noted in Section 9.5.4) where otherwise noted in Section 9.5.4)
* Binding Refresh Advice option * Binding Refresh Advice option
If no options are present in this message, 4 octets of padding is If no options are present in this message, 4 octets of padding are
necessary and the Header Len field will be set to 1. necessary and the Header Len field will be set to 1.
6.1.9 Binding Error Message 6.1.9. Binding Error Message
The Binding Error (BE) message is used by the correspondent node to The Binding Error (BE) message is used by the correspondent node to
signal an error related to mobility, such as an inappropriate attempt signal an error related to mobility, such as an inappropriate attempt
to use the Home Address destination option without an existing to use the Home Address destination option without an existing
binding; see Section 9.3.3 for details. binding; see Section 9.3.3 for details.
The Binding Error message uses the MH Type value 7. When this value The Binding Error message uses the MH Type value 7. When this value
is indicated in the MH Type field, the format of the Message Data is indicated in the MH Type field, the format of the Message Data
field in the Mobility Header is as follows: field in the Mobility Header is as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status | Reserved | | Status | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Home Address + + Home Address +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. Mobility Options . . Mobility Options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Status Status
8-bit unsigned integer indicating the reason for this message. 8-bit unsigned integer indicating the reason for this message.
The following values are currently defined: The following values are currently defined:
1 Unknown binding for Home Address destination option 1 Unknown binding for Home Address destination option
2 Unrecognized MH Type value 2 Unrecognized MH Type value
Reserved Reserved
A 8-bit field reserved for future use. The value MUST be A 8-bit field reserved for future use. The value MUST be
initialized to zero by the sender, and MUST be ignored by the initialized to zero by the sender, and MUST be ignored by the
receiver. receiver.
Home Address Home Address
The home address that was contained in the Home Address The home address that was contained in the Home Address
skipping to change at page 47, line 40 skipping to change at page 46, line 23
Error message that need not be present in all Binding Error Error message that need not be present in all Binding Error
messages sent. Mobility options allow future extensions to the messages sent. Mobility options allow future extensions to the
format of the format of the Binding Error message to be defined. format of the format of the Binding Error message to be defined.
The encoding and format of defined options are described in The encoding and format of defined options are described in
Section 6.2. This specification does not define any options valid Section 6.2. This specification does not define any options valid
for the Binding Error message. for the Binding Error message.
If no actual options are present in this message, no padding is If no actual options are present in this message, no padding is
necessary and the Header Len field will be set to 2. necessary and the Header Len field will be set to 2.
6.2 Mobility Options 6.2. Mobility Options
Mobility messages can include zero or more mobility options. This Mobility messages can include zero or more mobility options. This
allows optional fields that may not be needed in every use of a allows optional fields that may not be needed in every use of a
particular Mobility Header, as well as future extensions to the particular Mobility Header, as well as future extensions to the
format of the messages. Such options are included in the Message format of the messages. Such options are included in the Message
Data field of the message itself, after the fixed portion of the Data field of the message itself, after the fixed portion of the
message data specified in the message subsections of Section 6.1. message data specified in the message subsections of Section 6.1.
The presence of such options will be indicated by the Header Len of The presence of such options will be indicated by the Header Len of
the Mobility Header. If included, the Binding Authorization Data the Mobility Header. If included, the Binding Authorization Data
option (Section 6.2.7) MUST be the last option and MUST NOT have option (Section 6.2.7) MUST be the last option and MUST NOT have
trailing padding. Otherwise, options can be placed in any order. trailing padding. Otherwise, options can be placed in any order.
6.2.1 Format 6.2.1. Format
Mobility options are encoded within the remaining space of the Mobility options are encoded within the remaining space of the
Message Data field of a mobility message, using a type-length-value Message Data field of a mobility message, using a type-length-value
(TLV) format as follows: (TLV) format as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Length | Option Data... | Option Type | Option Length | Option Data...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Type Option Type
8-bit identifier of the type of mobility option. When processing 8-bit identifier of the type of mobility option. When processing
a Mobility Header containing an option for which the Option Type a Mobility Header containing an option for which the Option Type
value is not recognized by the receiver, the receiver MUST quietly value is not recognized by the receiver, the receiver MUST quietly
ignore and skip over the option, correctly handling any remaining ignore and skip over the option, correctly handling any remaining
options in the message. options in the message.
Option Length Option Length
skipping to change at page 48, line 48 skipping to change at page 47, line 35
Implementations MUST silently ignore any mobility options that they Implementations MUST silently ignore any mobility options that they
do not understand. do not understand.
Mobility options may have alignment requirements. Following the Mobility options may have alignment requirements. Following the
convention in IPv6, these options are aligned in a packet so that convention in IPv6, these options are aligned in a packet so that
multi-octet values within the Option Data field of each option fall multi-octet values within the Option Data field of each option fall
on natural boundaries (i.e., fields of width n octets are placed at on natural boundaries (i.e., fields of width n octets are placed at
an integer multiple of n octets from the start of the header, for n = an integer multiple of n octets from the start of the header, for n =
1, 2, 4, or 8) [11]. 1, 2, 4, or 8) [11].
6.2.2 Pad1 6.2.2. Pad1
The Pad1 option does not have any alignment requirements. Its format The Pad1 option does not have any alignment requirements. Its format
is as follows: is as follows:
0 0
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| Type = 0 | | Type = 0 |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
NOTE! the format of the Pad1 option is a special case - it has NOTE! the format of the Pad1 option is a special case - it has
neither Option Length nor Option Data fields. neither Option Length nor Option Data fields.
The Pad1 option is used to insert one octet of padding in the The Pad1 option is used to insert one octet of padding in the
Mobility Options area of a Mobility Header. If more than one octet Mobility Options area of a Mobility Header. If more than one octet
of padding is required, the PadN option, described next, should be of padding is required, the PadN option, described next, should be
used rather than multiple Pad1 options. used rather than multiple Pad1 options.
6.2.3 PadN 6.2.3. PadN
The PadN option does not have any alignment requirements. Its format The PadN option does not have any alignment requirements. Its format
is as follows: is as follows:
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
| Type = 1 | Option Length | Option Data | Type = 1 | Option Length | Option Data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - -
The PadN option is used to insert two or more octets of padding in The PadN option is used to insert two or more octets of padding in
the Mobility Options area of a mobility message. For N octets of the Mobility Options area of a mobility message. For N octets of
padding, the Option Length field contains the value N-2, and the padding, the Option Length field contains the value N-2, and the
Option Data consists of N-2 zero-valued octets. PadN Option data Option Data consists of N-2 zero-valued octets. PadN Option data
MUST be ignored by the receiver. MUST be ignored by the receiver.
6.2.4 Binding Refresh Advice 6.2.4. Binding Refresh Advice
The Binding Refresh Advice option has an alignment requirement of 2n. The Binding Refresh Advice option has an alignment requirement of 2n.
Its format is as follows: Its format is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 2 | Length = 2 | | Type = 2 | Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Refresh Interval | | Refresh Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Binding Refresh Advice option is only valid in the Binding The Binding Refresh Advice option is only valid in the Binding
Acknowledgement, and only on Binding Acknowledgements sent from the Acknowledgement, and only on Binding Acknowledgements sent from the
mobile node's home agent in reply to a home registration. The mobile node's home agent in reply to a home registration. The
Refresh Interval is measured in units of four seconds, and indicates Refresh Interval is measured in units of four seconds, and indicates
how long before the mobile node SHOULD send a new home registration remaining time until the mobile node SHOULD send a new home
to the home agent. The Refresh Interval MUST be set to indicate a registration to the home agent. The Refresh Interval MUST be set to
smaller time interval than the Lifetime value of the Binding indicate a smaller time interval than the Lifetime value of the
Acknowledgement. Binding Acknowledgement.
6.2.5 Alternate Care-of Address 6.2.5. Alternate Care-of Address
The Alternate Care-of Address option has an alignment requirement of The Alternate Care-of Address option has an alignment requirement of
8n+6. Its format is as follows: 8n+6. Its format is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 3 | Length = 16 | | Type = 3 | Length = 16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Alternate Care-of Address + + Alternate Care-of Address +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Normally, a Binding Update specifies the desired care-of address in Normally, a Binding Update specifies the desired care-of address in
the Source Address field of the IPv6 header. However, this is not the Source Address field of the IPv6 header. However, this is not
possible in some cases, such as when the mobile node wishes to possible in some cases, such as when the mobile node wishes to
indicate a care-of address which it cannot use as a topologically indicate a care-of address which it cannot use as a topologically
correct source address (Section 6.1.7 and Section 11.7.2) or when the correct source address (Section 6.1.7 and Section 11.7.2) or when the
used security mechanism does not protect the IPv6 header (Section used security mechanism does not protect the IPv6 header (Section
11.7.1). 11.7.1).
The Alternate Care-of Address option is provided for these The Alternate Care-of Address option is provided for these
situations. This option is valid only in Binding Update. The situations. This option is valid only in Binding Update. The
Alternate Care-of Address field contains an address to use as the Alternate Care-of Address field contains an address to use as the
care-of address for the binding, rather than using the Source Address care-of address for the binding, rather than using the Source Address
of the packet as the care-of address. of the packet as the care-of address.
6.2.6 Nonce Indices 6.2.6. Nonce Indices
The Nonce Indices option has an alignment requirement of 2n. Its The Nonce Indices option has an alignment requirement of 2n. Its
format is as follows: format is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 4 | Length = 4 | | Type = 4 | Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Nonce Index | Care-of Nonce Index | | Home Nonce Index | Care-of Nonce Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Nonce Indices option is valid only in the Binding Update message The Nonce Indices option is valid only in the Binding Update message
sent to a correspondent node, and only when present together with a sent to a correspondent node, and only when present together with a
Binding Authorization Data option. When the correspondent node Binding Authorization Data option. When the correspondent node
authorizes the Binding Update, it needs to produce home and care-of authorizes the Binding Update, it needs to produce home and care-of
keygen tokens from its stored random nonce values. keygen tokens from its stored random nonce values.
The Home Nonce Index field tells the correspondent node which nonce The Home Nonce Index field tells the correspondent node which nonce
value to use when producing the home keygen token. value to use when producing the home keygen token.
The Care-of Nonce Index field is ignored in requests to delete a The Care-of Nonce Index field is ignored in requests to delete a
binding. Otherwise, it tells the correspondent node which nonce binding. Otherwise, it tells the correspondent node which nonce
value to use when producing the care-of keygen token. value to use when producing the care-of keygen token.
6.2.7 Binding Authorization Data 6.2.7. Binding Authorization Data
The Binding Authorization Data option does not have alignment The Binding Authorization Data option does not have alignment
requirements as such. However, since this option must be the last requirements as such. However, since this option must be the last
mobility option, an implicit alignment requirement is 8n + 2. The mobility option, an implicit alignment requirement is 8n + 2. The
format of this option is as follows: format of this option is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 5 | Option Length | | Type = 5 | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| Authenticator | | Authenticator |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Binding Authorization Data option is valid in the Binding Update The Binding Authorization Data option is valid in the Binding Update
and Binding Acknowledgement. and Binding Acknowledgement.
The Option Length field contains the length of the authenticator in The Option Length field contains the length of the authenticator in
octets. octets.
The Authenticator field contains a cryptographic value which can be The Authenticator field contains a cryptographic value which can be
used to determine that the message in question comes from the right used to determine that the message in question comes from the right
authority. Rules for calculating this value depend on the used authority. Rules for calculating this value depends on the used
authorization procedure. authorization procedure.
For the return routability procedure, this option can appear in the For the return routability procedure, this option can appear in the
Binding Update and Binding Acknowledgements. Rules for calculating Binding Update and Binding Acknowledgements. Rules for calculating
the Authenticator value are the following: the Authenticator value are the following:
Mobility Data = care-of address | correspondent | MH Data Mobility Data = care-of address | correspondent | MH Data
Authenticator = First (96, HMAC_SHA1 (Kbm, Mobility Data)) Authenticator = First (96, HMAC_SHA1 (Kbm, Mobility Data))
Where | denotes concatenation and "correspondent" is the IPv6 address Where | denotes concatenation. "Care-of address" is the care-of
of the correspondent node. Note that, if the message is sent to a address which will be registered for the mobile node if the Binding
destination which is itself mobile, the "correspondent" address may Update succeeds, or the home address of the mobile node if this
not be the address found in the Destination Address field of the IPv6 option is used in de-registration. Note also that this address might
header; instead the home address from the type 2 Routing header be different from the source address of the Binding Update message,
should be used. if the Alternative Care-of Address mobility option is used, or when
the lifetime of the binding is set to zero.
The "correspondent" is the IPv6 address of the correspondent node.
Note that, if the message is sent to a destination which is itself
mobile, the "correspondent" address may not be the address found in
the Destination Address field of the IPv6 header; instead the home
address from the type 2 Routing header should be used.
"MH Data" is the content of the Mobility Header, excluding the "MH Data" is the content of the Mobility Header, excluding the
Authenticator field itself. The Authenticator value is calculated as Authenticator field itself. The Authenticator value is calculated as
if the Checksum field in the Mobility Header was zero. The Checksum if the Checksum field in the Mobility Header was zero. The Checksum
in the transmitted packet is still calculated in the usual manner, in the transmitted packet is still calculated in the usual manner,
with the calculated Authenticator being a part of the packet with the calculated Authenticator being a part of the packet
protected by the Checksum. Kbm is the binding management key, which protected by the Checksum. Kbm is the binding management key, which
is typically created using nonces provided by the correspondent node is typically created using nonces provided by the correspondent node
(see Section 9.4). Note that while the contents of a potential Home (see Section 9.4). Note that while the contents of a potential Home
Address destination option are not covered in this formula, the rules Address destination option are not covered in this formula, the rules
for the calculation of the Kbm do take the home address in account. for the calculation of the Kbm do take the home address in account.
This ensures that the MAC will be different for different home This ensures that the MAC will be different for different home
addresses. addresses.
The first 96 bits from the MAC result are used as the Authenticator The first 96 bits from the MAC result are used as the Authenticator
field. field.
6.3 Home Address Option 6.3. Home Address Option
The Home Address option is carried by the Destination Option The Home Address option is carried by the Destination Option
extension header (Next Header value = 60). It is used in a packet extension header (Next Header value = 60). It is used in a packet
sent by a mobile node while away from home, to inform the recipient sent by a mobile node while away from home, to inform the recipient
of the mobile node's home address. of the mobile node's home address.
The Home Address option is encoded in type-length-value (TLV) format The Home Address option is encoded in type-length-value (TLV) format
as follows: as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Length | | Option Type | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Home Address + + Home Address +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Type Option Type
201 = 0xC9 201 = 0xC9
Option Length Option Length
8-bit unsigned integer. Length of the option, in octets, 8-bit unsigned integer. Length of the option, in octets,
excluding the Option Type and Option Length fields. This field excluding the Option Type and Option Length fields. This field
MUST be set to 16. MUST be set to 16.
skipping to change at page 53, line 48 skipping to change at page 52, line 51
option, these three bits are set to 110. This indicates the option, these three bits are set to 110. This indicates the
following processing requirements: following processing requirements:
o Any IPv6 node that does not recognize the Option Type must discard o Any IPv6 node that does not recognize the Option Type must discard
the packet, and if the packet's Destination Address was not a the packet, and if the packet's Destination Address was not a
multicast address, return an ICMP Parameter Problem, Code 2, multicast address, return an ICMP Parameter Problem, Code 2,
message to the packet's Source Address. The Pointer field in the message to the packet's Source Address. The Pointer field in the
ICMP message SHOULD point at the Option Type field. Otherwise, ICMP message SHOULD point at the Option Type field. Otherwise,
for multicast addresses, the ICMP message MUST NOT be sent. for multicast addresses, the ICMP message MUST NOT be sent.
o The data within the option cannot change en-route to the packet's o The data within the option cannot change en route to the packet's
final destination. final destination.
The Home Address option MUST be placed as follows: The Home Address option MUST be placed as follows:
o After the routing header, if that header is present o After the routing header, if that header is present
o Before the Fragment Header, if that header is present o Before the Fragment Header, if that header is present
o Before the AH Header or ESP Header, if either one of those headers o Before the AH Header or ESP Header, if either one of those headers
is present are present
For each IPv6 packet header, the Home Address Option MUST NOT appear For each IPv6 packet header, the Home Address Option MUST NOT appear
more than once. However, an encapsulated packet [15] MAY contain a more than once. However, an encapsulated packet [15] MAY contain a
separate Home Address option associated with each encapsulating IP separate Home Address option associated with each encapsulating IP
header. header.
The inclusion of a Home Address destination option in a packet The inclusion of a Home Address destination option in a packet
affects the receiving node's processing of only this single packet. affects the receiving node's processing of only this single packet.
No state is created or modified in the receiving node as a result of No state is created or modified in the receiving node as a result of
receiving a Home Address option in a packet. In particular, the receiving a Home Address option in a packet. In particular, the
presence of a Home Address option in a received packet MUST NOT alter presence of a Home Address option in a received packet MUST NOT alter
the contents of the receiver's Binding Cache and MUST NOT cause any the contents of the receiver's Binding Cache and MUST NOT cause any
changes in the routing of subsequent packets sent by this receiving changes in the routing of subsequent packets sent by this receiving
node. node.
6.4 Type 2 Routing Header 6.4. Type 2 Routing Header
Mobile IPv6 defines a new routing header variant, the type 2 routing Mobile IPv6 defines a new routing header variant, the type 2 routing
header, to allow the packet to be routed directly from a header, to allow the packet to be routed directly from a
correspondent to the mobile node's care-of address. The mobile correspondent to the mobile node's care-of address. The mobile
node's care-of address is inserted into the IPv6 Destination Address node's care-of address is inserted into the IPv6 Destination Address
field. Once the packet arrives at the care-of address, the mobile field. Once the packet arrives at the care-of address, the mobile
node retrieves its home address from the routing header, and this is node retrieves its home address from the routing header, and this is
used as the final destination address for the packet. used as the final destination address for the packet.
The new routing header uses a different type than defined for The new routing header uses a different type than defined for
skipping to change at page 54, line 49 skipping to change at page 54, line 5
header type (type 2) is restricted to carry only one IPv6 address. header type (type 2) is restricted to carry only one IPv6 address.
All IPv6 nodes which process this routing header MUST verify that the All IPv6 nodes which process this routing header MUST verify that the
address contained within is the node's own home address in order to address contained within is the node's own home address in order to
prevent packets from being forwarded outside the node. The IP prevent packets from being forwarded outside the node. The IP
address contained in the routing header, since it is the mobile address contained in the routing header, since it is the mobile
node's home address, MUST be a unicast routable address. node's home address, MUST be a unicast routable address.
Furthermore, if the scope of the home address is smaller than the Furthermore, if the scope of the home address is smaller than the
scope of the care-of address, the mobile node MUST discard the packet scope of the care-of address, the mobile node MUST discard the packet
(see Section 4.6). (see Section 4.6).
6.4.1 Format 6.4.1. Format
The type 2 routing header has the following format: The type 2 routing header has the following format:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Hdr Ext Len=2 | Routing Type=2|Segments Left=1| | Next Header | Hdr Ext Len=2 | Routing Type=2|Segments Left=1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Home Address + + Home Address +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header Next Header
8-bit selector. Identifies the type of header immediately 8-bit selector. Identifies the type of header immediately
following the routing header. Uses the same values as the IPv6 following the routing header. Uses the same values as the IPv6
Next Header field [11]. Next Header field [11].
Hdr Ext Len Hdr Ext Len
2 (8-bit unsigned integer); length of the routing header in 2 (8-bit unsigned integer); length of the routing header in 8-
8-octet units, not including the first 8 octets octet units, not including the first 8 octets.
Routing Type Routing Type
2 (8-bit unsigned integer). 2 (8-bit unsigned integer).
Segments Left Segments Left
1 (8-bit unsigned integer). 1 (8-bit unsigned integer).
Reserved Reserved
32-bit reserved field. The value MUST be initialized to zero by 32-bit reserved field. The value MUST be initialized to zero by
the sender, and MUST be ignored by the receiver. the sender, and MUST be ignored by the receiver.
