draft-ietf-mobileip-ipv6-19.txt   draft-ietf-mobileip-ipv6-20.txt 
IETF Mobile IP Working Group David B. Johnson IETF Mobile IP Working Group D. Johnson
INTERNET-DRAFT Rice University Internet-Draft Rice University
Charles E. Perkins Expires: July 21, 2003 C. Perkins
Nokia Research Center Nokia Research Center
Jari Arkko J. Arkko
Ericsson Ericsson
29 Oct 2002 January 20, 2003
Mobility Support in IPv6 Mobility Support in IPv6
<draft-ietf-mobileip-ipv6-19.txt> draft-ietf-mobileip-ipv6-20.txt
Status of This Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC 2026. all provisions of Section 10 of RFC 2026.
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Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document specifies the operation of the IPv6 Internet with This document specifies the operation of the IPv6 Internet with
mobile computers. Each mobile node is always identified by its mobile computers. Each mobile node is always identified by its home
home address, regardless of its current point of attachment to the address, regardless of its current point of attachment to the
Internet. While situated away from its home, a mobile node is also Internet. While situated away from its home, a mobile node is also
associated with a care-of address, which provides information about associated with a care-of address, which provides information about
the mobile node's current location. IPv6 packets addressed to a the mobile node's current location. IPv6 packets addressed to a
mobile node's home address are transparently routed to its care-of mobile node's home address are transparently routed to its care-of
address. The protocol enables IPv6 nodes to cache the binding of address. The protocol enables IPv6 nodes to cache the binding of a
a mobile node's home address with its care-of address, and to then mobile node's home address with its care-of address, and to then send
send any packets destined for the mobile node directly to it at this any packets destined for the mobile node directly to it at this
care-of address. To support this operation, Mobile IPv6 defines a care-of address. To support this operation, Mobile IPv6 defines a
new IPv6 protocol and a new destination option. All IPv6 nodes, new IPv6 protocol and a new destination option. All IPv6 nodes,
whether mobile or stationary can communicate with mobile nodes. whether mobile or stationary can communicate with mobile nodes.
Contents Table of Contents
Status of This Memo i
Abstract i
1. Introduction 1
2. Comparison with Mobile IP for IPv4 2
3. Terminology 3
3.1. General Terms . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Mobile IPv6 Terms . . . . . . . . . . . . . . . . . . . . 5
4. Overview of Mobile IPv6 7
4.1. Basic Operation . . . . . . . . . . . . . . . . . . . . . 7
4.2. New IPv6 Protocol . . . . . . . . . . . . . . . . . . . . 9
4.3. New IPv6 Destination Option . . . . . . . . . . . . . . . 10
4.4. New IPv6 ICMP Messages . . . . . . . . . . . . . . . . . 10
4.5. Conceptual Data Structure Terminology . . . . . . . . . . 11
4.6. Site-Local Addressability . . . . . . . . . . . . . . . . 11
5. Overview of Mobile IPv6 Security 12
5.1. Binding Updates to Home Agents . . . . . . . . . . . . . 12
5.2. Binding Updates to Correspondent Nodes . . . . . . . . . 13
5.2.1. Node Keys . . . . . . . . . . . . . . . . . . . . 13
5.2.2. Nonces . . . . . . . . . . . . . . . . . . . . . 13
5.2.3. Cookies and Tokens . . . . . . . . . . . . . . . 14
5.2.4. Cryptographic Functions . . . . . . . . . . . . . 15
5.2.5. Return Routability Procedure . . . . . . . . . . 15
5.2.6. Authorizing Binding Management Messages . . . . . 19
5.2.7. Updating Node Keys and Nonces . . . . . . . . . . 20