Home Address Home Address
The Home Address of the destination Mobile Node. The Home Address of the destination Mobile Node.
skipping to change at page 56, line 19 skipping to change at page 55, line 26
as an original packet by the outer (type 0) routing header as an original packet by the outer (type 0) routing header
construction process. construction process.
In addition, the general procedures defined by IPv6 for routing In addition, the general procedures defined by IPv6 for routing
headers suggest that a received routing header MAY be automatically headers suggest that a received routing header MAY be automatically
"reversed" to construct a routing header for use in any response "reversed" to construct a routing header for use in any response
packets sent by upper-layer protocols, if the received packet is packets sent by upper-layer protocols, if the received packet is
authenticated [6]. This MUST NOT be done automatically for type 2 authenticated [6]. This MUST NOT be done automatically for type 2
routing headers. routing headers.
6.5 ICMP Home Agent Address Discovery Request Message 6.5. ICMP Home Agent Address Discovery Request Message
The ICMP Home Agent Address Discovery Request message is used by a The ICMP Home Agent Address Discovery Request message is used by a
mobile node to initiate the dynamic home agent address discovery mobile node to initiate the dynamic home agent address discovery
mechanism, as described in Section 11.4.1. The mobile node sends the mechanism, as described in Section 11.4.1. The mobile node sends the
Home Agent Address Discovery Request message to the Mobile IPv6 Home Agent Address Discovery Request message to the Mobile IPv6
Home-Agents anycast address [16] for its own home subnet prefix. Home-Agents anycast address [16] for its own home subnet prefix.
(Note that the currently defined anycast addresses may not work with (Note that the currently defined anycast addresses may not work with
all prefix lengths other than those defined in RFC 2373 [3, 35].) all prefix lengths other than those defined in RFC 2373 [3, 35].)
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum | | Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | Reserved | | Identifier | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type Type
150 <To Be Assigned by IANA> 144
Code Code
0 0
Checksum Checksum
The ICMP checksum [14]. The ICMP checksum [14].
Identifier Identifier
skipping to change at page 57, line 22 skipping to change at page 56, line 30
The Source Address of the Home Agent Address Discovery Request The Source Address of the Home Agent Address Discovery Request
message packet is typically one of the mobile node's current care-of message packet is typically one of the mobile node's current care-of
addresses. At the time of performing this dynamic home agent address addresses. At the time of performing this dynamic home agent address
discovery procedure, it is likely that the mobile node is not discovery procedure, it is likely that the mobile node is not
registered with any home agent. Therefore, neither the nature of the registered with any home agent. Therefore, neither the nature of the
address nor the identity of the mobile node can be established at address nor the identity of the mobile node can be established at
this time. The home agent MUST then return the Home Agent Address this time. The home agent MUST then return the Home Agent Address
Discovery Reply message directly to the Source Address chosen by the Discovery Reply message directly to the Source Address chosen by the
mobile node. mobile node.
6.6 ICMP Home Agent Address Discovery Reply Message 6.6. ICMP Home Agent Address Discovery Reply Message
The ICMP Home Agent Address Discovery Reply message is used by a home The ICMP Home Agent Address Discovery Reply message is used by a home
agent to respond to a mobile node that uses the dynamic home agent agent to respond to a mobile node that uses the dynamic home agent
address discovery mechanism, as described in Section 10.5. address discovery mechanism, as described in Section 10.5.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum | | Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | Reserved | | Identifier | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
. . . .
. Home Agent Addresses . . Home Agent Addresses .
. . . .
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type Type
151 <To Be Assigned by IANA> 145
Code Code
0 0
Checksum Checksum
The ICMP checksum [14]. The ICMP checksum [14].
Identifier Identifier
skipping to change at page 58, line 22 skipping to change at page 57, line 30
Request message. Request message.
Reserved Reserved
This field is unused. It MUST be initialized to zero by the This field is unused. It MUST be initialized to zero by the
sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
Home Agent Addresses Home Agent Addresses
A list of addresses of home agents on the home link for the mobile A list of addresses of home agents on the home link for the mobile
node. The number of addresses present in the list is indicated by node. The number of addresses presented in the list is indicated
the remaining length of the IPv6 packet carrying the Home Agent by the remaining length of the IPv6 packet carrying the Home Agent
Address Discovery Reply message. Address Discovery Reply message.
6.7 ICMP Mobile Prefix Solicitation Message Format 6.7. ICMP Mobile Prefix Solicitation Message Format
The ICMP Mobile Prefix Solicitation Message is sent by a mobile node The ICMP Mobile Prefix Solicitation Message is sent by a mobile node
to its home agent while it is away from home. The purpose of the to its home agent while it is away from home. The purpose of the
message is to solicit a Mobile Prefix Advertisement from the home message is to solicit a Mobile Prefix Advertisement from the home
agent, which will allow the mobile node to gather prefix information agent, which will allow the mobile node to gather prefix information
about its home network. This information can be used to configure about its home network. This information can be used to configure
and update home address(es) according to changes in prefix and update home address(es) according to changes in prefix
information supplied by the home agent. information supplied by the home agent.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum | | Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | Reserved | | Identifier | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IP Fields: IP Fields:
Source Address Source Address
The mobile node's care-of address. The mobile node's care-of address.
Destination Address Destination Address
The address of the mobile node's home agent. This home agent must The address of the mobile node's home agent. This home agent must
be on the link which the mobile node wishes to learn prefix be on the link that the mobile node wishes to learn prefix
information about. information about.
Hop Limit Hop Limit
Set to an initial hop limit value, similarly to any other unicast Set to an initial hop limit value, similarly to any other unicast
packet sent by the mobile node. packet sent by the mobile node.
Destination Option: Destination Option:
A Home Address destination option MUST be included. A Home Address destination option MUST be included.
ESP header: ESP header:
IPsec headers MUST be supported and SHOULD be used as described in IPsec headers MUST be supported and SHOULD be used as described in
Section 5.4. Section 5.4.
ICMP Fields: ICMP Fields:
Type Type
152 <To Be Assigned by IANA> 146
Code Code
0 0
Checksum Checksum
The ICMP checksum [14]. The ICMP checksum [14].
Identifier Identifier
skipping to change at page 60, line 12 skipping to change at page 59, line 17
This field is unused. It MUST be initialized to zero by the This field is unused. It MUST be initialized to zero by the
sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
The Mobile Prefix Solicitation messages may have options. These The Mobile Prefix Solicitation messages may have options. These
options MUST use the option format defined in RFC 2461 [12]. This options MUST use the option format defined in RFC 2461 [12]. This
document does not define any option types for the Mobile Prefix document does not define any option types for the Mobile Prefix
Solicitation message, but future documents may define new options. Solicitation message, but future documents may define new options.
Home agents MUST silently ignore any options they do not recognize Home agents MUST silently ignore any options they do not recognize
and continue processing the message. and continue processing the message.
6.8 ICMP Mobile Prefix Advertisement Message Format 6.8. ICMP Mobile Prefix Advertisement Message Format
A home agent will send a Mobile Prefix Advertisement to a mobile node A home agent will send a Mobile Prefix Advertisement to a mobile node
to distribute prefix information about the home link while the mobile to distribute prefix information about the home link while the mobile
node is traveling away from the home network. This will occur in node is traveling away from the home network. This will occur in
response to a Mobile Prefix Solicitation with an Advertisement, or by response to a Mobile Prefix Solicitation with an Advertisement, or by
an unsolicited Advertisement sent according to the rules in Section an unsolicited Advertisement sent according to the rules in Section
10.6. 10.6.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum | | Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |M|O| Reserved | | Identifier |M|O| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ... | Options ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IP Fields: IP Fields:
Source Address Source Address
The home agent's address as the mobile node would expect to see it The home agent's address as the mobile node would expect to see it
(i.e., same network prefix). (i.e., same network prefix).
Destination Address Destination Address
skipping to change at page 61, line 12 skipping to change at page 60, line 18
ESP header: ESP header:
IPsec headers MUST be supported and SHOULD be used as described in IPsec headers MUST be supported and SHOULD be used as described in
Section 5.4. Section 5.4.
ICMP Fields: ICMP Fields:
Type Type
153 <To Be Assigned by IANA> 147
Code Code
0 0
Checksum Checksum
The ICMP checksum [14]. The ICMP checksum [14].
Identifier Identifier
skipping to change at page 63, line 5 skipping to change at page 61, line 36
Solicitation, the home agent MUST copy the Identifier value from that Solicitation, the home agent MUST copy the Identifier value from that
message into the Identifier field of the Advertisement. message into the Identifier field of the Advertisement.
The home agent MUST NOT send more than one Mobile Prefix The home agent MUST NOT send more than one Mobile Prefix
Advertisement message per second to any mobile node. Advertisement message per second to any mobile node.
The M and O bits MUST be cleared if the Home Agent DHCPv6 support is The M and O bits MUST be cleared if the Home Agent DHCPv6 support is
not provided. If such support is provided then they are set in not provided. If such support is provided then they are set in
concert with the home network's administrative settings. concert with the home network's administrative settings.
7. Modifications to IPv6 Neighbor Discovery 7. Modifications to IPv6 Neighbor Discovery
7.1 Modified Router Advertisement Message Format 7.1. Modified Router Advertisement Message Format
Mobile IPv6 modifies the format of the Router Advertisement message Mobile IPv6 modifies the format of the Router Advertisement message
[12] by the addition of a single flag bit to indicate that the router [12] by the addition of a single flag bit to indicate that the router
sending the Advertisement message is serving as a home agent on this sending the Advertisement message is serving as a home agent on this
link. The format of the Router Advertisement message is as follows: link. The format of the Router Advertisement message is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum | | Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cur Hop Limit |M|O|H| Reserved| Router Lifetime | | Cur Hop Limit |M|O|H| Reserved| Router Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reachable Time | | Reachable Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Retrans Timer | | Retrans Timer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ... | Options ...
+-+-+-+-+-+-+-+-+-+-+-+- +-+-+-+-+-+-+-+-+-+-+-+-
This format represents the following changes over that originally This format represents the following changes over that originally
specified for Neighbor Discovery [12]: specified for Neighbor Discovery [12]:
Home Agent (H) Home Agent (H)
The Home Agent (H) bit is set in a Router Advertisement to The Home Agent (H) bit is set in a Router Advertisement to
indicate that the router sending this Router Advertisement is also indicate that the router sending this Router Advertisement is also
functioning as a Mobile IPv6 home agent on this link. functioning as a Mobile IPv6 home agent on this link.
Reserved Reserved
Reduced from a 6-bit field to a 5-bit field to account for the Reduced from a 6-bit field to a 5-bit field to account for the
addition of the above bit. addition of the above bit.
7.2 Modified Prefix Information Option Format 7.2. Modified Prefix Information Option Format
Mobile IPv6 requires knowledge of a router's global address in Mobile IPv6 requires knowledge of a router's global address in
building a Home Agents List as part of the dynamic home agent address building a Home Agents List as part of the dynamic home agent address
discovery mechanism. discovery mechanism.
However, Neighbor Discovery [12] only advertises a router's However, Neighbor Discovery [12] only advertises a router's link-
link-local address, by requiring this address to be used as the IP local address, by requiring this address to be used as the IP Source
Source Address of each Router Advertisement. Address of each Router Advertisement.
Mobile IPv6 extends Neighbor Discovery to allow a router to advertise Mobile IPv6 extends Neighbor Discovery to allow a router to advertise
its global address, by the addition of a single flag bit in the its global address, by the addition of a single flag bit in the
format of a Prefix Information option for use in Router Advertisement format of a Prefix Information option for use in Router Advertisement
messages. The format of the Prefix Information option is as follows: messages. The format of the Prefix Information option is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Prefix Length |L|A|R|Reserved1| | Type | Length | Prefix Length |L|A|R|Reserved1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Valid Lifetime | | Valid Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preferred Lifetime | | Preferred Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved2 | | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Prefix + + Prefix +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This format represents the following changes over that originally This format represents the following changes over that originally
specified for Neighbor Discovery [12]: specified for Neighbor Discovery [12]:
Router Address (R) Router Address (R)
1-bit router address flag. When set, indicates that the Prefix 1-bit router address flag. When set, indicates that the Prefix
field contains a complete IP address assigned to the sending field contains a complete IP address assigned to the sending
router. The indicated prefix is the first Prefix Length bits of router. The indicated prefix is the first Prefix Length bits of
the Prefix field. The router IP address has the same scope and the Prefix field. The router IP address has the same scope and
skipping to change at page 65, line 23 skipping to change at page 64, line 18
advertisement, if this bit is set in some advertisement sent by the advertisement, if this bit is set in some advertisement sent by the
router. router.
In addition, the following requirement can assist mobile nodes in In addition, the following requirement can assist mobile nodes in
movement detection. Barring changes in the prefixes for the link, movement detection. Barring changes in the prefixes for the link,
routers that send multiple Router Advertisements with the Router routers that send multiple Router Advertisements with the Router
Address (R) bit set in some of the included Prefix Information Address (R) bit set in some of the included Prefix Information
options SHOULD provide at least one option and router address which options SHOULD provide at least one option and router address which
stays the same in all of the Advertisements. stays the same in all of the Advertisements.
7.3 New Advertisement Interval Option Format 7.3. New Advertisement Interval Option Format
Mobile IPv6 defines a new Advertisement Interval option, used in Mobile IPv6 defines a new Advertisement Interval option, used in
Router Advertisement messages to advertise the interval at which the Router Advertisement messages to advertise the interval at which the
sending router sends unsolicited multicast Router Advertisements. sending router sends unsolicited multicast Router Advertisements.
The format of the Advertisement Interval option is as follows: The format of the Advertisement Interval option is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved | | Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertisement Interval | | Advertisement Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type Type
7 7
Length Length
8-bit unsigned integer. The length of the option (including the 8-bit unsigned integer. The length of the option (including the
type and length fields) in units of 8 octets. The value of this type and length fields) is in units of 8 octets. The value of
field MUST be 1. this field MUST be 1.
Reserved Reserved
This field is unused. It MUST be initialized to zero by the This field is unused. It MUST be initialized to zero by the
sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
Advertisement Interval Advertisement Interval
32-bit unsigned integer. The maximum time, in milliseconds, 32-bit unsigned integer. The maximum time, in milliseconds,
between successive unsolicited router Router Advertisement between successive unsolicited Router Advertisement messages sent
messages sent by this router on this network interface. Using the by this router on this network interface. Using the conceptual
conceptual router configuration variables defined by Neighbor router configuration variables defined by Neighbor Discovery [12],
Discovery [12], this field MUST be equal to the value this field MUST be equal to the value MaxRtrAdvInterval, expressed
MaxRtrAdvInterval, expressed in milliseconds. in milliseconds.
Routers MAY include this option in their Router Advertisements. A Routers MAY include this option in their Router Advertisements. A
mobile node receiving a Router Advertisement containing this option mobile node receiving a Router Advertisement containing this option
SHOULD utilize the specified Advertisement Interval for that router SHOULD utilize the specified Advertisement Interval for that router
in its movement detection algorithm, as described in Section 11.5.1. in its movement detection algorithm, as described in Section 11.5.1.
This option MUST be silently ignored for other Neighbor Discovery This option MUST be silently ignored for other Neighbor Discovery
messages. messages.
7.4 New Home Agent Information Option Format 7.4. New Home Agent Information Option Format
Mobile IPv6 defines a new Home Agent Information option, used in Mobile IPv6 defines a new Home Agent Information option, used in
Router Advertisements sent by a home agent to advertise information Router Advertisements sent by a home agent to advertise information
specific to this router's functionality as a home agent. The format specific to this router's functionality as a home agent. The format
of the Home Agent Information option is as follows: of the Home Agent Information option is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved | | Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Agent Preference | Home Agent Lifetime | | Home Agent Preference | Home Agent Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type Type
8 8
Length Length
8-bit unsigned integer. The length of the option (including the 8-bit unsigned integer. The length of the option (including the
type and length fields) in units of 8 octets. The value of this type and length fields) in units of 8 octets. The value of this
field MUST be 1. field MUST be 1.
skipping to change at page 68, line 11 skipping to change at page 67, line 13
from all Advertisements. from all Advertisements.
This option MUST be silently ignored for other Neighbor Discovery This option MUST be silently ignored for other Neighbor Discovery
messages. messages.
If both the Home Agent Preference and Home Agent Lifetime are set to If both the Home Agent Preference and Home Agent Lifetime are set to
their default values specified above, this option SHOULD NOT be their default values specified above, this option SHOULD NOT be
included in the Router Advertisement messages sent by this home included in the Router Advertisement messages sent by this home
agent. agent.
7.5 Changes to Sending Router Advertisements 7.5. Changes to Sending Router Advertisements
The Neighbor Discovery protocol specification [12] limits routers to The Neighbor Discovery protocol specification [12] limits routers to
a minimum interval of 3 seconds between sending unsolicited multicast a minimum interval of 3 seconds between sending unsolicited multicast
Router Advertisement messages from any given network interface Router Advertisement messages from any given network interface
(limited by MinRtrAdvInterval and MaxRtrAdvInterval), stating that: (limited by MinRtrAdvInterval and MaxRtrAdvInterval), stating that:
"Routers generate Router Advertisements frequently enough that "Routers generate Router Advertisements frequently enough that
hosts will learn of their presence within a few minutes, but not hosts will learn of their presence within a few minutes, but not
frequently enough to rely on an absence of advertisements to frequently enough to rely on an absence of advertisements to
detect router failure; a separate Neighbor Unreachability detect router failure; a separate Neighbor Unreachability
skipping to change at page 69, line 4 skipping to change at page 68, line 8
(who may return home and need to hear its Advertisements). (who may return home and need to hear its Advertisements).
Routers supporting mobility SHOULD be able to be configured with a Routers supporting mobility SHOULD be able to be configured with a
smaller MinRtrAdvInterval value and MaxRtrAdvInterval value to allow smaller MinRtrAdvInterval value and MaxRtrAdvInterval value to allow
sending of unsolicited multicast Router Advertisements more often. sending of unsolicited multicast Router Advertisements more often.
The minimum allowed values are: The minimum allowed values are:
o MinRtrAdvInterval 0.03 seconds o MinRtrAdvInterval 0.03 seconds
o MaxRtrAdvInterval 0.07 seconds o MaxRtrAdvInterval 0.07 seconds
In the case where the minimum intervals and delays are used, the mean In the case where the minimum intervals and delays are used, the mean
time between unsolicited multicast router advertisements is 50ms. time between unsolicited multicast router advertisements is 50 ms.
Use of these modified limits MUST be configurable (see also the Use of these modified limits MUST be configurable (see also the
configuration variable MinDelayBetweenRas in Section 13 which may configuration variable MinDelayBetweenRas in Section 13 which may
also have to be modified accordingly). Systems where these values also have to be modified accordingly). Systems where these values
are available MUST NOT default to them, and SHOULD default to values are available MUST NOT default to them, and SHOULD default to values
specified in RFC 2461. Knowledge of the type of network interface specified in RFC 2461. Knowledge of the type of network interface
and operating environment SHOULD be taken into account in configuring and operating environment SHOULD be taken into account in configuring
these limits for each network interface. This is important with some these limits for each network interface. This is important with some
wireless links, where increasing the frequency of multicast beacons wireless links, where increasing the frequency of multicast beacons
can cause considerable overhead. Routers SHOULD adhere to the can cause considerable overhead. Routers SHOULD adhere to the
intervals specified in RFC 2461 [12], if this overhead is likely to intervals specified in RFC 2461 [12], if this overhead is likely to
cause service degradation. cause service degradation.
Additionally, the possible low values of MaxRtrAdvInterval may cause Additionally, the possible low values of MaxRtrAdvInterval may cause
some problems with movement detection in some mobile nodes. To some problems with movement detection in some mobile nodes. To
ensure that this is not a problem, Routers SHOULD add 20ms to any ensure that this is not a problem, Routers SHOULD add 20 ms to any
Advertisement Intervals sent in RAs, which are below 200 ms, in order Advertisement Intervals sent in RAs, which are below 200 ms, in order
to account for scheduling granularities on both the MN and the to account for scheduling granularities on both the MN and the
Router. Router.
Note that multicast Router Advertisements are not always required in Note that multicast Router Advertisements are not always required in
certain wireless networks that have limited bandwidth. Mobility certain wireless networks that have limited bandwidth. Mobility
detection or link changes in such networks may be done at lower detection or link changes in such networks may be done at lower
layers. Router advertisements in such networks SHOULD be sent only layers. Router advertisements in such networks SHOULD be sent only
when solicited. In such networks it SHOULD be possible to disable when solicited. In such networks it SHOULD be possible to disable
unsolicited multicast Router Advertisements on specific interfaces. unsolicited multicast Router Advertisements on specific interfaces.
skipping to change at page 70, line 5 skipping to change at page 69, line 5
returning home, as discussed in Section 11.5.4. returning home, as discussed in Section 11.5.4.
Note that according to RFC 2461 [12], AdvDefaultLifetime is by Note that according to RFC 2461 [12], AdvDefaultLifetime is by
default based on the value of MaxRtrAdvInterval. AdvDefaultLifetime default based on the value of MaxRtrAdvInterval. AdvDefaultLifetime
is used in the Router Lifetime field of Router Advertisements. Given is used in the Router Lifetime field of Router Advertisements. Given
that this field is expressed in seconds, a small MaxRtrAdvInterval that this field is expressed in seconds, a small MaxRtrAdvInterval
value can result in a zero value for this field. To prevent this, value can result in a zero value for this field. To prevent this,
routers SHOULD keep AdvDefaultLifetime in at least one second, even routers SHOULD keep AdvDefaultLifetime in at least one second, even
if the use of MaxRtrAdvInterval would result in a smaller value. if the use of MaxRtrAdvInterval would result in a smaller value.
8. Requirements for Types of IPv6 Nodes 8. Requirements for Types of IPv6 Nodes
Mobile IPv6 places some special requirements on the functions Mobile IPv6 places some special requirements on the functions
provided by different types of IPv6 nodes. This section summarizes provided by different types of IPv6 nodes. This section summarizes
those requirements, identifying the functionality each requirement is those requirements, identifying the functionality each requirement is
intended to support. intended to support.
The requirements are set for the following groups of nodes: The requirements are set for the following groups of nodes:
o All IPv6 nodes. o All IPv6 nodes.
skipping to change at page 70, line 29 skipping to change at page 69, line 29
o All Mobile IPv6 home agents. o All Mobile IPv6 home agents.
o All Mobile IPv6 mobile nodes. o All Mobile IPv6 mobile nodes.
It is outside the scope of this specification to specify which of It is outside the scope of this specification to specify which of
these groups are mandatory in IPv6. We only describe what is these groups are mandatory in IPv6. We only describe what is
mandatory for a node that supports, for instance, route optimization. mandatory for a node that supports, for instance, route optimization.
Other specifications are expected to define the extent of IPv6. Other specifications are expected to define the extent of IPv6.
8.1 All IPv6 Nodes 8.1. All IPv6 Nodes
Any IPv6 node may at any time be a correspondent node of a mobile Any IPv6 node may at any time be a correspondent node of a mobile
node, either sending a packet to a mobile node or receiving a packet node, either sending a packet to a mobile node or receiving a packet
from a mobile node. There are no Mobile IPv6 specific MUST from a mobile node. There are no Mobile IPv6 specific MUST
requirements for such nodes, and basic IPv6 techniques are requirements for such nodes, and basic IPv6 techniques are
sufficient. If a mobile node attempts to set up route optimization sufficient. If a mobile node attempts to set up route optimization
with a node with only basic IPv6 support, an ICMP error will signal with a node with only basic IPv6 support, an ICMP error will signal
that the node does not support such optimizations (Section 11.3.5), that the node does not support such optimizations (Section 11.3.5),
and communications will flow through the home agent . and communications will flow through the home agent.
An IPv6 node MUST NOT support the Home Address destination option, An IPv6 node MUST NOT support the Home Address destination option,
type 2 routing header, or the Mobility Header unless it fully type 2 routing header, or the Mobility Header unless it fully
supports the requirements listed in the next sections for either supports the requirements listed in the next sections for either
route optimization, mobile node, or home agent functionality. route optimization, mobile node, or home agent functionality.
8.2 IPv6 Nodes with Support for Route Optimization 8.2. IPv6 Nodes with Support for Route Optimization
Nodes that implement route optimization are a subset of all IPv6 Nodes that implement route optimization are a subset of all IPv6
nodes on the Internet. The ability of a correspondent node to nodes on the Internet. The ability of a correspondent node to
participate in route optimization is essential for the efficient participate in route optimization is essential for the efficient
operation of the IPv6 Internet, for the following reasons: operation of the IPv6 Internet, for the following reasons:
o Avoidance of congestion in the home network, and enabling the use o Avoidance of congestion in the home network, and enabling the use
of lower-performance home agent equipment even for supporting of lower-performance home agent equipment even for supporting
thousands of mobile nodes. thousands of mobile nodes.
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additional state for the peers, some additional messaging, and up to additional state for the peers, some additional messaging, and up to
1.5 roundtrip delays before it can be turned on. However, it is 1.5 roundtrip delays before it can be turned on. However, it is
believed that the benefits far outweigh the costs in most cases. believed that the benefits far outweigh the costs in most cases.
Section 11.3.1 discusses how mobile nodes may avoid route Section 11.3.1 discusses how mobile nodes may avoid route
optimization for some of the remaining cases, such as very short-term optimization for some of the remaining cases, such as very short-term
communications. communications.
The following requirements apply to all correspondent nodes that The following requirements apply to all correspondent nodes that
support route optimization: support route optimization:
o The node MUST be able validate a Home Address option using an o The node MUST be able to validate a Home Address option using an
existing Binding Cache entry, as described in Section 9.3.1. existing Binding Cache entry, as described in Section 9.3.1.
o The node MUST be able to insert a type 2 routing header into o The node MUST be able to insert a type 2 routing header into
packets to be sent to a mobile node, as described in Section packets to be sent to a mobile node, as described in Section
9.3.2. 9.3.2.
o Unless the correspondent node is also acting as a mobile node, it o Unless the correspondent node is also acting as a mobile node, it
MUST ignore type 2 routing headers and silently discard all MUST ignore type 2 routing headers and silently discard all
packets that it has received with such headers. packets that it has received with such headers.
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o The node MUST be able to return a Binding Acknowledgement (Section o The node MUST be able to return a Binding Acknowledgement (Section
9.5.4). 9.5.4).
o The node MUST be able to maintain a Binding Cache of the bindings o The node MUST be able to maintain a Binding Cache of the bindings
received in accepted Binding Updates, as described in Section 9.1 received in accepted Binding Updates, as described in Section 9.1
and Section 9.6. and Section 9.6.
o The node SHOULD allow route optimization to be administratively o The node SHOULD allow route optimization to be administratively
enabled or disabled. The default SHOULD be enabled. enabled or disabled. The default SHOULD be enabled.
8.3 All IPv6 Routers 8.3. All IPv6 Routers
All IPv6 routers, even those not serving as a home agent for Mobile All IPv6 routers, even those not serving as a home agent for Mobile
IPv6, have an effect on how well mobile nodes can communicate: IPv6, have an effect on how well mobile nodes can communicate:
o Every IPv6 router SHOULD be able to send an Advertisement Interval o Every IPv6 router SHOULD be able to send an Advertisement Interval
option (Section 7.3) in each of its Router Advertisements [12], to option (Section 7.3) in each of its Router Advertisements [12], to
aid movement detection by mobile nodes (as in Section 11.5.1). aid movement detection by mobile nodes (as in Section 11.5.1).
The use of this option in Router Advertisements SHOULD be The use of this option in Router Advertisements SHOULD be
configurable. configurable.
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o Each router SHOULD include at least one prefix with the Router o Each router SHOULD include at least one prefix with the Router
Address (R) bit set and with its full IP address in its Router Address (R) bit set and with its full IP address in its Router
Advertisements (as described in Section 7.2). Advertisements (as described in Section 7.2).
o Routers supporting filtering packets with routing headers SHOULD o Routers supporting filtering packets with routing headers SHOULD
support different rules for type 0 and type 2 routing headers (see support different rules for type 0 and type 2 routing headers (see
Section 6.4) so that filtering of source routed packets (type 0) Section 6.4) so that filtering of source routed packets (type 0)
will not necessarily limit Mobile IPv6 traffic which is delivered will not necessarily limit Mobile IPv6 traffic which is delivered
via type 2 routing headers. via type 2 routing headers.
8.4 IPv6 Home Agents 8.4. IPv6 Home Agents
In order for a mobile node to operate correctly while away from home, In order for a mobile node to operate correctly while away from home,
at least one IPv6 router on the mobile node's home link must function at least one IPv6 router on the mobile node's home link must function
as a home agent for the mobile node. The following additional as a home agent for the mobile node. The following additional
requirements apply to all IPv6 routers that serve as a home agent: requirements apply to all IPv6 routers that serve as a home agent:
o Every home agent MUST be able to maintain an entry in its Binding o Every home agent MUST be able to maintain an entry in its Binding
Cache for each mobile node for which it is serving as the home Cache for each mobile node for which it is serving as the home
agent (Section 10.1 and Section 10.3.1). agent (Section 10.1 and Section 10.3.1).
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o Every home agent SHOULD support the multicast group membership o Every home agent SHOULD support the multicast group membership
control protocols as described in Section 10.4.3. If this support control protocols as described in Section 10.4.3. If this support
is provided, the home agent MUST be capable of using it to is provided, the home agent MUST be capable of using it to
determine which multicast data packets to forward via the tunnel determine which multicast data packets to forward via the tunnel
to the mobile node. to the mobile node.
o Home agents MAY support stateful address autoconfiguration for o Home agents MAY support stateful address autoconfiguration for
mobile nodes as described in Section 10.4.4. mobile nodes as described in Section 10.4.4.
8.5 IPv6 Mobile Nodes 8.5. IPv6 Mobile Nodes
Finally, the following requirements apply to all IPv6 nodes capable Finally, the following requirements apply to all IPv6 nodes capable
of functioning as mobile nodes: of functioning as mobile nodes:
o The node MUST maintain a Binding Update List (Section 11.1). o The node MUST maintain a Binding Update List (Section 11.1).
o The node MUST support sending packets containing a Home Address o The node MUST support sending packets containing a Home Address
option (Section 11.3.1), and follow the required IPsec interaction option (Section 11.3.1), and follow the required IPsec interaction
(Section 11.3.2). (Section 11.3.2).
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o The node MAY support the multicast address listener part of a o The node MAY support the multicast address listener part of a
multicast group membership protocol as described in Section multicast group membership protocol as described in Section
11.3.4. If this support is provided, the mobile node MUST be able 11.3.4. If this support is provided, the mobile node MUST be able
to receive tunneled multicast packets from the home agent. to receive tunneled multicast packets from the home agent.
o The node MAY support stateful address autoconfiguration mechanisms o The node MAY support stateful address autoconfiguration mechanisms
such as DHCPv6 [29] on the interface represented by the tunnel to such as DHCPv6 [29] on the interface represented by the tunnel to
the home agent. the home agent.
9. Correspondent Node Operation 9. Correspondent Node Operation
9.1 Conceptual Data Structures 9.1. Conceptual Data Structures
IPv6 nodes with route optimization support maintain a Binding Cache IPv6 nodes with route optimization support maintain a Binding Cache
of bindings for other nodes. A separate Binding Cache SHOULD be of bindings for other nodes. A separate Binding Cache SHOULD be
maintained by each IPv6 node for each of its unicast routable maintained by each IPv6 node for each of its unicast routable
addresses. The Binding Cache MAY be implemented in any manner addresses. The Binding Cache MAY be implemented in any manner
consistent with the external behavior described in this document, for consistent with the external behavior described in this document, for
example by being combined with the node's Destination Cache as example by being combined with the node's Destination Cache as
maintained by Neighbor Discovery [12]. When sending a packet, the maintained by Neighbor Discovery [12]. When sending a packet, the
Binding Cache is searched before the Neighbor Discovery conceptual Binding Cache is searched before the Neighbor Discovery conceptual
Destination Cache [12]. Destination Cache [12].
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this entry nears expiration. this entry nears expiration.
Binding Cache entries not marked as home registrations MAY be Binding Cache entries not marked as home registrations MAY be
replaced at any time by any reasonable local cache replacement policy replaced at any time by any reasonable local cache replacement policy
but SHOULD NOT be unnecessarily deleted. The Binding Cache for any but SHOULD NOT be unnecessarily deleted. The Binding Cache for any
one of a node's IPv6 addresses may contain at most one entry for each one of a node's IPv6 addresses may contain at most one entry for each
mobile node home address. The contents of a node's Binding Cache mobile node home address. The contents of a node's Binding Cache
MUST NOT be changed in response to a Home Address option in a MUST NOT be changed in response to a Home Address option in a
received packet. received packet.
9.2 Processing Mobility Headers 9.2. Processing Mobility Headers
Mobility Header processing MUST observe the following rules: Mobility Header processing MUST observe the following rules:
o The checksum must be verified as per Section 6.1. Otherwise, the o The checksum must be verified as per Section 6.1. Otherwise, the
node MUST silently discard the message. node MUST silently discard the message.
o The MH Type field MUST have a known value (Section 6.1.1). o The MH Type field MUST have a known value (Section 6.1.1).
Otherwise, the node MUST discard the message and issue a Binding Otherwise, the node MUST discard the message and issue a Binding
Error message as described in Section 9.3.3, with Status field set Error message as described in Section 9.3.3, with Status field set
to 2 (unrecognized MH Type value). to 2 (unrecognized MH Type value).
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field in the ICMP message SHOULD point at the Payload Proto field. field in the ICMP message SHOULD point at the Payload Proto field.
o The Header Len field in the Mobility Header MUST NOT be less than o The Header Len field in the Mobility Header MUST NOT be less than
the length specified for this particular type of message in the length specified for this particular type of message in
Section 6.1. Otherwise, the node MUST discard the message and Section 6.1. Otherwise, the node MUST discard the message and
SHOULD send ICMP Parameter Problem, Code 0, directly to the Source SHOULD send ICMP Parameter Problem, Code 0, directly to the Source
Address of the packet as specified in RFC 2463 [14]. (The Binding Address of the packet as specified in RFC 2463 [14]. (The Binding
Cache information is again not used.) The Pointer field in the Cache information is again not used.) The Pointer field in the
ICMP message SHOULD point at the Header Len field. ICMP message SHOULD point at the Header Len field.
Subsequent checks depend on the particular Mobility Header. Subsequent checks depend on the particular Mobility Header.
9.3 Packet Processing 9.3. Packet Processing
This section describes how the correspondent node sends packets to This section describes how the correspondent node sends packets to
the mobile node, and receives packets from it. the mobile node, and receives packets from it.
9.3.1 Receiving Packets with Home Address Option 9.3.1. Receiving Packets with Home Address Option
Packets containing a Home Address option MUST be dropped if the given Packets containing a Home Address option MUST be dropped if the given
home address is not a unicast routable address. home address is not a unicast routable address.
Mobile nodes can include a Home Address destination option in a Mobile nodes can include a Home Address destination option in a
packet if they believe the correspondent node has a Binding Cache packet if they believe the correspondent node has a Binding Cache
entry for the home address of a mobile node. Packets containing a entry for the home address of a mobile node. Packets containing a
Home Address option MUST be dropped if there is no corresponding Home Address option MUST be dropped if there is no corresponding
Binding Cache entry. A corresponding Binding Cache entry MUST have Binding Cache entry. A corresponding Binding Cache entry MUST have
the same home address as appears in the Home Address destination the same home address as appears in the Home Address destination
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Address field there. After all IPv6 options have been processed, it Address field there. After all IPv6 options have been processed, it
MUST be possible for upper layers to process the packet without the MUST be possible for upper layers to process the packet without the
knowledge that it came originally from a care-of address or that a knowledge that it came originally from a care-of address or that a
Home Address option was used. Home Address option was used.
The use of IPsec Authentication Header (AH) for the Home Address The use of IPsec Authentication Header (AH) for the Home Address
option is not required, except that if the IPv6 header of a packet is option is not required, except that if the IPv6 header of a packet is
covered by AH, then the authentication MUST also cover the Home covered by AH, then the authentication MUST also cover the Home
Address option; this coverage is achieved automatically by the Address option; this coverage is achieved automatically by the
definition of the Option Type code for the Home Address option, since definition of the Option Type code for the Home Address option, since
it indicates that the data within the option cannot change en-route it indicates that the data within the option cannot change en route
to the packet's final destination, and thus the option is included in to the packet's final destination, and thus the option is included in
the AH computation. By requiring that any authentication of the IPv6 the AH computation. By requiring that any authentication of the IPv6
header also cover the Home Address option, the security of the Source header also cover the Home Address option, the security of the Source
Address field in the IPv6 header is not compromised by the presence Address field in the IPv6 header is not compromised by the presence
of a Home Address option. of a Home Address option.
When attempting to verify AH authentication data in a packet that When attempting to verify AH authentication data in a packet that
contains a Home Address option, the receiving node MUST calculate the contains a Home Address option, the receiving node MUST calculate the
AH authentication data as if the following were true: The Home AH authentication data as if the following were true: The Home
Address option contains the care-of address, and the source IPv6 Address option contains the care-of address, and the source IPv6
address field of the IPv6 header contains the home address. This address field of the IPv6 header contains the home address. This
conforms with the calculation specified in Section 11.3.2. conforms with the calculation specified in Section 11.3.2.
9.3.2 Sending Packets to a Mobile Node 9.3.2. Sending Packets to a Mobile Node
Before sending any packet, the sending node SHOULD examine its Before sending any packet, the sending node SHOULD examine its
Binding Cache for an entry for the destination address to which the Binding Cache for an entry for the destination address to which the
packet is being sent. If the sending node has a Binding Cache entry packet is being sent. If the sending node has a Binding Cache entry
for this address, the sending node SHOULD use a type 2 routing header for this address, the sending node SHOULD use a type 2 routing header
to route the packet to this mobile node (the destination node) by way to route the packet to this mobile node (the destination node) by way
of its care-of address. However, the mobile node MUST not do this in of its care-of address. However, the sending node MUST not do this
the following cases: in the following cases:
o When sending an IPv6 Neighbor Discovery [12] packet. o When sending an IPv6 Neighbor Discovery [12] packet.
o Where otherwise noted in Section 6.1. o Where otherwise noted in Section 6.1.
When calculating authentication data in a packet that contains a type When calculating authentication data in a packet that contains a type
2 routing header, the correspondent node MUST calculate the AH 2 routing header, the correspondent node MUST calculate the AH
authentication data as if the following were true: The routing header authentication data as if the following were true: The routing header
contains the care-of address, the destination IPv6 address field of contains the care-of address, the destination IPv6 address field of
the IPv6 header contains the home address, and the Segments Left the IPv6 header contains the home address, and the Segments Left
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If, instead, the sending node has no Binding Cache entry for the If, instead, the sending node has no Binding Cache entry for the
destination address to which the packet is being sent, the sending destination address to which the packet is being sent, the sending
node simply sends the packet normally, with no routing header. If node simply sends the packet normally, with no routing header. If
the destination node is not a mobile node (or is a mobile node that the destination node is not a mobile node (or is a mobile node that
is currently at home), the packet will be delivered directly to this is currently at home), the packet will be delivered directly to this
node and processed normally by it. If, however, the destination node node and processed normally by it. If, however, the destination node
is a mobile node that is currently away from home, the packet will be is a mobile node that is currently away from home, the packet will be
intercepted by the mobile node's home agent and tunneled to the intercepted by the mobile node's home agent and tunneled to the
mobile node's current primary care-of address. mobile node's current primary care-of address.
9.3.3 Sending Binding Error Messages 9.3.3. Sending Binding Error Messages
Section 9.2 and Section 9.3.1 describe error conditions that lead to Section 9.2 and Section 9.3.1 describe error conditions that lead to
a need to send a Binding Error message. a need to send a Binding Error message.