5.2.8. Preventing Replay Attacks . . . . . . . . . . . . 22
5.3. Dynamic Home Agent Address Discovery . . . . . . . . . . 22
5.4. Prefix Discovery . . . . . . . . . . . . . . . . . . . . 22
5.5. Payload Packets . . . . . . . . . . . . . . . . . . . . . 22
6. New IPv6 Protocol, Message Types, and Destination Option 23
6.1. Mobility Header . . . . . . . . . . . . . . . . . . . . . 23
6.1.1. Format . . . . . . . . . . . . . . . . . . . . . 23
6.1.2. Binding Refresh Request Message . . . . . . . . . 25
6.1.3. Home Test Init Message . . . . . . . . . . . . . 26
6.1.4. Care-of Test Init Message . . . . . . . . . . . . 27
6.1.5. Home Test Message . . . . . . . . . . . . . . . . 28
6.1.6. Care-of Test Message . . . . . . . . . . . . . . 29
6.1.7. Binding Update Message . . . . . . . . . . . . . 31
6.1.8. Binding Acknowledgement Message . . . . . . . . . 33
6.1.9. Binding Error Message . . . . . . . . . . . . . . 35
6.2. Mobility Options . . . . . . . . . . . . . . . . . . . . 36
6.2.1. Format . . . . . . . . . . . . . . . . . . . . . 37
6.2.2. Pad1 . . . . . . . . . . . . . . . . . . . . . . 37
6.2.3. PadN . . . . . . . . . . . . . . . . . . . . . . 38
6.2.4. Alternate Care-of Address . . . . . . . . . . . . 38
6.2.5. Nonce Indices . . . . . . . . . . . . . . . . . . 39
6.2.6. Binding Authorization Data . . . . . . . . . . . 39
6.2.7. Binding Refresh Advice . . . . . . . . . . . . . 40
6.3. Home Address Option . . . . . . . . . . . . . . . . . . . 41
6.4. Type 2 Routing Header . . . . . . . . . . . . . . . . . . 43
6.4.1. Format . . . . . . . . . . . . . . . . . . . . . 43
6.5. ICMP Home Agent Address Discovery Request Message . . . . 44
6.6. ICMP Home Agent Address Discovery Reply Message . . . . . 46
6.7. ICMP Mobile Prefix Solicitation Message Format . . . . . 47
6.8. ICMP Mobile Prefix Advertisement Message Format . . . . . 49
7. Modifications to IPv6 Neighbor Discovery 51
7.1. Modified Router Advertisement Message Format . . . . . . 51
7.2. Modified Prefix Information Option Format . . . . . . . . 52
7.3. New Advertisement Interval Option Format . . . . . . . . 54
7.4. New Home Agent Information Option Format . . . . . . . . 55
7.5. Changes to Sending Router Advertisements . . . . . . . . 57
7.6. Changes to Sending Router Solicitations . . . . . . . . . 59
7.7. Changes to Duplicate Address Detection . . . . . . . . . 60
8. Requirements for Types of IPv6 Nodes 60
8.1. All IPv6 Nodes . . . . . . . . . . . . . . . . . . . . . 61
8.2. IPv6 Nodes with Support for Route Optimization . . . . . 61
8.3. All IPv6 Routers . . . . . . . . . . . . . . . . . . . . 62
8.4. IPv6 Home Agents . . . . . . . . . . . . . . . . . . . . 62
8.5. IPv6 Mobile Nodes . . . . . . . . . . . . . . . . . . . . 63
9. Correspondent Node Operation 65
9.1. Conceptual Data Structures . . . . . . . . . . . . . . . 65
9.2. Processing Mobility Headers . . . . . . . . . . . . . . . 66
9.3. Packet Processing . . . . . . . . . . . . . . . . . . . . 66
9.3.1. Receiving Packets with Home Address Destination
Option . . . . . . . . . . . . . . . . . . 66
9.3.2. Sending Packets to a Mobile Node . . . . . . . . 67
9.3.3. Sending Binding Error Messages . . . . . . . . . 68
9.3.4. Receiving ICMP Error Messages . . . . . . . . . . 69
9.4. Return Routability Procedure . . . . . . . . . . . . . . 69
9.4.1. Receiving Home Test Init Messages . . . . . . . . 69
9.4.2. Receiving Care-of Test Init Messages . . . . . . 70
9.4.3. Sending Home Test Messages . . . . . . . . . . . 70
9.4.4. Sending Care-of Test Messages . . . . . . . . . . 70
9.5. Processing Bindings . . . . . . . . . . . . . . . . . . . 70
9.5.1. Receiving Binding Updates . . . . . . . . . . . . 71