A Binding Error message is sent directly to the address that appeared A Binding Error message is sent directly to the address that appeared
in the IPv6 Source Address field of the offending packet. If the in the IPv6 Source Address field of the offending packet. If the
Source Address field does not contain a unicast address, the Binding Source Address field does not contain a unicast address, the Binding
Error message MUST NOT be sent. Error message MUST NOT be sent.
The Home Address field in the Binding Error message MUST be copied The Home Address field in the Binding Error message MUST be copied
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the offending packet, or set to the unspecified address if no such the offending packet, or set to the unspecified address if no such
option appeared in the packet. option appeared in the packet.
Note that the IPv6 Source Address and Home Address field values Note that the IPv6 Source Address and Home Address field values
discussed above are the values from the wire, i.e., before any discussed above are the values from the wire, i.e., before any
modifications possibly performed as specified in Section 9.3.1. modifications possibly performed as specified in Section 9.3.1.
Binding Error messages SHOULD be subject to rate limiting in the same Binding Error messages SHOULD be subject to rate limiting in the same
manner as is done for ICMPv6 messages [14]. manner as is done for ICMPv6 messages [14].
9.3.4 Receiving ICMP Error Messages 9.3.4. Receiving ICMP Error Messages
When the correspondent node has a Binding Cache entry for a mobile When the correspondent node has a Binding Cache entry for a mobile
node, all traffic destined to the mobile node goes directly to the node, all traffic destined to the mobile node goes directly to the
current care-of address of the mobile node using a routing header. current care-of address of the mobile node using a routing header.
Any ICMP error message caused by packets on their way to the care-of Any ICMP error message caused by packets on their way to the care-of
address will be returned in the normal manner to the correspondent address will be returned in the normal manner to the correspondent
node. node.
On the other hand, if the correspondent node has no Binding Cache On the other hand, if the correspondent node has no Binding Cache
entry for the mobile node, the packet will be routed through the entry for the mobile node, the packet will be routed through the
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to the correspondent node. If the correspondent node receives to the correspondent node. If the correspondent node receives
persistent ICMP Destination Unreachable messages after sending persistent ICMP Destination Unreachable messages after sending
packets to a mobile node based on an entry in its Binding Cache, the packets to a mobile node based on an entry in its Binding Cache, the
correspondent node SHOULD delete this Binding Cache entry. Note that correspondent node SHOULD delete this Binding Cache entry. Note that
if the mobile node continues to send packets with the Home Address if the mobile node continues to send packets with the Home Address
destination option to this correspondent node, they will be dropped destination option to this correspondent node, they will be dropped
due to the lack of a binding. For this reason it is important that due to the lack of a binding. For this reason it is important that
only persistent ICMP messages lead to the deletion of the Binding only persistent ICMP messages lead to the deletion of the Binding
Cache entry. Cache entry.
9.4 Return Routability Procedure 9.4. Return Routability Procedure
This subsection specifies actions taken by a correspondent node This subsection specifies actions taken by a correspondent node
during the return routability procedure. during the return routability procedure.
9.4.1 Receiving Home Test Init Messages 9.4.1. Receiving Home Test Init Messages
Upon receiving a Home Test Init message, the correspondent node Upon receiving a Home Test Init message, the correspondent node
verifies the following: verifies the following:
o The packet MUST NOT include a Home Address destination option. o The packet MUST NOT include a Home Address destination option.
Any packet carrying a Home Test Init message which fails to satisfy Any packet carrying a Home Test Init message which fails to satisfy
all of these tests MUST be silently ignored. all of these tests MUST be silently ignored.
Otherwise, in preparation for sending the corresponding Home Test Otherwise, in preparation for sending the corresponding Home Test
Message, the correspondent node checks that it has the necessary Message, the correspondent node checks that it has the necessary
material to engage in a return routability procedure, as specified in material to engage in a return routability procedure, as specified in
Section 5.2. The correspondent node MUST have a secret Kcn and a Section 5.2. The correspondent node MUST have a secret Kcn and a
nonce. If it does not have this material yet, it MUST produce it nonce. If it does not have this material yet, it MUST produce it
before continuing with the return routability procedure. before continuing with the return routability procedure.
Section 9.4.3 specifies further processing. Section 9.4.3 specifies further processing.
9.4.2 Receiving Care-of Test Init Messages 9.4.2. Receiving Care-of Test Init Messages
Upon receiving a Care-of Test Init message, the correspondent node Upon receiving a Care-of Test Init message, the correspondent node
verifies the following: verifies the following:
o The packet MUST NOT include a Home Address destination option. o The packet MUST NOT include a Home Address destination option.
Any packet carrying a Care-of Test Init message which fails to Any packet carrying a Care-of Test Init message which fails to
satisfy all of these tests MUST be silently ignored. satisfy all of these tests MUST be silently ignored.
Otherwise, in preparation for sending the corresponding Care-of Test Otherwise, in preparation for sending the corresponding Care-of Test
Message, the correspondent node checks that it has the necessary Message, the correspondent node checks that it has the necessary
material to engage in a return routability procedure in the manner material to engage in a return routability procedure in the manner
described in Section 9.4.1. described in Section 9.4.1.
Section 9.4.4 specifies further processing. Section 9.4.4 specifies further processing.
9.4.3 Sending Home Test Messages 9.4.3. Sending Home Test Messages
The correspondent node creates a home keygen token and uses the The correspondent node creates a home keygen token and uses the
current nonce index as the Home Nonce Index. It then creates a Home current nonce index as the Home Nonce Index. It then creates a Home
Test message (Section 6.1.5) and sends it to the mobile node at the Test message (Section 6.1.5) and sends it to the mobile node at the
latter's home address. latter's home address.
9.4.4 Sending Care-of Test Messages 9.4.4. Sending Care-of Test Messages
The correspondent node creates a care-of nonce and uses the current The correspondent node creates a care-of keygen token and uses the
nonce index as the Care-of Nonce Index. It then creates a Care-of current nonce index as the Care-of Nonce Index. It then creates a
Test message (Section 6.1.6) and sends it to the mobile node at the Care-of Test message (Section 6.1.6) and sends it to the mobile node
latter's care-of address. at the latter's care-of address.
9.5 Processing Bindings 9.5. Processing Bindings
This section explains how the correspondent node processes messages This section explains how the correspondent node processes messages
related to bindings. These messages are: related to bindings. These messages are:
o Binding Update o Binding Update
o Binding Refresh Request o Binding Refresh Request
o Binding Acknowledgement o Binding Acknowledgement
o Binding Error o Binding Error
9.5.1 Receiving Binding Updates 9.5.1. Receiving Binding Updates
Before accepting a Binding Update, the receiving node MUST validate Before accepting a Binding Update, the receiving node MUST validate
the Binding Update according to the following tests: the Binding Update according to the following tests:
o The packet MUST contain a unicast routable home address, either in o The packet MUST contain a unicast routable home address, either in
the Home Address option or in the Source Address, if the Home the Home Address option or in the Source Address, if the Home
Address option is not present. Address option is not present.
o The Sequence Number field in the Binding Update is greater than o The Sequence Number field in the Binding Update is greater than
the Sequence Number received in the previous valid Binding Update the Sequence Number received in the previous valid Binding Update
for this home address, if any. for this home address, if any.
If the receiving node has no Binding Cache entry for the indicated If the receiving node has no Binding Cache entry for the indicated
home address, it MUST accept any Sequence Number value in a home address, it MUST accept any Sequence Number value in a received
received Binding Update from this mobile node. Binding Update from this mobile node.
This Sequence Number comparison MUST be performed modulo 2**16, This Sequence Number comparison MUST be performed modulo 2**16, i.e.,
i.e., the number is a free running counter represented modulo the number is a free running counter represented modulo 65536. A
65536. A Sequence Number in a received Binding Update is Sequence Number in a received Binding Update is considered less than
considered less than or equal to the last received number if its or equal to the last received number if its value lies in the range
value lies in the range of the last received number and the of the last received number and the preceding 32768 values,
preceding 32768 values, inclusive. For example, if the last inclusive. For example, if the last received sequence number was 15,
received sequence number was 15, then messages with sequence then messages with sequence numbers 0 through 15, as well as 32783
numbers 0 through 15, as well as 32783 through 65535, would be through 65535, would be considered less than or equal.
considered less than or equal.
When the Home Registration (H) bit is not set, the following are also When the Home Registration (H) bit is not set, the following are also
required: required:
o A Nonce Indices mobility option MUST be present, and the Home and o A Nonce Indices mobility option MUST be present, and the Home and
Care-of Nonce Index values in this option MUST be recent enough to Care-of Nonce Index values in this option MUST be recent enough to
be recognized by the correspondent node. (Care-of Nonce Index be recognized by the correspondent node. (Care-of Nonce Index
values are not inspected for requests to delete a binding.) values are not inspected for requests to delete a binding.)
o The correspondent node MUST re-generate the home keygen token and o The correspondent node MUST re-generate the home keygen token and
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(H) bit in the Binding Update, then the receiving node MUST send back (H) bit in the Binding Update, then the receiving node MUST send back
a Binding Acknowledgement with status code 139 (registration type a Binding Acknowledgement with status code 139 (registration type
change disallowed). The home registration flag stored in the Binding change disallowed). The home registration flag stored in the Binding
Cache entry MUST NOT be changed. Cache entry MUST NOT be changed.
If the receiving node no longer recognizes the Home Nonce Index If the receiving node no longer recognizes the Home Nonce Index
value, Care-of Nonce Index value, or both values from the Binding value, Care-of Nonce Index value, or both values from the Binding
Update, then the receiving node MUST send back a Binding Update, then the receiving node MUST send back a Binding
Acknowledgement with status code 136, 137, or 138, respectively. Acknowledgement with status code 136, 137, or 138, respectively.
For packets carrying Binding Updates that fail to satisfy all of Packets carrying Binding Updates that fail to satisfy all of these
these tests for any reason other than insufficiency of the Sequence tests for any reason other than insufficiency of the Sequence Number,
Number, registration type change, or expired nonce index values, they registration type change, or expired nonce index values, MUST be
MUST be silently discarded. silently discarded.
If the Binding Update is valid according to the tests above, then the If the Binding Update is valid according to the tests above, then the
Binding Update is processed further as follows: Binding Update is processed further as follows:
o The Sequence Number value received from a mobile node in a Binding o The Sequence Number value received from a mobile node in a Binding
Update is stored by the receiving node in its Binding Cache entry Update is stored by the receiving node in its Binding Cache entry
for the given home address. for the given home address.
o If the Lifetime specified in the Binding Update is nonzero and the o If the Lifetime specified in the Binding Update is nonzero and the
specified care-of address is not equal to the home address for the specified care-of address is not equal to the home address for the
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packet's IPv6 header. packet's IPv6 header.
The home address for the binding MUST be determined as follows: The home address for the binding MUST be determined as follows:
o If the Home Address destination option is present, the home o If the Home Address destination option is present, the home
address is the address in that option. address is the address in that option.
o Otherwise, the home address is the Source Address field in the o Otherwise, the home address is the Source Address field in the
packet's IPv6 header. packet's IPv6 header.
9.5.2 Requests to Cache a Binding 9.5.2. Requests to Cache a Binding
This section describes the processing of a valid Binding Update that This section describes the processing of a valid Binding Update that
requests a node to cache a binding, for which the Home Registration requests a node to cache a binding, for which the Home Registration
(H) bit is not set in the Binding Update. (H) bit is not set in the Binding Update.
In this case, the receiving node SHOULD create a new entry in its In this case, the receiving node SHOULD create a new entry in its
Binding Cache for this home address, or update its existing Binding Binding Cache for this home address, or update its existing Binding
Cache entry for this home address, if such an entry already exists. Cache entry for this home address, if such an entry already exists.
The lifetime for the Binding Cache entry is initialized from the The lifetime for the Binding Cache entry is initialized from the
Lifetime field specified in the Binding Update, although this Lifetime field specified in the Binding Update, although this
lifetime MAY be reduced by the node caching the binding; the lifetime lifetime MAY be reduced by the node caching the binding; the lifetime
for the Binding Cache entry MUST NOT be greater than the Lifetime for the Binding Cache entry MUST NOT be greater than the Lifetime
value specified in the Binding Update. Any Binding Cache entry MUST value specified in the Binding Update. Any Binding Cache entry MUST
be deleted after the expiration of its lifetime. be deleted after the expiration of its lifetime.
Note that if the mobile node did not request a Binding Note that if the mobile node did not request a Binding
Acknowledgement, it is not aware of the selected shorter lifetime. Acknowledgement, then it is not aware of the selected shorter
The mobile node may thus use route optimization and send packets with lifetime. The mobile node may thus use route optimization and send
the Home Address destination option. As discussed in Section 9.3.1, packets with the Home Address destination option. As discussed in
such packets will be dropped if there is no binding. This situation Section 9.3.1, such packets will be dropped if there is no binding.
is recoverable, but can cause temporary packet loss. This situation is recoverable, but can cause temporary packet loss.
The correspondent node MAY refuse to accept a new Binding Cache The correspondent node MAY refuse to accept a new Binding Cache entry
entry, if it does not have sufficient resources. A new entry MAY if it does not have sufficient resources. A new entry MAY also be
also be refused if the correspondent node believes its resources are refused if the correspondent node believes its resources are utilized
utilized more efficiently in some other purpose, such as serving more efficiently in some other purpose, such as serving another
another mobile node with higher amount of traffic. In both cases the mobile node with higher amount of traffic. In both cases the
correspondent node SHOULD return a Binding Acknowledgement with correspondent node SHOULD return a Binding Acknowledgement with
status value 130. status value 130.
9.5.3 Requests to Delete a Binding 9.5.3 Requests to Delete a Binding
This section describes the processing of a valid Binding Update that This section describes the processing of a valid Binding Update that
requests a node to delete a binding, when the Home Registration (H) requests a node to delete a binding when the Home Registration (H)
bit is not set in the Binding Update. bit is not set in the Binding Update.
Any existing binding for the given home address MUST be deleted. A Any existing binding for the given home address MUST be deleted. A
Binding Cache entry for the home address MUST NOT be created in Binding Cache entry for the home address MUST NOT be created in
response to receiving the Binding Update. response to receiving the Binding Update.
If the Binding Cache entry was created by use of return routability If the Binding Cache entry was created by use of return routability
nonces, the correspondent node MUST ensure that the same nonces are nonces, the correspondent node MUST ensure that the same nonces are
not used again with the particular home and care-of address. If both not used again with the particular home and care-of address. If both
nonces are still valid, the correspondent node has to remember the nonces are still valid, the correspondent node has to remember the
particular combination of nonce indexes, addresses, and sequence particular combination of nonce indexes, addresses, and sequence
number as illegal, until at least one of the nonces has become too number as illegal until at least one of the nonces has become too
old. old.
9.5.4 Sending Binding Acknowledgements 9.5.4. Sending Binding Acknowledgements
A Binding Acknowledgement may be sent to indicate receipt of a A Binding Acknowledgement may be sent to indicate receipt of a
Binding Update as follows: Binding Update as follows:
o If the Binding Update was discarded as described in Section 9.2 or o If the Binding Update was discarded as described in Section 9.2 or
Section 9.5.1, a Binding Acknowledgement MUST NOT be sent. Section 9.5.1, a Binding Acknowledgement MUST NOT be sent.
Otherwise the treatment depends on the below rules. Otherwise the treatment depends on the following rules.
o If the Acknowledge (A) bit set is set in the Binding Update, a o If the Acknowledge (A) bit set is set in the Binding Update, a
Binding Acknowledgement MUST be sent. Otherwise, the treatment Binding Acknowledgement MUST be sent. Otherwise, the treatment
depends on the below rule. depends on the below rule.
o If the node rejects the Binding Update due to an expired nonce o If the node rejects the Binding Update due to an expired nonce
index, sequence number being out of window (Section 9.5.1), or index, sequence number being out of window (Section 9.5.1), or
insufficiency of resources (Section 9.5.2), a Binding insufficiency of resources (Section 9.5.2), a Binding
Acknowledgement MUST be sent. If the node accepts the Binding Acknowledgement MUST be sent. If the node accepts the Binding
Update, the Binding Acknowledgement SHOULD NOT be sent. Update, the Binding Acknowledgement SHOULD NOT be sent.
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If the Status field in the Binding Acknowledgement contains the value If the Status field in the Binding Acknowledgement contains the value
136 (expired home nonce index), 137 (expired care-of nonce index), or 136 (expired home nonce index), 137 (expired care-of nonce index), or
138 (expired nonces) then the message MUST NOT include the Binding 138 (expired nonces) then the message MUST NOT include the Binding
Authorization Data mobility option. Otherwise, the Binding Authorization Data mobility option. Otherwise, the Binding
Authorization Data mobility option MUST be included, and MUST meet Authorization Data mobility option MUST be included, and MUST meet
the specific authentication requirements for Binding Acknowledgements the specific authentication requirements for Binding Acknowledgements
as defined in Section 5.2. as defined in Section 5.2.
If the Source Address field of the IPv6 header that carried the If the Source Address field of the IPv6 header that carried the
Binding Update does not contain a unicast address, the Binding Binding Update does not contain a unicast address, the Binding
Acknowledgement MUST NOT be sent, and the Binding Update packet MUST Acknowledgement MUST NOT be sent and the Binding Update packet MUST
be silently discarded. Otherwise, the acknowledgement MUST be sent be silently discarded. Otherwise, the acknowledgement MUST be sent
to the Source Address. Unlike the treatment of regular packets, this to the Source Address. Unlike the treatment of regular packets, this
addressing procedure does not use information from the Binding Cache. addressing procedure does not use information from the Binding Cache.
However, a routing header is needed in some cases. If the Source However, a routing header is needed in some cases. If the Source
Address is the home address of the mobile node, i.e., the Binding Address is the home address of the mobile node, i.e., the Binding
Update did not contain a Home Address destination option, then the Update did not contain a Home Address destination option, then the
Binding Acknowledgement MUST be sent to that address, and the routing Binding Acknowledgement MUST be sent to that address and the routing
header MUST NOT be used. Otherwise, the Binding Acknowledgement MUST header MUST NOT be used. Otherwise, the Binding Acknowledgement MUST
be sent using a type 2 routing header which contains the mobile be sent using a type 2 routing header which contains the mobile
node's home address. node's home address.
9.5.5 Sending Binding Refresh Requests 9.5.5. Sending Binding Refresh Requests
If a Binding Cache entry being deleted is still in active use in If a Binding Cache entry being deleted is still in active use when
sending packets to a mobile node, the next packet sent to the mobile sending packets to a mobile node, then the next packet sent to the
node will be routed normally to the mobile node's home link. mobile node will be routed normally to the mobile node's home link.
Communication with the mobile node continues, but the tunneling from Communication with the mobile node continues, but the tunneling from
the home network creates additional overhead and latency in the home network creates additional overhead and latency in
delivering packets to the mobile node. delivering packets to the mobile node.
If the sender knows that the Binding Cache entry is still in active If the sender knows that the Binding Cache entry is still in active
use, it MAY send a Binding Refresh Request message to the mobile node use, it MAY send a Binding Refresh Request message to the mobile node
in an attempt to avoid this overhead and latency due to deleting and in an attempt to avoid this overhead and latency due to deleting and
recreating the Binding Cache entry. recreating the Binding Cache entry. This message is always sent to
the home address of the mobile node.
The correspondent node MAY retransmit Binding Refresh Request The correspondent node MAY retransmit Binding Refresh Request
messages provided that rate limitation is applied. The correspondent messages as long as the rate limitation is applied. The
node MUST stop retransmitting when it receives a Binding Update. correspondent node MUST stop retransmitting when it receives a
Binding Update.
9.6 Cache Replacement Policy 9.6. Cache Replacement Policy
Conceptually, a node maintains a separate timer for each entry in its Conceptually, a node maintains a separate timer for each entry in its
Binding Cache. When creating or updating a Binding Cache entry in Binding Cache. When creating or updating a Binding Cache entry in
response to a received and accepted Binding Update, the node sets the response to a received and accepted Binding Update, the node sets the
timer for this entry to the specified Lifetime period. Any entry in timer for this entry to the specified Lifetime period. Any entry in
a node's Binding Cache MUST be deleted after the expiration of the a node's Binding Cache MUST be deleted after the expiration of the
Lifetime specified in the Binding Update from which the entry was Lifetime specified in the Binding Update from which the entry was
created or last updated. created or last updated.
Each node's Binding Cache will, by necessity, have a finite size. A Each node's Binding Cache will, by necessity, have a finite size. A
node MAY use any reasonable local policy for managing the space node MAY use any reasonable local policy for managing the space
within its Binding Cache. within its Binding Cache.
A node MAY choose to drop any entry already in its Binding Cache in A node MAY choose to drop any entry already in its Binding Cache in
order to make space for a new entry. For example, a "least-recently order to make space for a new entry. For example, a "least-recently
used" (LRU) strategy for cache entry replacement among entries is used" (LRU) strategy for cache entry replacement among entries should
likely to work well unless the size of the Binding Cache is work well, unless the size of the Binding Cache is substantially
substantially insufficient. When entries are deleted, the insufficient. When entries are deleted, the correspondent node MUST
correspondent node MUST follow the rules in Section 5.2.8 in order to follow the rules in Section 5.2.8 in order to guard the return
guard the return routability procedure against replay attacks. routability procedure against replay attacks.
If the node sends a packet to a destination for which it has dropped If the node sends a packet to a destination for which it has dropped
the entry from its Binding Cache, the packet will be routed through the entry from its Binding Cache, the packet will be routed through
the mobile node's home link. The mobile node can detect this, and the mobile node's home link. The mobile node can detect this and
establish a new binding if necessary. establish a new binding if necessary.
However, if the mobile node believes that the binding still exists, However, if the mobile node believes that the binding still exists,
it may use route optimization and send packets with the Home Address it may use route optimization and send packets with the Home Address
destination option. This can create temporary packet loss, as destination option. This can create temporary packet loss, as
discussed earlier in the context of binding lifetime reductions discussed earlier, in the context of binding lifetime reductions
performed by the correspondent node (Section 9.5.2). performed by the correspondent node (Section 9.5.2).
10. Home Agent Operation 10. Home Agent Operation
10.1 Conceptual Data Structures 10.1. Conceptual Data Structures
Each home agent MUST maintain a Binding Cache and Home Agents List. Each home agent MUST maintain a Binding Cache and Home Agents List.
The rules for maintaining a Binding Cache are the same for home The rules for maintaining a Binding Cache are the same for home
agents and correspondent nodes, and have already been described in agents and correspondent nodes and have already been described in
Section 9.1. Section 9.1.
The Home Agents List is maintained by each home agent, recording The Home Agents List is maintained by each home agent, recording
information about each router on the same link which is acting as a information about each router on the same link that is acting as a
home agent; this list is used by the dynamic home agent address home agent. This list is used by the dynamic home agent address
discovery mechanism. A router is known to be acting as a home agent, discovery mechanism. A router is known to be acting as a home agent,
if it sends a Router Advertisement in which the Home Agent (H) bit is if it sends a Router Advertisement in which the Home Agent (H) bit is
set. When the lifetime for a list entry (defined below) expires, set. When the lifetime for a list entry (defined below) expires,
that entry is removed from the Home Agents List. The Home Agents that entry is removed from the Home Agents List. The Home Agents
List is thus similar to the Default Router List conceptual data List is similar to the Default Router List conceptual data structure
structure maintained by each host for Neighbor Discovery [12]. The maintained by each host for Neighbor Discovery [12]. The Home Agents
Home Agents List MAY be implemented in any manner consistent with the List MAY be implemented in any manner consistent with the external
external behavior described in this document. behavior described in this document.
Each home agent maintains a separate Home Agents List for each link Each home agent maintains a separate Home Agents List for each link
on which it is serving as a home agent. A new entry is created or an on which it is serving as a home agent. A new entry is created or an
existing entry is updated in response to receipt of a valid Router existing entry is updated in response to receipt of a valid Router
Advertisement in which the Home Agent (H) bit is set. Each Home Advertisement in which the Home Agent (H) bit is set. Each Home
Agents List entry conceptually contains the following fields: Agents List entry conceptually contains the following fields:
o The link-local IP address of a home agent on the link. This o The link-local IP address of a home agent on the link. This
address is learned through the Source Address of the Router address is learned through the Source Address of the Router
Advertisements [12] received from the router. Advertisements [12] received from the router.
o One or more global IP addresses for this home agent. Global o One or more global IP addresses for this home agent. Global
addresses are learned through Prefix Information options with the addresses are learned through Prefix Information options with the
Router Address (R) bit set, received in Router Advertisements from Router Address (R) bit set and received in Router Advertisements
this link-local address. Global addresses for the router in a from this link-local address. Global addresses for the router in
Home Agents List entry MUST be deleted once the prefix associated a Home Agents List entry MUST be deleted once the prefix
with that address is no longer valid [12]. associated with that address is no longer valid [12].
o The remaining lifetime of this Home Agents List entry. If a Home o The remaining lifetime of this Home Agents List entry. If a Home
Agent Information Option is present in a Router Advertisement Agent Information Option is present in a Router Advertisement
received from a home agent, the lifetime of the Home Agents List received from a home agent, the lifetime of the Home Agents List
entry representing that home agent is initialized from the Home entry representing that home agent is initialized from the Home
Agent Lifetime field in the option (if present); otherwise, the Agent Lifetime field in the option (if present); otherwise, the
lifetime is initialized from the Router Lifetime field in the lifetime is initialized from the Router Lifetime field in the
received Router Advertisement. If Home Agents List entry lifetime received Router Advertisement. If Home Agents List entry lifetime
reaches zero, the entry MUST be deleted from the Home Agents List. reaches zero, the entry MUST be deleted from the Home Agents List.
o The preference for this home agent; higher values indicate a more o The preference for this home agent; higher values indicate a more
preferable home agent. The preference value is taken from the preferable home agent. The preference value is taken from the
Home Agent Preference field in the received Router Advertisement, Home Agent Preference field in the received Router Advertisement,
if the Router Advertisement contains a Home Agent Information if the Router Advertisement contains a Home Agent Information
Option, and is otherwise set to the default value of 0. A home Option and is otherwise set to the default value of 0. A home
agent uses this preference in ordering the Home Agents List when agent uses this preference in ordering the Home Agents List when
it sends an ICMP Home Agent Address Discovery message. it sends an ICMP Home Agent Address Discovery message.
10.2 Processing Mobility Headers 10.2. Processing Mobility Headers
All IPv6 home agents MUST observe the rules described in Section 9.2 All IPv6 home agents MUST observe the rules described in Section 9.2
when processing Mobility Headers. when processing Mobility Headers.
10.3 Processing Bindings 10.3. Processing Bindings
10.3.1 Primary Care-of Address Registration 10.3.1. Primary Care-of Address Registration
When a node receives a Binding Update, it MUST validate it and When a node receives a Binding Update, it MUST validate it and
determine the type of Binding Update according to the steps described determine the type of Binding Update according to the steps described
in Section 9.5.1. Furthermore, it MUST authenticate the Binding in Section 9.5.1. Furthermore, it MUST authenticate the Binding
Update as described in Section 5.1. An authorization step specific Update as described in Section 5.1. An authorization step specific
for the home agent is also needed to ensure that only the right node for the home agent is also needed to ensure that only the right node
can control a particular home address. This is provided through the can control a particular home address. This is provided through the
home address unequivocally identifying the security association that home address unequivocally identifying the security association that
must be used. must be used.
This section describes the processing of a valid and authorized This section describes the processing of a valid and authorized
Binding Update, when it requests the registration of the mobile Binding Update when it requests the registration of the mobile node's
node's primary care-of address. primary care-of address.
To begin processing the Binding Update, the home agent MUST perform To begin processing the Binding Update, the home agent MUST perform
the following sequence of tests: the following sequence of tests:
o If the node implements only correspondent node functionality, or o If the node implements only correspondent node functionality, or
has not been configured to act as a home agent, then the node MUST has not been configured to act as a home agent, then the node MUST
reject the Binding Update. The node MUST then also return a reject the Binding Update. The node MUST also return a Binding
Binding Acknowledgement to the mobile node, in which the Status Acknowledgement to the mobile node, in which the Status field is
field is set to 131 (home registration not supported). set to 131 (home registration not supported).
o Else, if the home address for the binding (the Home Address field o Else, if the home address for the binding (the Home Address field
in the packet's Home Address option) is not an on-link IPv6 in the packet's Home Address option) is not an on-link IPv6
address with respect to the home agent's current Prefix List, then address with respect to the home agent's current Prefix List, then
the home agent MUST reject the Binding Update and SHOULD return a the home agent MUST reject the Binding Update and SHOULD return a
Binding Acknowledgement to the mobile node, in which the Status Binding Acknowledgement to the mobile node, in which the Status
field is set to 132 (not home subnet). field is set to 132 (not home subnet).
o Else, if the home agent chooses to reject the Binding Update for o Else, if the home agent chooses to reject the Binding Update for
any other reason (e.g., insufficient resources to serve another any other reason (e.g., insufficient resources to serve another
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the rejection. the rejection.
o A Home Address destination option MUST be present in the message. o A Home Address destination option MUST be present in the message.
It MUST be validated as described in Section 9.3.1 with the It MUST be validated as described in Section 9.3.1 with the
following additional rule. The Binding Cache entry existence test following additional rule. The Binding Cache entry existence test
MUST NOT be done for IPsec packets when the Home Address option MUST NOT be done for IPsec packets when the Home Address option
contains an address for which the receiving node could act as a contains an address for which the receiving node could act as a
home agent. home agent.
If home agent accepts the Binding Update, it MUST then create a new If home agent accepts the Binding Update, it MUST then create a new
entry in its Binding Cache for this mobile node, or update its entry in its Binding Cache for this mobile node or update its
existing Binding Cache entry, if such an entry already exists. The existing Binding Cache entry, if such an entry already exists. The
Home Address field as received in the Home Address option provides Home Address field as received in the Home Address option provides
the home address of the mobile node. the home address of the mobile node.
The home agent MUST mark this Binding Cache entry as a home The home agent MUST mark this Binding Cache entry as a home
registration to indicate that the node is serving as a home agent for registration to indicate that the node is serving as a home agent for
this binding. Binding Cache entries marked as a home registration this binding. Binding Cache entries marked as a home registration
MUST be excluded from the normal cache replacement policy used for MUST be excluded from the normal cache replacement policy used for
the Binding Cache (Section 9.6) and MUST NOT be removed from the the Binding Cache (Section 9.6) and MUST NOT be removed from the
Binding Cache until the expiration of the Lifetime period. Binding Cache until the expiration of the Lifetime period.
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address, the home agent MUST perform Duplicate Address Detection [13] address, the home agent MUST perform Duplicate Address Detection [13]
on the mobile node's home link before returning the Binding on the mobile node's home link before returning the Binding
Acknowledgement. This ensures that no other node on the home link Acknowledgement. This ensures that no other node on the home link
was using the mobile node's home address when the Binding Update was using the mobile node's home address when the Binding Update
arrived. If this Duplicate Address Detection fails for the given arrived. If this Duplicate Address Detection fails for the given
home address or an associated link local address, then the home agent home address or an associated link local address, then the home agent
MUST reject the complete Binding Update and MUST return a Binding MUST reject the complete Binding Update and MUST return a Binding
Acknowledgement to the mobile node, in which the Status field is set Acknowledgement to the mobile node, in which the Status field is set
to 134 (Duplicate Address Detection failed). When the home agent to 134 (Duplicate Address Detection failed). When the home agent
sends a successful Binding Acknowledgement to the mobile node, the sends a successful Binding Acknowledgement to the mobile node, the
home agent assures to the mobile node that its address(es) will home agent assures to the mobile node that its address(es) will be
continue to be kept unique by the home agent at least as long as the kept unique by the home agent for as long as the lifetime was granted
lifetime granted for the binding is not over. for the binding.
The specific addresses which are to be tested before accepting the The specific addresses, which are to be tested before accepting the
Binding Update, and later to be defended by performing Duplicate Binding Update and later to be defended by performing Duplicate
Address Detection, depend on the setting of the Link-Local Address Address Detection, depend on the setting of the Link-Local Address
Compatibility (L) bit, as follows: Compatibility (L) bit, as follows:
o L=0: Defend only the given address. Do not derive a link-local o L=0: Defend only the given address. Do not derive a link-local
address. address.
o L=1: Defend both the given non link-local unicast (home) address o L=1: Defend both the given non link-local unicast (home) address
and the derived link-local. The link-local address is derived by and the derived link-local. The link-local address is derived by
replacing the subnet prefix in the mobile node's home address with replacing the subnet prefix in the mobile node's home address with
the link-local prefix. the link-local prefix.
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The lifetime of the Binding Cache entry depends on a number of The lifetime of the Binding Cache entry depends on a number of
factors: factors:
o The lifetime for the Binding Cache entry MUST NOT be greater than o The lifetime for the Binding Cache entry MUST NOT be greater than
the Lifetime value specified in the Binding Update. the Lifetime value specified in the Binding Update.
o The lifetime for the Binding Cache entry MUST NOT be greater than o The lifetime for the Binding Cache entry MUST NOT be greater than
the remaining valid lifetime for the subnet prefix in the mobile the remaining valid lifetime for the subnet prefix in the mobile
node's home address specified with the Binding Update. The node's home address specified with the Binding Update. The
remaining valid lifetime for this prefix is determined by the home remaining valid lifetime for this prefix is determined by the home
agent based on its own Prefix List entry for this prefix [12]. agent based on its own Prefix List entry [12].
The remaining preferred lifetime SHOULD NOT have any impact on the The remaining preferred lifetime SHOULD NOT have any impact on the
lifetime for the binding cache entry. lifetime for the binding cache entry.
The home agent MUST remove a binding when the valid lifetime of The home agent MUST remove a binding when the valid lifetime of
the prefix associated with it expires. the prefix associated with it expires.
o The home agent MAY further decrease the specified lifetime for the o The home agent MAY further decrease the specified lifetime for the
binding, for example based on a local policy. The resulting binding, for example based on a local policy. The resulting
lifetime is stored by the home agent in the Binding Cache entry, lifetime is stored by the home agent in the Binding Cache entry,
and this Binding Cache entry MUST be deleted by the home agent and this Binding Cache entry MUST be deleted by the home agent
after the expiration of this lifetime. after the expiration of this lifetime.
Regardless of the setting of the Acknowledge (A) bit in the Binding Regardless of the setting of the Acknowledge (A) bit in the Binding
Update, the home agent MUST return a Binding Acknowledgement to the Update, the home agent MUST return a Binding Acknowledgement to the
mobile node, constructed as follows: mobile node constructed as follows:
o The Status field MUST be set to a value indicating success. The o The Status field MUST be set to a value indicating success. The
value 1 (accepted but prefix discovery necessary) MUST be used if value 1 (accepted but prefix discovery necessary) MUST be used if
the subnet prefix of the specified home address is deprecated, the subnet prefix of the specified home address is deprecated, or
becomes deprecated during the lifetime of the binding, or becomes becomes deprecated during the lifetime of the binding, or becomes
invalid at the end of the lifetime. The value 0 MUST be used invalid at the end of the lifetime. The value 0 MUST be used
otherwise. For the purposes of comparing the binding and prefix otherwise. For the purposes of comparing the binding and prefix
lifetimes, the prefix lifetimes are first converted into units of lifetimes, the prefix lifetimes are first converted into units of
four seconds by ignoring the two least significant bits. four seconds by ignoring the two least significant bits.
o The Key Management Mobility Capability (K) bit is set if the o The Key Management Mobility Capability (K) bit is set if the
following conditions are all fulfilled, and cleared otherwise: following conditions are all fulfilled, and cleared otherwise:
* The Key Management Mobility Capability (K) bit was set in the * The Key Management Mobility Capability (K) bit was set in the
Binding Update. Binding Update.
* The IPsec security associations between the mobile node and the * The IPsec security associations between the mobile node and the
home agent have been established dynamically. home agent have been established dynamically.
* The home agent has the capability to update its endpoint in the * The home agent has the capability to update its endpoint in the
used key management protocol to the new care-of address every used key management protocol to the new care-of address every
time it moves time it moves.
Depending on the final value of the bit in the Binding Depending on the final value of the bit in the Binding
Acknowledgement, the home agent SHOULD perform the following Acknowledgement, the home agent SHOULD perform the following
actions: actions:
K = 0 K = 0
Discard key management connections, if any, to the old care-of Discard key management connections, if any, to the old care-of
address. If the mobile node did not have a binding before address. If the mobile node did not have a binding before
sending this Binding Update, discard the connections to the sending this Binding Update, discard the connections to the
home address. home address.
K = 1 K = 1
Move the peer endpoint of the key management protocol Move the peer endpoint of the key management protocol
connection, if any, to the new care-of address. For an IKE connection, if any, to the new care-of address. For an IKE
phase 1 connection, this means that any IKE packets sent to the phase 1 connection, this means that any IKE packets sent to the
peer are sent to this address, and packets from this address peer are sent to this address, and packets from this address
with the original ISAKMP cookies are accepted. with the original ISAKMP cookies are accepted.
Note that Section 2.5.3 in RFC 2408 [8] Section 2.5.3 states Note that RFC 2408 [8] Section 2.5.3 gives specific rules that
three specifies rules that ISAKMP cookies must satisfy: they ISAKMP cookies must satisfy: they must depend on specific
must depend on specific parties and they can only have been parties and can only be generated by the entity itself. Then
generated by the entity itself. Then it recommends a it recommends a particular way to do this, namely a hash of IP
particular way to do this, namely a hash of IP addresses. With addresses. With the K bit set to 1, the recommended
the K bit set to 1, the recommended implementation technique implementation technique does not work directly. To satisfy
does not work directly. To satisfy the two rules, the specific the two rules, the specific parties must be treated as the
parties must be treated as the original IP addresses, not the original IP addresses, not the ones in use at the specific
ones in use at the specific moment. moment.
o The Sequence Number field MUST be copied from the Sequence Number o The Sequence Number field MUST be copied from the Sequence Number
given in the Binding Update. given in the Binding Update.
o The Lifetime field MUST be set to the remaining lifetime for the o The Lifetime field MUST be set to the remaining lifetime for the
binding as set by the home agent in its home registration Binding binding as set by the home agent in its home registration Binding
Cache entry for the mobile node, as described above. Cache entry for the mobile node, as described above.
o If the home agent stores the Binding Cache entry in nonvolatile o If the home agent stores the Binding Cache entry in nonvolatile
storage, then the Binding Refresh Advice mobility option MUST be storage, then the Binding Refresh Advice mobility option MUST be
omitted. Otherwise, the home agent MAY include this option to omitted. Otherwise, the home agent MAY include this option to
suggest that the mobile node refreshes its binding sooner than the suggest that the mobile node refreshes its binding before the
actual lifetime of the binding ends. actual lifetime of the binding ends.
If the Binding Refresh Advice mobility option is present, the If the Binding Refresh Advice mobility option is present, the
Refresh Interval field in the option MUST be set to a value less Refresh Interval field in the option MUST be set to a value less
than the Lifetime value being returned in the Binding than the Lifetime value being returned in the Binding
Acknowledgement. This indicates that the mobile node SHOULD Acknowledgement. This indicates that the mobile node SHOULD
attempt to refresh its home registration at the indicated shorter attempt to refresh its home registration at the indicated shorter
interval. The home agent MUST still retain the registration for interval. The home agent MUST still retain the registration for
the Lifetime period, even if the mobile node does not refresh its the Lifetime period, even if the mobile node does not refresh its
registration within the Refresh period. registration within the Refresh period.
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In addition, the home agent MUST follow the procedure defined in In addition, the home agent MUST follow the procedure defined in
Section 10.4.1 to intercept packets on the mobile node's home link Section 10.4.1 to intercept packets on the mobile node's home link
addressed to the mobile node, while the home agent is serving as the addressed to the mobile node, while the home agent is serving as the
home agent for this mobile node. The home agent MUST also be home agent for this mobile node. The home agent MUST also be
prepared to accept reverse tunneled packets from the new care-of prepared to accept reverse tunneled packets from the new care-of
address of the mobile node, as described in Section 10.4.5. Finally, address of the mobile node, as described in Section 10.4.5. Finally,
the home agent MUST also propagate new home network prefixes, as the home agent MUST also propagate new home network prefixes, as
described in Section 10.6. described in Section 10.6.
10.3.2 Primary Care-of Address De-Registration 10.3.2. Primary Care-of Address De-Registration
A binding may need to be de-registered when the mobile node returns A binding may need to be de-registered when the mobile node returns
home, or when the mobile node knows that it will soon not have any home or when the mobile node knows that it will not have any care-of
care-of addresses in the visited network. addresses in the visited network.
A Binding Update is validated and authorized in the manner described A Binding Update is validated and authorized in the manner described
in the previous section. This section describes the processing of a in the previous section; note that when the mobile node de-registers
valid Binding Update that requests the receiving node to no longer when it is at home, it may not include the Home Address destination
serve as its home agent, de-registering its primary care-of address. option, in which case the mobile node's home address is the source IP
address of the de-registration Binding Update. This section
describes the processing of a valid Binding Update that requests the
receiving node to no longer serve as its home agent, de-registering
its primary care-of address.
To begin processing the Binding Update, the home agent MUST perform To begin processing the Binding Update, the home agent MUST perform
the following test: the following test:
o If the receiving node has no entry marked as a home registration o If the receiving node has no entry marked as a home registration
in its Binding Cache for this mobile node, then this node MUST in its Binding Cache for this mobile node, then this node MUST
reject the Binding Update and SHOULD return a Binding reject the Binding Update and SHOULD return a Binding
Acknowledgement to the mobile node, in which the Status field is Acknowledgement to the mobile node, in which the Status field is
set to 133 (not home agent for this mobile node). set to 133 (not home agent for this mobile node).
If the home agent does not reject the Binding Update as described If the home agent does not reject the Binding Update as described
above, then it MUST delete any existing entry in its Binding Cache above, then it MUST delete any existing entry in its Binding Cache
for this mobile node. Then, the home agent MUST return a Binding for this mobile node. Then, the home agent MUST return a Binding
Acknowledgement to the mobile node, constructed as follows: Acknowledgement to the mobile node, constructed as follows:
o The Status field MUST be set to a value 0, indicating success. o The Status field MUST be set to a value 0, indicating success.
o The Key Management Mobility Capability (K) bit is set or cleared, o The Key Management Mobility Capability (K) bit is set or cleared
and actions based on its value are performed as described in the and actions based on its value are performed as described in the
previous section. The mobile node's home address is used as its previous section. The mobile node's home address is used as its
new care-of address for the purposes of moving the key management new care-of address for the purposes of moving the key management
connection to a new endpoint. connection to a new endpoint.
o The Sequence Number field MUST be copied from the Sequence Number o The Sequence Number field MUST be copied from the Sequence Number
given in the Binding Update. given in the Binding Update.
o The Lifetime field MUST be set to zero. o The Lifetime field MUST be set to zero.
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The rules for selecting the Destination IP address (and, if required, The rules for selecting the Destination IP address (and, if required,
routing header construction) for the Binding Acknowledgement to the routing header construction) for the Binding Acknowledgement to the
mobile node are the same as in the previous section. When the Status mobile node are the same as in the previous section. When the Status
field in the Binding Acknowledgement is greater than or equal to 128 field in the Binding Acknowledgement is greater than or equal to 128
and the Source Address of the Binding Update is on the home link, the and the Source Address of the Binding Update is on the home link, the
home agent MUST send it to the mobile node's link layer address home agent MUST send it to the mobile node's link layer address
(retrieved either from the Binding Update or through Neighbor (retrieved either from the Binding Update or through Neighbor
Solicitation). Solicitation).
10.4 Packet Processing 10.4. Packet Processing
10.4.1 Intercepting Packets for a Mobile Node 10.4.1. Intercepting Packets for a Mobile Node
While a node is serving as the home agent for mobile node it MUST While a node is serving as the home agent for mobile node it MUST
attempt to intercept packets on the mobile node's home link that are attempt to intercept packets on the mobile node's home link that are
addressed to the mobile node. addressed to the mobile node.
In order to do this, when a node begins serving as the home agent it In order to do this, when a node begins serving as the home agent it
MUST multicast onto the home link a Neighbor Advertisement message MUST multicast onto the home link a Neighbor Advertisement message
[12] on behalf of the mobile node. For the home address specified in [12] on behalf of the mobile node. For the home address specified in
the Binding Update, the home agent sends a Neighbor Advertisement the Binding Update, the home agent sends a Neighbor Advertisement
message [12] to the all-nodes multicast address on the home link, to message [12] to the all-nodes multicast address on the home link to
advertise the home agent's own link-layer address for this IP address advertise the home agent's own link-layer address for this IP address
on behalf of the mobile node. If the Link-Layer Address on behalf of the mobile node. If the Link-Layer Address
Compatibility (L) flag has been specified in the Binding Update, the Compatibility (L) flag has been specified in the Binding Update, the
home agent MUST do the same for the link-local address of the mobile home agent MUST do the same for the link-local address of the mobile
node. node.
All fields in each such Neighbor Advertisement message SHOULD be set All fields in each Neighbor Advertisement message SHOULD be set in
in the same way they would be set by the mobile node itself if the same way they would be set by the mobile node if it was sending
sending this Neighbor Advertisement [12] while at home, with the this Neighbor Advertisement [12] while at home, with the following
following exceptions: exceptions:
o The Target Address in the Neighbor Advertisement MUST be set to o The Target Address in the Neighbor Advertisement MUST be set to
the specific IP address for the mobile node. the specific IP address for the mobile node.
o The Advertisement MUST include a Target Link-layer Address option o The Advertisement MUST include a Target Link-layer Address option
specifying the home agent's link-layer address. specifying the home agent's link-layer address.
o The Router (R) bit in the Advertisement MUST be set to zero. o The Router (R) bit in the Advertisement MUST be set to zero.
o The Solicited Flag (S) in the Advertisement MUST NOT be set, since o The Solicited Flag (S) in the Advertisement MUST NOT be set, since
it was not solicited by any Neighbor Solicitation. it was not solicited by any Neighbor Solicitation.
o The Override Flag (O) in the Advertisement MUST be set, indicating o The Override Flag (O) in the Advertisement MUST be set, indicating
that the Advertisement SHOULD override any existing Neighbor Cache that the Advertisement SHOULD override any existing Neighbor Cache
entry at any node receiving it. entry at any node receiving it.
o The Source Address in the IPv6 header MUST be set to the home o The Source Address in the IPv6 header MUST be set to the home
agent's IP address on the interface used to send the agent's IP address on the interface used to send the
advertisement. advertisement.
Any node on the home link receiving one of the Neighbor Advertisement Any node on the home link that receives one of the Neighbor
messages described above will thus update its Neighbor Cache to Advertisement messages (described above) will update its Neighbor
associate the mobile node's address with the home agent's link layer Cache to associate the mobile node's address with the home agent's
address, causing it to transmit any future packets normally destined link layer address, causing it to transmit any future packets
to the mobile node to the mobile node's home agent. Since normally destined to the mobile node to the mobile node's home agent.
multicasting on the local link (such as Ethernet) is typically not
guaranteed to be reliable, the home agent MAY retransmit this Since multicasting on the local link (such as Ethernet) is typically
not guaranteed to be reliable, the home agent MAY retransmit this
Neighbor Advertisement message up to MAX_NEIGHBOR_ADVERTISEMENT (see Neighbor Advertisement message up to MAX_NEIGHBOR_ADVERTISEMENT (see
[12]) times to increase its reliability. It is still possible that [12]) times to increase its reliability. It is still possible that
some nodes on the home link will not receive any of these Neighbor some nodes on the home link will not receive any of the Neighbor
Advertisements, but these nodes will eventually be able to detect the Advertisements, but these nodes will eventually be able to detect the
link-layer address change for the mobile node's address, through use link-layer address change for the mobile node's address through use
of Neighbor Unreachability Detection [12]. of Neighbor Unreachability Detection [12].
While a node is serving as a home agent for some mobile node, the While a node is serving as a home agent for some mobile node, the
home agent uses IPv6 Neighbor Discovery [12] to intercept unicast home agent uses IPv6 Neighbor Discovery [12] to intercept unicast
packets on the home link addressed to the mobile node. In order to packets on the home link addressed to the mobile node. In order to
intercept packets in this way, the home agent MUST act as a proxy for intercept packets in this way, the home agent MUST act as a proxy for
this mobile node, and reply to any received Neighbor Solicitations this mobile node and reply to any received Neighbor Solicitations for
for it. When a home agent receives a Neighbor Solicitation, it MUST it. When a home agent receives a Neighbor Solicitation, it MUST
check if the Target Address specified in the message matches the check if the Target Address specified in the message matches the
address of any mobile node for which it has a Binding Cache entry address of any mobile node for which it has a Binding Cache entry
marked as a home registration. marked as a home registration.
If such an entry exists in the home agent's Binding Cache, the home If such an entry exists in the home agent's Binding Cache, the home
agent MUST reply to the Neighbor Solicitation with a Neighbor agent MUST reply to the Neighbor Solicitation with a Neighbor
Advertisement, giving the home agent's own link-layer address as the Advertisement giving the home agent's own link-layer address as the
link-layer address for the specified Target Address. In addition, link-layer address for the specified Target Address. In addition,
the Router (R) bit in the Advertisement MUST be set to zero. Acting the Router (R) bit in the Advertisement MUST be set to zero. Acting
as a proxy in this way allows other nodes on the mobile node's home as a proxy in this way allows other nodes on the mobile node's home
link to resolve the mobile node's address, and allows the home agent link to resolve the mobile node's address and for the home agent to
to defend these addresses on the home link for Duplicate Address defend these addresses on the home link for Duplicate Address
Detection [12]. Detection [12].
10.4.2 Processing Intercepted Packets 10.4.2. Processing Intercepted Packets
For any packet sent to a mobile node from the mobile node's home For any packet sent to a mobile node from the mobile node's home
agent (for which the home agent is the original sender of the agent (in which the home agent is the original sender of the packet),
packet), the home agent is operating as a correspondent node of the the home agent is operating as a correspondent node of the mobile
mobile node for this packet and the procedures described in Section node for this packet and the procedures described in Section 9.3.2
9.3.2 apply. The home agent then uses a routing header to route the apply. The home agent then uses a routing header to route the packet
packet to the mobile node by way of the primary care-of address in to the mobile node by way of the primary care-of address in the home
the home agent's Binding Cache. agent's Binding Cache.
While the mobile node is away from home, the home agent intercepts While the mobile node is away from home, the home agent intercepts
any packets on the home link addressed to the mobile node's home any packets on the home link addressed to the mobile node's home
address, as described in Section 10.4.1. In order to forward each address, as described in Section 10.4.1. In order to forward each
intercepted packet to the mobile node, the home agent MUST tunnel the intercepted packet to the mobile node, the home agent MUST tunnel the
packet to the mobile node using IPv6 encapsulation [15]. When a home packet to the mobile node using IPv6 encapsulation [15]. When a home
agent encapsulates an intercepted packet for forwarding to the mobile agent encapsulates an intercepted packet for forwarding to the mobile
node, the home agent sets the Source Address in the new tunnel IP node, the home agent sets the Source Address in the new tunnel IP
header to the home agent's own IP address, and sets the Destination header to the home agent's own IP address and sets the Destination
Address in the tunnel IP header to the mobile node's primary care-of Address in the tunnel IP header to the mobile node's primary care-of
address. When received by the mobile node, normal processing of the address. When received by the mobile node, normal processing of the
tunnel header [15] will result in decapsulation and processing of the tunnel header [15] will result in decapsulation and processing of the
original packet by the mobile node. original packet by the mobile node.
However, packets addressed to the mobile node's link-local address However, packets addressed to the mobile node's link-local address
MUST NOT be tunneled to the mobile node. Instead, such a packet MUST MUST NOT be tunneled to the mobile node. Instead, these packets MUST
be discarded, and the home agent SHOULD return an ICMP Destination be discarded and the home agent SHOULD return an ICMP Destination
Unreachable, Code 3, message to the packet's Source Address (unless Unreachable, Code 3, message to the packet's Source Address (unless
this Source Address is a multicast address). Packets addressed to this Source Address is a multicast address). Packets addressed to
the mobile node's site-local address SHOULD NOT be tunneled to the the mobile node's site-local address SHOULD NOT be tunneled to the
mobile node by default. mobile node by default.
Interception and tunneling of the following multicast addressed Interception and tunneling of the following multicast addressed
packets on the home network are only done if the home agent supports packets on the home network are only done if the home agent supports
multicast group membership control messages from the mobile node as multicast group membership control messages from the mobile node as
described in the next section. Tunneling of multicast packets to a described in the next section. Tunneling of multicast packets to a
mobile node follows similar limitations to those defined above for mobile node follows similar limitations to those defined above for
unicast packets addressed to the mobile node's link-local and unicast packets addressed to the mobile node's link-local and site-
site-local addresses. Multicast packets addressed to a multicast local addresses. Multicast packets addressed to a multicast address
address with link-local scope [3], to which the mobile node is with link-local scope [3], to which the mobile node is subscribed,
subscribed, MUST NOT be tunneled to the mobile node; such packets MUST NOT be tunneled to the mobile node. These packets SHOULD be
SHOULD be silently discarded (after delivering to other local silently discarded (after delivering to other local multicast
multicast recipients). Multicast packets addressed to a multicast recipients). Multicast packets addressed to a multicast address with
address with scope larger than link-local but smaller than global a scope larger than link-local, but smaller than global (e.g., site-
(e.g., site-local and organization-local [3]), to which the mobile local and organization-local [3], to which the mobile node is
node is subscribed, SHOULD NOT be tunneled to the mobile node. subscribed, SHOULD NOT be tunneled to the mobile node. Multicast
Multicast packets addressed with a global scope to which the mobile packets addressed with a global scope, to which the mobile node has
node has successfully subscribed MUST be tunneled to the mobile node. successfully subscribed, MUST be tunneled to the mobile node.
Before tunneling a packet to the mobile node, the home agent MUST Before tunneling a packet to the mobile node, the home agent MUST
perform any IPsec processing as indicated by the security policy data perform any IPsec processing as indicated by the security policy data
base. base.
10.4.3 Multicast Membership Control 10.4.3. Multicast Membership Control
This section is a prerequisite for the multicast data packet This section is a prerequisite for the multicast data packet
forwarding described in the previous section. If this support is not forwarding, described in the previous section. If this support is
provided, multicast group membership control messages are silently not provided, multicast group membership control messages are
ignored. silently ignored.
In order to forward multicast data packets from the home network to In order to forward multicast data packets from the home network to
all the proper mobile nodes the home agent SHOULD be capable of all the proper mobile nodes, the home agent SHOULD be capable of
receiving tunneled multicast group membership control information receiving tunneled multicast group membership control information
from the mobile node in order to determine which groups the mobile from the mobile node in order to determine which groups the mobile
node has subscribed to. These multicast group membership messages node has subscribed to. These multicast group membership messages
are Listener Report messages specified MLD [17] or in other protocols are Listener Report messages specified in MLD [17] or in other
such as [37]. protocols such as [37].
The messages are issued by the mobile node but sent through the The messages are issued by the mobile node, but sent through the
reverse tunnel to the home agent. These messages are issued whenever reverse tunnel to the home agent. These messages are issued whenever
the mobile node decides to enable reception of packets for a the mobile node decides to enable reception of packets for a
multicast group or in response to an MLD Query from the home agent. multicast group or in response to an MLD Query from the home agent.
The mobile node will also issue multicast group control messages to The mobile node will also issue multicast group control messages to
disable reception of multicast packets when it is no longer disable reception of multicast packets when it is no longer
interested in receiving multicasts for a particular group. interested in receiving multicasts for a particular group.
To obtain the mobile node's current multicast group membership the To obtain the mobile node's current multicast group membership the
home agent must periodically transmit MLD Query messages through the home agent must periodically transmit MLD Query messages through the
tunnel to the mobile node. These MLD periodic transmissions will tunnel to the mobile node. These MLD periodic transmissions will
ensure the home agent has an accurate record of the groups in which ensure the home agent has an accurate record of the groups in which
the mobile node is interested despite packet losses of the mobile the mobile node is interested despite packet losses of the mobile
node's MLD group membership messages. node's MLD group membership messages.
All MLD packets are sent directly between the mobile node and the All MLD packets are sent directly between the mobile node and the
home agent. Since all these packets are destined to a link-scope home agent. Since all of these packets are destined to a link-scope
multicast address and have a hop limit of 1, there is no direct multicast address and have a hop limit of 1, there is no direct
forwarding of such packets between the home network and the mobile forwarding of such packets between the home network and the mobile
node. The MLD packets between the mobile node and the home agent are node. The MLD packets between the mobile node and the home agent are
encapsulated within the same tunnel header used for other packet encapsulated within the same tunnel header used for other packet
flows between the mobile node and home agent. flows between the mobile node and home agent.
Note that at this time, even though a link-local source is used on Note that at this time, even though a link-local source is used on
MLD packets, no functionality depends on these addresses being MLD packets, no functionality depends on these addresses being
unique, nor do they elicit direct responses. All MLD messages are unique, nor do they elicit direct responses. All MLD messages are
sent to multicast destinations. To avoid ambiguity on the home agent sent to multicast destinations. To avoid ambiguity on the home
due to mobile nodes which may choose identical link-local source agent, due to mobile nodes which may choose identical link-local
addresses for their MLD function it is necessary for the home agent source addresses for their MLD function, it is necessary for the home
to identify which mobile node was actually the issuer of a particular agent to identify which mobile node was actually the issuer of a
MLD message. This may be accomplished by noting which tunnel such an particular MLD message. This may be accomplished by noting which
MLD arrived by, which IPsec SA was used, or by other distinguishing tunnel such an MLD arrived by, which IPsec SA was used, or by other
means. distinguishing means.
This specification puts no requirement on how the functions in this This specification puts no requirement on how the functions in this
section and the multicast forwarding in Section 10.4.2 are to be section and the multicast forwarding in Section 10.4.2 are to be
achieved. At the time of this writing it was thought that a full achieved. At the time of this writing it was thought that a full
IPv6 multicast router function would be necessary on the home agent, IPv6 multicast router function would be necessary on the home agent,
but it may be possible to achieve the same effects through a "proxy but it may be possible to achieve the same effects through a "proxy
MLD" application coupled with kernel multicast forwarding. This may MLD" application coupled with kernel multicast forwarding. This may
be the subject of future specifications. be the subject of future specifications.
10.4.4 Stateful Address Autoconfiguration 10.4.4. Stateful Address Autoconfiguration
This section describes how home agents support the use of stateful This section describes how home agents support the use of stateful
address autoconfiguration mechanisms such as DHCPv6 [29] from the address autoconfiguration mechanisms such as DHCPv6 [29] from the
mobile nodes. If this support is not provided, then the M and O bits mobile nodes. If this support is not provided, then the M and O bits
must remain cleared on the Mobile Prefix Advertisement Messages. Any must remain cleared on the Mobile Prefix Advertisement Messages. Any
mobile node which sends DHCPv6 messages to the home agent without mobile node which sends DHCPv6 messages to the home agent without
this support will not receive a response. this support will not receive a response.
If DHCPv6 is used, packets are sent with link-local source addresses If DHCPv6 is used, packets are sent with link-local source addresses
either to a link-scope multicast address or a link-local address. either to a link-scope multicast address or a link-local address.
Mobile nodes desiring to locate a DHCPv6 service may reverse tunnel Mobile nodes desiring to locate a DHCPv6 service may reverse tunnel
standard DHCPv6 packets to the home agent. Since these link-scope standard DHCPv6 packets to the home agent. Since these link-scope
packets cannot be forwarded onto the home network it is necessary for packets cannot be forwarded onto the home network, it is necessary
the home agent to either implement a DHCPv6 relay agent or a DHCPv6 for the home agent to either implement a DHCPv6 relay agent or a
server function itself. The arriving tunnel or IPsec SA of DHCPv6 DHCPv6 server function itself. The arriving tunnel or IPsec SA of
link-scope messages from the mobile node must be noted so that DHCPv6 DHCPv6 link-scope messages from the mobile node must be noted so that
responses may be sent back to the appropriate mobile node. DHCPv6 DHCPv6 responses may be sent back to the appropriate mobile node.
messages sent to the mobile node with a link-local destination must DHCPv6 messages sent to the mobile node with a link-local destination
be tunneled within the same tunnel header used for other packet must be tunneled within the same tunnel header used for other packet
flows. flows.
10.4.5 Handling Reverse Tunneled Packets 10.4.5. Handling Reverse Tunneled Packets
Unless a binding has been established between the mobile node and a Unless a binding has been established between the mobile node and a
correspondent node, traffic from the mobile node to the correspondent correspondent node, traffic from the mobile node to the correspondent
node goes through a reverse tunnel. Home agents MUST support reverse node goes through a reverse tunnel. Home agents MUST support reverse
tunneling as follows: tunneling as follows:
o The tunneled traffic arrives to the home agent's address using o The tunneled traffic arrives to the home agent's address using
IPv6 encapsulation [15]. IPv6 encapsulation [15].
o Depending on the security policies used by the home agent, reverse o Depending on the security policies used by the home agent, reverse
tunneled packets MAY be discarded unless accompanied by a valid tunneled packets MAY be discarded unless accompanied by a valid
ESP header. The support for authenticated reverse tunneling ESP header. The support for authenticated reverse tunneling
allows the home agent to protect the home network and allows the home agent to protect the home network and
correspondent nodes from malicious nodes masquerading as a mobile correspondent nodes from malicious nodes masquerading as a mobile
node. node.
o Otherwise, when a home agent decapsulates a tunneled packet from o Otherwise, when a home agent decapsulates a tunneled packet from
the mobile node, the home agent MUST verify that the Source the mobile node, the home agent MUST verify that the Source
Address in the tunnel IP header is the mobile node's primary Address in the tunnel IP header is the mobile node's primary
care-of address. Otherwise any node in the Internet could send care-of address. Otherwise, any node in the Internet could send
traffic through the home agent and escape ingress filtering traffic through the home agent and escape ingress filtering
limitations. This simple check forces the attacker to at least limitations. This simple check forces the attacker to know the
know the current location of the real mobile node and be able to current location of the real mobile node and be able to defeat
defeat ingress filtering. ingress filtering. This check is not necessary if the reverse-
tunneled packet is protected by ESP in tunnel mode.
10.4.6 Protecting Return Routability Packets 10.4.6. Protecting Return Routability Packets
The return routability procedure described in Section 5.2.5 assumes The return routability procedure, described in Section 5.2.5, assumes
that the confidentiality of the Home Test Init and Home Test messages that the confidentiality of the Home Test Init and Home Test messages
is protected as they are tunneled between the home agent to the is protected as they are tunneled between the home agent and the
mobile node. Therefore, the home agent MUST support tunnel mode mobile node. Therefore, the home agent MUST support tunnel mode
IPsec ESP for the protection of packets belonging to the return IPsec ESP for the protection of packets belonging to the return
routability procedure. Support for a non-null encryption transform routability procedure. Support for a non-null encryption transform
and authentication algorithm MUST be available. It is not necessary and authentication algorithm MUST be available. It is not necessary
to distinguish between different kinds of packets within the return to distinguish between different kinds of packets during the return
routability procedure. routability procedure.
Security associations are needed to provide this protection. When Security associations are needed to provide this protection. When
the care-of address for the mobile node changes as a result of an the care-of address for the mobile node changes as a result of an
accepted Binding Update, special treatment is needed for the next accepted Binding Update, special treatment is needed for the next
packets sent using these security associations. The home agent MUST packets sent using these security associations. The home agent MUST
set the new care-of address as the destination address of these set the new care-of address as the destination address of these
packets, as if the outer header destination address in the security packets, as if the outer header destination address in the security
association had changed [21]. association had changed [21].
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well as the return routability messages. From the point of view of well as the return routability messages. From the point of view of
the security policy database these messages are indistinguishable. the security policy database these messages are indistinguishable.
When IPsec is used to protect return routability signaling or payload When IPsec is used to protect return routability signaling or payload
packets, this protection MUST only be applied to the return packets, this protection MUST only be applied to the return
routability packets entering the IPv6 encapsulated tunnel interface routability packets entering the IPv6 encapsulated tunnel interface
between the mobile node and the home agent. This can be achieved, between the mobile node and the home agent. This can be achieved,
for instance, by defining the security policy database entries for instance, by defining the security policy database entries
specifically for the tunnel interface. That is, the policy entries specifically for the tunnel interface. That is, the policy entries
are not generally applied on all traffic on the physical interface(s) are not generally applied on all traffic on the physical interface(s)
of the nodes, but rather only on traffic that enters the tunnel. of the nodes, but rather only on traffic that enters the tunnel.
This makes use of per-interface security policy database entries [4], This makes use of per-interface security policy database entries [4]
specific to the tunnel interface (the node's attachment to the tunnel specific to the tunnel interface (the node's attachment to the tunnel
[11]). [11]).
10.5 Dynamic Home Agent Address Discovery 10.5. Dynamic Home Agent Address Discovery
This section describes how a home agent can help mobile nodes to This section describes how a home agent can help mobile nodes to
discover the addresses of the home agents. The home agent keeps discover the addresses of the home agents. The home agent keeps
track of the other home agents on the same link, and responds to track of the other home agents on the same link and responds to
queries sent by the mobile node. queries sent by the mobile node.
10.5.1 Receiving Router Advertisement Messages 10.5.1. Receiving Router Advertisement Messages
For each link on which a router provides service as a home agent, the For each link on which a router provides service as a home agent, the
router maintains a Home Agents List recording information about all router maintains a Home Agents List recording information about all
other home agents on that link. This list is used in the dynamic other home agents on that link. This list is used in the dynamic
home agent address discovery mechanism, described in Section 10.5. home agent address discovery mechanism, described in Section 10.5.
The information for the list is learned through receipt of the The information for the list is learned through receipt of the
periodic unsolicited multicast Router Advertisements, in a manner periodic unsolicited multicast Router Advertisements, in a manner
similar to the Default Router List conceptual data structure similar to the Default Router List conceptual data structure
maintained by each host for Neighbor Discovery [12]. In the maintained by each host for Neighbor Discovery [12]. In the
construction of the Home Agents List, the Router Advertisements are construction of the Home Agents List, the Router Advertisements are
from each other home agent on the link, and the Home Agent (H) bit is from each (other) home agent on the link and the Home Agent (H) bit
set in them. is set in them.
On receipt of a valid Router Advertisement, as defined in the On receipt of a valid Router Advertisement, as defined in the
processing algorithm specified for Neighbor Discovery [12], the home processing algorithm specified for Neighbor Discovery [12], the home
agent performs the following steps, in addition to any steps already agent performs the following steps in addition to any steps already
required of it by Neighbor Discovery: required of it by Neighbor Discovery:
o If the Home Agent (H) bit in the Router Advertisement is not set, o If the Home Agent (H) bit in the Router Advertisement is not set,
delete the sending node's entry in the current Home Agents List delete the sending node's entry in the current Home Agents List
(if one exists). Skip all the following steps. (if one exists). Skip all the following steps.
o Otherwise, extract the Source Address from the IP header of the o Otherwise, extract the Source Address from the IP header of the
Router Advertisement. This is the link-local IP address on this Router Advertisement. This is the link-local IP address on this
link of the home agent sending this Advertisement [12]. link of the home agent sending this Advertisement [12].
skipping to change at page 102, line 49 skipping to change at page 101, line 27
such global addresses to the list of global addresses in this Home such global addresses to the list of global addresses in this Home
Agents List entry. Agents List entry.
A home agent SHOULD maintain an entry in its Home Agents List for A home agent SHOULD maintain an entry in its Home Agents List for
each valid home agent address until that entry's lifetime expires, each valid home agent address until that entry's lifetime expires,
after which time the entry MUST be deleted. after which time the entry MUST be deleted.
As described in Section 11.4.1, a mobile node attempts dynamic home As described in Section 11.4.1, a mobile node attempts dynamic home
agent address discovery by sending an ICMP Home Agent Address agent address discovery by sending an ICMP Home Agent Address
Discovery Request message to the Mobile IPv6 Home-Agents anycast Discovery Request message to the Mobile IPv6 Home-Agents anycast
address [16] for its home IP subnet prefix. A home agent receiving address [16] for its home IP subnet prefix. A home agent receiving a
such a Home Agent Address Discovery Request message that is serving Home Agent Address Discovery Request message that serves this subnet
this subnet SHOULD return an ICMP Home Agent Address Discovery Reply SHOULD return an ICMP Home Agent Address Discovery Reply message to
message to the mobile node, with the Source Address of the Reply the mobile node with the Source Address of the Reply packet set to
packet set to one of the global unicast addresses of the home agent. one of the global unicast addresses of the home agent. The Home
The Home Agent Addresses field in the Reply message is constructed as Agent Addresses field in the Reply message is constructed as follows:
follows:
o The Home Agent Addresses field SHOULD contain all global IP o The Home Agent Addresses field SHOULD contain all global IP
addresses for each home agent currently listed in this home addresses for each home agent currently listed in this home
agent's own Home Agents List (Section 10.1). agent's own Home Agents List (Section 10.1).
o The IP addresses in the Home Agent Addresses field SHOULD be o The IP addresses in the Home Agent Addresses field SHOULD be
listed in order of decreasing preference values, based either on listed in order of decreasing preference values, based either on
the respective advertised preference from a Home Agent Information the respective advertised preference from a Home Agent Information
option or on the default preference of 0 if no preference is option or on the default preference of 0 if no preference is
advertised (or on the configured home agent preference for this advertised (or on the configured home agent preference for this
home agent itself). home agent itself).
o Among home agents with equal preference, their IP addresses in the o Among home agents with equal preference, their IP addresses in the
Home Agent Addresses field SHOULD be listed in an order randomized Home Agent Addresses field SHOULD be listed in an order randomized
with respect to other home agents with equal preference, each time with respect to other home agents with equal preference every time
a Home Agent Address Discovery Reply message is returned by this a Home Agent Address Discovery Reply message is returned by this
home agent. home agent.
o If more than one global IP address is associated with a home o If more than one global IP address is associated with a home
agent, these addresses SHOULD be listed in a randomized order. agent, these addresses SHOULD be listed in a randomized order.
o The home agent SHOULD reduce the number of home agent IP addresses o The home agent SHOULD reduce the number of home agent IP addresses
so that the packet fits within the minimum IPv6 MTU [11]. The so that the packet fits within the minimum IPv6 MTU [11]. The
home agent addresses selected for inclusion in the packet SHOULD home agent addresses selected for inclusion in the packet SHOULD
be those from the complete list with the highest preference. This be those from the complete list with the highest preference. This
limitation avoids the danger of the Reply message packet being limitation avoids the danger of the Reply message packet being
fragmented (or rejected by an intermediate router with an ICMP fragmented (or rejected by an intermediate router with an ICMP
Packet Too Big message [14]). Packet Too Big message [14]).
10.6 Sending Prefix Information to the Mobile Node 10.6. Sending Prefix Information to the Mobile Node
10.6.1 List of Home Network Prefixes 10.6.1. List of Home Network Prefixes
Mobile IPv6 arranges to propagate relevant prefix information to the Mobile IPv6 arranges to propagate relevant prefix information to the
mobile node when it is away from home, so that it may be used in mobile node when it is away from home, so that it may be used in
mobile node home address configuration, and in network renumbering. mobile node home address configuration and in network renumbering.
In this mechanism, mobile nodes away from home receive Mobile Prefix In this mechanism, mobile nodes away from home receive Mobile Prefix
Advertisements messages. These messages include Prefix Information Advertisements messages. These messages include Prefix Information
Options for the prefixes configured on the home subnet interface(s) Options for the prefixes configured on the home subnet interface(s)
of the home agent. of the home agent.
If there are multiple home agents, differences in the advertisements If there are multiple home agents, differences in the advertisements
sent by different home agents can lead to an inability to use a sent by different home agents can lead to an inability to use a
particular home address when changing to another home agent. In particular home address when changing to another home agent. In
order to ensure that the mobile nodes get the same information from order to ensure that the mobile nodes get the same information from
different home agents, it is desired that all the home agents on the different home agents, it is preferred that all of the home agents on
same link be configured in the same manner. the same link be configured in the same manner.
To support this, the home agent monitors prefixes advertised by To support this, the home agent monitors prefixes advertised by
itself and other home agents on the home link. In RFC 2461 [12] it itself and other home agents on the home link. In RFC 2461 [12] it
is acceptable for two routers to advertise different sets of prefixes is acceptable for two routers to advertise different sets of prefixes
on the same link. For home agents such differences should be on the same link. For home agents, the differences should be
detected since for a given home address the mobile node communicates detected for a given home address because the mobile node
only with one home agent at a time and the mobile node needs to know communicates only with one home agent at a time and the mobile node
the full set of prefixes assigned to the home link. All other needs to know the full set of prefixes assigned to the home link.
comparisons of Router Advertisements are as specified in Section All other comparisons of Router Advertisements are as specified in
6.2.7 of RFC 2461. Section 6.2.7 of RFC 2461.
10.6.2 Scheduling Prefix Deliveries 10.6.2. Scheduling Prefix Deliveries
A home agent serving a mobile node will schedule the delivery of new A home agent serving a mobile node will schedule the delivery of the
prefix information to that mobile node when any of the following new prefix information to that mobile node when any of the following
conditions occur: conditions occur:
MUST: MUST:
o The state of the flags changes for the prefix of the mobile node's o The state of the flags changes for the prefix of the mobile node's
registered home address. registered home address.
o The valid or preferred lifetime is reconfigured or changes for any o The valid or preferred lifetime is reconfigured or changes for any
reason other than advancing real time. reason other than advancing real time.
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o The valid or preferred lifetime or the state of the flags changes o The valid or preferred lifetime or the state of the flags changes
for a prefix which is not used in any Binding Cache entry for this for a prefix which is not used in any Binding Cache entry for this
mobile node. mobile node.
The home agent uses the following algorithm to determine when to send The home agent uses the following algorithm to determine when to send
prefix information to the mobile node. prefix information to the mobile node.
o If a mobile node sends a solicitation, answer right away. o If a mobile node sends a solicitation, answer right away.
o If no Mobile Prefix Advertisement has been sent to the mobile node o If no Mobile Prefix Advertisement has been sent to the mobile node
in the last MaxMobPfxAdvInterval (see Section 13) seconds, then in the last MaxMobPfxAdvInterval seconds (see Section 13), then
ensure that a transmission is scheduled. The actual transmission ensure that a transmission is scheduled. The actual transmission
time is randomized as described below. time is randomized as described below.
o If a prefix matching the mobile node's home registration is added o If a prefix matching the mobile node's home registration is added
on the home subnet interface, or if its information changes in any on the home subnet interface or if its information changes in any
way that does not deprecate the mobile node's address, ensure that way that does not deprecate the mobile node's address, ensure that
a transmission is scheduled. The actual transmission time is a transmission is scheduled. The actual transmission time is
randomized as described below. randomized as described below.
o If a home registration expires, cancel any scheduled o If a home registration expires, cancel any scheduled
advertisements to the mobile node. advertisements to the mobile node.
The list of prefixes is sent in its entirety in all cases. The list of prefixes is sent in its entirety in all cases.
If the home agent already has scheduled the transmission of a Mobile If the home agent has already scheduled the transmission of a Mobile
Prefix Advertisement to the mobile node, the home agent replaces the Prefix Advertisement to the mobile node, then the home agent will
advertisement with a new one, to be sent at the scheduled time. replace the advertisement with a new one to be sent at the scheduled
time.
Otherwise, the home agent computes a fresh value for RAND_ADV_DELAY, Otherwise, the home agent computes a fresh value for RAND_ADV_DELAY
the offset from the current time for the scheduled transmission as which offsets from the current time for the scheduled transmission.
follows. First calculate the maximum delay for the scheduled First calculate the maximum delay for the scheduled Advertisement:
Advertisement:
MaxScheduleDelay = min (MaxMobPfxAdvInterval, Preferred Lifetime), MaxScheduleDelay = min (MaxMobPfxAdvInterval, Preferred Lifetime),
where MaxMobPfxAdvInterval is as defined in Section 12. Then compute where MaxMobPfxAdvInterval is as defined in Section 12. Then compute
the final delay for the advertisement: the final delay for the advertisement:
RAND_ADV_DELAY = MinMobPfxAdvInterval + RAND_ADV_DELAY = MinMobPfxAdvInterval +
(rand() % abs(MaxScheduleDelay - MinMobPfxAdvInterval)) (rand() % abs(MaxScheduleDelay - MinMobPfxAdvInterval))
Here rand() returns a random integer value in the range of 0 to the Here rand() returns a random integer value in the range of 0 to the
maximum possible integer value. This computation is expected to maximum possible integer value. This computation is expected to
alleviate bursts of advertisements when prefix information changes. alleviate bursts of advertisements when prefix information changes.
In addition, a home agent MAY further reduce the rate of packet In addition, a home agent MAY further reduce the rate of packet
transmission by further delaying individual advertisements, if needed transmission by further delaying individual advertisements, when
to avoid overwhelming local network resources. The home agent SHOULD necessary to avoid overwhelming local network resources. The home
periodically continue to retransmit an unsolicited Advertisement to agent SHOULD periodically continue to retransmit an unsolicited
the mobile node, until it is acknowledged by the receipt of a Mobile Advertisement to the mobile node, until it is acknowledged by the
Prefix Solicitation from the mobile node. receipt of a Mobile Prefix Solicitation from the mobile node.
The home agent MUST wait PREFIX_ADV_TIMEOUT (see Section 12) before The home agent MUST wait PREFIX_ADV_TIMEOUT (see Section 12) before
the first retransmission, and double the retransmission wait time for the first retransmission and double the retransmission wait time for
every succeeding retransmission, up until a maximum of every succeeding retransmission until a maximum number of
PREFIX_ADV_RETRIES attempts (see Section 12). If the mobile node's PREFIX_ADV_RETRIES attempts (see Section 12) has been tried. If the
bindings expire before the matching Binding Update has been received, mobile node's bindings expire before the matching Binding Update has
then the home agent MUST NOT attempt any more retransmissions, even been received, then the home agent MUST NOT attempt any more
if not all PREFIX_ADV_RETRIES have been retransmitted. If the mobile retransmissions, even if not all PREFIX_ADV_RETRIES have been
node sends another Binding Update without returning home in the retransmitted. In the meantime, if the mobile node sends another
meantime, the home agent SHOULD again begin transmitting the Binding Update without returning home, then the home agent SHOULD
unsolicited Advertisement. begin transmitting the unsolicited Advertisement again.
If some condition as described above occurs on the home link and If some condition, as described above, occurs on the home link and
causes another Prefix Advertisement to be sent to the mobile node, causes another Prefix Advertisement to be sent to the mobile node,
before the mobile node acknowledges a previous transmission, the home before the mobile node acknowledges a previous transmission, the home
agent SHOULD combine any Prefix Information options in the agent SHOULD combine any Prefix Information options in the
unacknowledged Mobile Prefix Advertisement into a new Advertisement. unacknowledged Mobile Prefix Advertisement into a new Advertisement.
The home agent discards the old Advertisement. The home agent then discards the old Advertisement.
10.6.3 Sending Advertisements 10.6.3. Sending Advertisements
When sending a Mobile Prefix Advertisement to the mobile node, the When sending a Mobile Prefix Advertisement to the mobile node, the
home agent MUST construct the packet as follows: home agent MUST construct the packet as follows:
o The Source Address in the packet's IPv6 header MUST be set to the o The Source Address in the packet's IPv6 header MUST be set to the
home agent's IP address to which the mobile node addressed its home agent's IP address to which the mobile node addressed its
current home registration, or its default global home agent current home registration or its default global home agent address
address if no binding exists. if no binding exists.
o If the advertisement was solicited, it MUST be destined to the o If the advertisement was solicited, it MUST be destined to the
source address of the solicitation. If it was triggered by prefix source address of the solicitation. If it was triggered by prefix
changes or renumbering, the advertisement's destination will be changes or renumbering, the advertisement's destination will be
the mobile node's home address in the binding which triggered the the mobile node's home address in the binding which triggered the
rule. rule.
o A type 2 routing header MUST be included with the mobile node's o A type 2 routing header MUST be included with the mobile node's
home address. home address.
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o Set the Managed Address Configuration (M) flag if the o Set the Managed Address Configuration (M) flag if the
corresponding flag has been set in any of the Router corresponding flag has been set in any of the Router
Advertisements from which the prefix information has been learned Advertisements from which the prefix information has been learned
(including the ones sent by this home agent). (including the ones sent by this home agent).
o Set the Other Stateful Configuration (O) flag if the corresponding o Set the Other Stateful Configuration (O) flag if the corresponding
flag has been set in any of the Router Advertisements from which flag has been set in any of the Router Advertisements from which
the prefix information has been learned (including the ones sent the prefix information has been learned (including the ones sent
by this home agent). by this home agent).
10.6.4 Lifetimes for Changed Prefixes 10.6.4. Lifetimes for Changed Prefixes
As described in Section 10.3.1, the lifetime returned by the home As described in Section 10.3.1, the lifetime returned by the home
agent in a Binding Acknowledgement MUST be no greater than the agent in a Binding Acknowledgement MUST not be greater than the
remaining valid lifetime for the subnet prefix in the mobile node's remaining valid lifetime for the subnet prefix in the mobile node's
home address. This limit on the binding lifetime serves to prohibit home address. This limit on the binding lifetime serves to prohibit
use of a mobile node's home address after it becomes invalid. use of a mobile node's home address after it becomes invalid.
11. Mobile Node Operation 11. Mobile Node Operation
11.1 Conceptual Data Structures 11.1. Conceptual Data Structures
Each mobile node MUST maintain a Binding Update List. Each mobile node MUST maintain a Binding Update List.
The Binding Update List records information for each Binding Update The Binding Update List records information for each Binding Update
sent by this mobile node, for which the lifetime of the binding has sent by this mobile node, in which the lifetime of the binding has
not yet expired. The Binding Update List includes all bindings sent not yet expired. The Binding Update List includes all bindings sent
by the mobile node either to its home agent or correspondent nodes. by the mobile node either to its home agent or correspondent nodes.
It also contains Binding Updates which are waiting for the completion It also contains Binding Updates which are waiting for the completion
of the return routability procedure before they can be sent. of the return routability procedure before they can be sent.
However, for multiple Binding Updates sent to the same destination However, for multiple Binding Updates sent to the same destination
address, the Binding Update List contains only the most recent address, the Binding Update List contains only the most recent
Binding Update (i.e., with the greatest Sequence Number value) sent Binding Update (i.e., with the greatest Sequence Number value) sent
to that destination. The Binding Update List MAY be implemented in to that destination. The Binding Update List MAY be implemented in
any manner consistent with the external behavior described in this any manner consistent with the external behavior described in this
document. document.
Each Binding Update List entry conceptually contains the following Each Binding Update List entry conceptually contains the following
fields: fields:
o The IP address of the node to which a Binding Update was sent. o The IP address of the node to which a Binding Update was sent.
o The home address for which that Binding Update was sent. o The home address for which that Binding Update was sent.
o The care-of address sent in that Binding Update. This value is o The care-of address sent in that Binding Update. This value is
necessary for the mobile node to determine if it has sent a necessary for the mobile node to determine if it has sent a
Binding Update giving its new care-of address to this destination Binding Update while giving its new care-of address to this
after changing its care-of address. destination after changing its care-of address.
o The initial value of the Lifetime field sent in that Binding o The initial value of the Lifetime field sent in that Binding
Update. Update.
o The remaining lifetime of that binding. This lifetime is o The remaining lifetime of that binding. This lifetime is
initialized from the Lifetime value sent in the Binding Update and initialized from the Lifetime value sent in the Binding Update and
is decremented until it reaches zero, at which time this entry is decremented until it reaches zero, at which time this entry
MUST be deleted from the Binding Update List. MUST be deleted from the Binding Update List.
o The maximum value of the Sequence Number field sent in previous o The maximum value of the Sequence Number field sent in previous
Binding Updates to this destination. The Sequence Number field is Binding Updates to this destination. The Sequence Number field is
16 bits long, and all comparisons between Sequence Number values 16 bits long and all comparisons between Sequence Number values
MUST be performed modulo 2**16 (see Section 9.5.1). MUST be performed modulo 2**16 (see Section 9.5.1).
o The time at which a Binding Update was last sent to this o The time at which a Binding Update was last sent to this
destination, as needed to implement the rate limiting restriction destination, as needed to implement the rate limiting restriction
for sending Binding Updates. for sending Binding Updates.
o The state of any retransmissions needed for this Binding Update. o The state of any retransmissions needed for this Binding Update.
This state includes the time remaining until the next This state includes the time remaining until the next
retransmission attempt for the Binding Update, and the current retransmission attempt for the Binding Update and the current
state of the exponential back-off mechanism for retransmissions. state of the exponential back-off mechanism for retransmissions.
o A flag specifying whether or not future Binding Updates should be o A flag specifying whether or not future Binding Updates should be
sent to this destination. The mobile node sets this flag in the sent to this destination. The mobile node sets this flag in the
Binding Update List entry when it receives an ICMP Parameter Binding Update List entry when it receives an ICMP Parameter
Problem, Code 1, error message in response to a return routability Problem, Code 1, error message in response to a return routability
message or Binding Update sent to that destination, as described message or Binding Update sent to that destination, as described
in Section 11.3.5. in Section 11.3.5.
The Binding Update List is used to determine whether a particular The Binding Update List is used to determine whether a particular
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o Cookie values used in the Home Test Init and Care-of Test Init o Cookie values used in the Home Test Init and Care-of Test Init
messages. messages.
o Home and care-of keygen tokens received from the correspondent o Home and care-of keygen tokens received from the correspondent
node. node.
o Home and care-of nonce indices received from the correspondent o Home and care-of nonce indices received from the correspondent
node. node.
o The time at which each of the tokens and nonces was received from o The time at which each of the tokens and nonces were received from
this correspondent node, as needed to implement reuse while the correspondent node, as needed to implement reuse while moving.
moving.
11.2 Processing Mobility Headers 11.2. Processing Mobility Headers
All IPv6 mobile nodes MUST observe the rules described in Section 9.2 All IPv6 mobile nodes MUST observe the rules described in Section 9.2
when processing Mobility Headers. when processing Mobility Headers.
11.3 Packet Processing 11.3. Packet Processing
11.3.1 Sending Packets While Away from Home 11.3.1. Sending Packets While Away from Home
While a mobile node is away from home, it continues to use its home While a mobile node is away from home, it continues to use its home
address, as well as also using one or more care-of addresses. When address, as well as also using one or more care-of addresses. When
sending a packet while away from home, a mobile node MAY choose among sending a packet while away from home, a mobile node MAY choose among
these in selecting the address that it will use as the source of the these in selecting the address that it will use as the source of the
packet, as follows: packet, as follows:
o Protocols layered over IP will generally treat the mobile node's o Protocols layered over IP will generally treat the mobile node's
home address as its IP address for most packets. For packets sent home address as its IP address for most packets. For packets sent
that are part of transport-level connections established while the that are part of transport-level connections established while the
mobile node was at home, the mobile node MUST use its home mobile node was at home, the mobile node MUST use its home
address. Likewise, for packets sent that are part of address. Likewise, for packets sent that are part of transport-
transport-level connections that the mobile node may still be level connections that the mobile node may still be using after
using after moving to a new location, the mobile node SHOULD use moving to a new location, the mobile node SHOULD use its home
its home address in this way. If a binding exists, the mobile address in this way. If a binding exists, the mobile node SHOULD
node SHOULD send the packets directly to the correspondent node. send the packets directly to the correspondent node. Otherwise,
Otherwise, if a binding does not exist, the mobile node MUST use if a binding does not exist, the mobile node MUST use reverse
reverse tunneling. tunneling.
o The mobile node MAY choose to directly use one of its care-of o The mobile node MAY choose to directly use one of its care-of
addresses as the source of the packet, not requiring the use of a addresses as the source of the packet, not requiring the use of a
Home Address option in the packet. This is particularly useful Home Address option in the packet. This is particularly useful
for short-term communication that may easily be retried if it for short-term communication that may easily be retried if it
fails. Using the mobile node's care-of address as the source for fails. Using the mobile node's care-of address as the source for
such queries will generally have a lower overhead than using the such queries will generally have a lower overhead than using the
mobile node's home address, since no extra options need be used in mobile node's home address, since no extra options need be used in
either the query or its reply. Such packets can be routed either the query or its reply. Such packets can be routed
normally, directly between their source and destination without normally, directly between their source and destination without
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the scope of the peer's address. the scope of the peer's address.
Similarly, the mobile node MUST NOT use the Home Address Similarly, the mobile node MUST NOT use the Home Address
destination option for IPv6 Neighbor Discovery [12] packets. destination option for IPv6 Neighbor Discovery [12] packets.
Detailed operation of these cases is described later in this section Detailed operation of these cases is described later in this section
and also discussed in [31]. and also discussed in [31].
For packets sent by a mobile node while it is at home, no special For packets sent by a mobile node while it is at home, no special
Mobile IPv6 processing is required. Likewise, if the mobile node Mobile IPv6 processing is required. Likewise, if the mobile node
uses any address other than any of its home addresses as the source uses any address other than one of its home addresses as the source
of a packet sent while away from home no special Mobile IPv6 of a packet sent while away from home, no special Mobile IPv6
processing is required. In either case, the packet is simply processing is required. In either case, the packet is simply
addressed and transmitted in the same way as any normal IPv6 packet. addressed and transmitted in the same way as any normal IPv6 packet.
For packets sent by the mobile node sent while away from home using For packets sent by the mobile node sent while away from home using
the mobile node's home address as the source, special Mobile IPv6 the mobile node's home address as the source, special Mobile IPv6
processing of the packet is required. This can be done in the processing of the packet is required. This can be done in the
following two ways: following two ways:
Route Optimization Route Optimization
This manner of delivering packets does not require going through This manner of delivering packets does not require going through the
the home network, and typically will enable faster and more home network, and typically will enable faster and more reliable
reliable transmission. transmission.
The mobile node needs to ensure that there exists a Binding Cache The mobile node needs to ensure that a Binding Cache entry exists for
entry for its home address so that the correspondent node can its home address so that the correspondent node can process the
process the packet (Section 9.3.1 specifies the rules for Home packet (Section 9.3.1 specifies the rules for Home Address
Address Destination Option Processing at a correspondent node). Destination Option Processing at a correspondent node). The mobile
The mobile node SHOULD examine its Binding Update List for an node SHOULD examine its Binding Update List for an entry which
entry which fulfills the following conditions: fulfills the following conditions:
* The Source Address field of the packet being sent is equal to * The Source Address field of the packet being sent is equal to the
the home address in the entry. home address in the entry.
* The Destination Address field of the packet being sent is equal * The Destination Address field of the packet being sent is equal to
to the address of the correspondent node in the entry. the address of the correspondent node in the entry.
* One of the current care-of addresses of the mobile node appears * One of the current care-of addresses of the mobile node appears as
as the care-of address in the entry. the care-of address in the entry.
* The entry indicates that a binding has been successfully * The entry indicates that a binding has been successfully created.
created.
* The remaining lifetime of the binding is greater than zero. * The remaining lifetime of the binding is greater than zero.
When these conditions are met, the mobile node knows that the When these conditions are met, the mobile node knows that the
correspondent node has a suitable Binding Cache entry. correspondent node has a suitable Binding Cache entry.
A mobile node SHOULD arrange to supply the home address in a Home A mobile node SHOULD arrange to supply the home address in a Home
Address option, and MUST set the IPv6 header's Source Address Address option, and MUST set the IPv6 header's Source Address field
field to the care-of address which the mobile node has registered to the care-of address which the mobile node has registered to be
to be used with this correspondent node. The correspondent node used with this correspondent node. The correspondent node will then
will then use the address supplied in the Home Address option to use the address supplied in the Home Address option to serve the
serve the function traditionally done by the Source IP address in function traditionally done by the Source IP address in the IPv6
the IPv6 header. The mobile node's home address is then supplied header. The mobile node's home address is then supplied to higher
to higher protocol layers and applications. protocol layers and applications.
Specifically: Specifically:
* Construct the packet using the mobile node's home address as * Construct the packet using the mobile node's home address as the
the packet's Source Address, in the same way as if the mobile packet's Source Address, in the same way as if the mobile node
node were at home. This includes the calculation of upper were at home. This includes the calculation of upper layer
layer checksums using the home address as the value of the checksums using the home address as the value of the source.
source.
* Insert a Home Address option into the packet, with the Home * Insert a Home Address option into the packet with the Home Address
Address field copied from the original value of the Source field copied from the original value of the Source Address field
Address field in the packet. in the packet.
* Change the Source Address field in the packet's IPv6 header to * Change the Source Address field in the packet's IPv6 header to one
one of the mobile node's care-of addresses. This will of the mobile node's care-of addresses. This will typically be
typically be the mobile node's current primary care-of address, the mobile node's current primary care-of address, but MUST be an
but MUST be an address assigned to the interface on the link address assigned to the interface on the link being used.
being used.
By using the care-of address as the Source Address in the IPv6 By using the care-of address as the Source Address in the IPv6
header, with the mobile node's home address instead in the Home header, with the mobile node's home address instead in the Home
Address option, the packet will be able to safely pass through any Address option, the packet will be able to safely pass through any
router implementing ingress filtering [26]. router implementing ingress filtering [26].
Reverse Tunneling Reverse Tunneling
This is the mechanism which tunnels the packets via the home This is the mechanism which tunnels the packets via the home
agent. It is not as efficient as the above mechanism, but is agent. It is not as efficient as the above mechanism, but is
needed if there is no binding yet with the correspondent node. needed if there is no binding yet with the correspondent node.
This mechanism is used for packets that have the mobile node's This mechanism is used for packets that have the mobile node's
home address as the Source Address in the IPv6 header, or with home address as the Source Address in the IPv6 header, or with
multicast control protocol packets as described in Section 11.3.4. multicast control protocol packets as described in Section 11.3.4.
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* The Source Address in the tunnel packet is the primary care-of * The Source Address in the tunnel packet is the primary care-of
address as registered with the home agent. address as registered with the home agent.
* The Destination Address in the tunnel packet is the home * The Destination Address in the tunnel packet is the home
agent's address. agent's address.
Then, the home agent will pass the encapsulated packet to the Then, the home agent will pass the encapsulated packet to the
correspondent node. correspondent node.
11.3.2 Interaction with Outbound IPsec Processing 11.3.2. Interaction with Outbound IPsec Processing
This section sketches the interaction between outbound Mobile IPv6 This section sketches the interaction between outbound Mobile IPv6
processing and outbound IP Security (IPsec) processing for packets processing and outbound IP Security (IPsec) processing for packets
sent by a mobile node while away from home. Any specific sent by a mobile node while away from home. Any specific
implementation MAY use algorithms and data structures other than implementation MAY use algorithms and data structures other than
those suggested here, but its processing MUST be consistent with the those suggested here, but its processing MUST be consistent with the
effect of the operation described here and with the relevant IPsec effect of the operation described here and with the relevant IPsec
specifications. In the steps described below, it is assumed that specifications. In the steps described below, it is assumed that
IPsec is being used in transport mode [4] and that the mobile node is IPsec is being used in transport mode [4] and that the mobile node is
using its home address as the source for the packet (from the point using its home address as the source for the packet (from the point
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containing a Home Address destination option to exchange the two containing a Home Address destination option to exchange the two
fields of the incoming packet to reach the above situation, fields of the incoming packet to reach the above situation,
simplifying processing for all subsequent packet headers. simplifying processing for all subsequent packet headers.
However, such an exchange is not required, as long as the result However, such an exchange is not required, as long as the result
of the authentication calculation remains the same. of the authentication calculation remains the same.
When an automated key management protocol is used to create new When an automated key management protocol is used to create new
security associations for a peer, it is important to ensure that the security associations for a peer, it is important to ensure that the
peer can send the key management protocol packets to the mobile node. peer can send the key management protocol packets to the mobile node.
This may not be possible if the peer is the home agent of the mobile This may not be possible if the peer is the home agent of the mobile
node, and the purpose of the security associations would be to send a node and the purpose of the security associations would be to send a
Binding Update to the home agent. Packets addressed to the home Binding Update to the home agent. Packets addressed to the home
address of the mobile node cannot be used before the Binding Update address of the mobile node cannot be used before the Binding Update
has been processed. For the default case of using IKE [9] as the has been processed. For the default case of using IKE [9] as the
automated key management protocol, such problems can be avoided by automated key management protocol, such problems can be avoided by
the following requirements when communicating with its home agent: the following requirements when communicating with its home agent:
o When the mobile node is away from home, it MUST use its care-of o When the mobile node is away from home, it MUST use its care-of
address as the Source Address of all packets it sends as part of address as the Source Address of all packets it sends as part of
the key management protocol (without use of Mobile IPv6 for these the key management protocol (without use of Mobile IPv6 for these
packets, as suggested in Section 11.3.1). packets, as suggested in Section 11.3.1).
o In addition, for all security associations bound to the mobile o In addition, for all security associations bound to the mobile
node's home address established by IKE, the mobile node MUST node's home address established by IKE, the mobile node MUST
include an ISAKMP Identification Payload [8] in the IKE exchange, include an ISAKMP Identification Payload [8] in the IKE phase 2
giving the mobile node's home address as the initiator of the exchange, giving the mobile node's home address as the initiator
Security Association [7]. of the Security Association [7].
The Key Management Mobility Capability (K) bit in Binding Updates and The Key Management Mobility Capability (K) bit in Binding Updates and
Acknowledgements can be used avoid the need to rerun IKE upon Acknowledgements can be used to avoid the need to rerun IKE upon
movements. movements.
11.3.3 Receiving Packets While Away from Home 11.3.3. Receiving Packets While Away from Home
While away from home, a mobile node will receive packets addressed to While away from home, a mobile node will receive packets addressed to
its home address, by one of two methods: its home address, by one of two methods:
o Packets sent by a correspondent node that does not have a Binding o Packets sent by a correspondent node, that does not have a Binding
Cache entry for the mobile node, will be sent to the home address, Cache entry for the mobile node, will be sent to the home address,
captured by the home agent and tunneled to the mobile node captured by the home agent and tunneled to the mobile node.
o Packets sent by a correspondent node that has a Binding Cache o Packets sent by a correspondent node that has a Binding Cache
entry for the mobile node that contains the mobile node's current entry for the mobile node that contains the mobile node's current
care-of address, will be sent by the correspondent node using a care-of address, will be sent by the correspondent node using a
type 2 routing header. The packet will be addressed to the mobile type 2 routing header. The packet will be addressed to the mobile
node's care-of address, with the final hop in the routing header node's care-of address, with the final hop in the routing header
directing the packet to the mobile node's home address; the directing the packet to the mobile node's home address; the
processing of this last hop of the routing header is entirely processing of this last hop of the routing header is entirely
internal to the mobile node, since the care-of address and home internal to the mobile node, since the care-of address and home
address are both addresses within the mobile node. address are both addresses within the mobile node.
For packets received by the first method, the mobile node MUST check For packets received by the first method, the mobile node MUST check
that the IPv6 source address of the tunneled packet is the IP address that the IPv6 source address of the tunneled packet is the IP address
of its home agent. In this method the mobile node may also send a of its home agent. In this method, the mobile node may also send a
Binding Update to the original sender of the packet, as described in Binding Update to the original sender of the packet as described in
Section 11.7.2, subject to the rate limiting defined in Section 11.8. Section 11.7.2 and subject to the rate limiting defined in Section
The mobile node MUST also process the received packet in the manner 11.8. The mobile node MUST also process the received packet in the