9.5.2. Requests to Cache a Binding . . . . . . . . . . . 73
9.5.3. Requests to Delete a Binding . . . . . . . . . . 74
9.5.4. Sending Binding Acknowledgements . . . . . . . . 74
9.5.5. Sending Binding Refresh Requests . . . . . . . . 75
9.6. Cache Replacement Policy . . . . . . . . . . . . . . . . 75
10. Home Agent Operation 76
10.1. Conceptual Data Structures . . . . . . . . . . . . . . . 76
10.2. Processing Mobility Headers . . . . . . . . . . . . . . . 77
10.3. Processing Bindings . . . . . . . . . . . . . . . . . . . 77
10.3.1. Primary Care-of Address Registration . . . . . . 77
10.3.2. Primary Care-of Address De-Registration . . . . . 81
10.4. Packet Processing . . . . . . . . . . . . . . . . . . . . 82
10.4.1. Intercepting Packets for a Mobile Node . . . . . 82
10.4.2. Tunneling Intercepted Packets to a Mobile Node . 83
10.4.3. Handling Reverse Tunneled Packets from a Mobile
Node . . . . . . . . . . . . . . . . . . . 85
10.4.4. Protecting Return Routability Packets . . . . . . 85
10.5. Dynamic Home Agent Address Discovery . . . . . . . . . . 86
10.5.1. Receiving Router Advertisement Messages . . . . . 86
10.6. Sending Prefix Information to the Mobile Node . . . . . . 89
10.6.1. Aggregate List of Home Network Prefixes . . . . . 89
10.6.2. Scheduling Prefix Deliveries to the Mobile Node . 90
10.6.3. Sending Advertisements to the Mobile Node . . . . 92
10.6.4. Lifetimes for Changed Prefixes . . . . . . . . . 92
11. Mobile Node Operation 93
11.1. Conceptual Data Structures . . . . . . . . . . . . . . . 93
11.2. Processing Mobility Headers . . . . . . . . . . . . . . . 94
11.3. Packet Processing . . . . . . . . . . . . . . . . . . . . 95
11.3.1. Sending Packets While Away from Home . . . . . . 95
11.3.2. Interaction with Outbound IPsec Processing . . . 97
11.3.3. Receiving Packets While Away from Home . . . . . 99
11.3.4. Receiving ICMP Error Messages . . . . . . . . . . 100
11.3.5. Routing Multicast Packets . . . . . . . . . . . . 101
11.4. Home Agent and Prefix Management . . . . . . . . . . . . 102
11.4.1. Dynamic Home Agent Address Discovery . . . . . . 102
11.4.2. Sending Mobile Prefix Solicitations . . . . . . . 103
11.4.3. Receiving Mobile Prefix Advertisements . . . . . 104
11.5. Movement . . . . . . . . . . . . . . . . . . . . . . . . 105
11.5.1. Movement Detection . . . . . . . . . . . . . . . 105
11.5.2. Forming New Care-of Addresses . . . . . . . . . . 107
11.5.3. Using Multiple Care-of Addresses . . . . . . . . 109
11.5.4. Returning Home . . . . . . . . . . . . . . . . . 109
11.6. Return Routability Procedure . . . . . . . . . . . . . . 111
11.6.1. Sending Home and Care-of Test Init Messages . . . 111
11.6.2. Receiving Return Routability Messages . . . . . . 112
11.6.3. Protecting Return Routability Packets . . . . . . 113
11.7. Processing Bindings . . . . . . . . . . . . . . . . . . . 114
11.7.1. Sending Binding Updates to the Home Agent . . . . 114
11.7.2. Correspondent Binding Procedure . . . . . . . . . 116
11.7.3. Receiving Binding Acknowledgements . . . . . . . 119
11.7.4. Receiving Binding Refresh Requests . . . . . . . 121
11.7.5. Receiving Binding Error Messages . . . . . . . . 121
11.8. Retransmissions and Rate Limiting . . . . . . . . . . . . 122
12. Protocol Constants 123
13. IANA Considerations 124
14. Security Considerations 125
14.1. Threats . . . . . . . . . . . . . . . . . . . . . . . . . 125
14.2. Features . . . . . . . . . . . . . . . . . . . . . . . . 127
14.3. Binding Updates to Home Agent . . . . . . . . . . . . . . 128
14.4. Binding Updates to Correspondent Nodes . . . . . . . . . 130
14.4.1. Overview . . . . . . . . . . . . . . . . . . . . 130
14.4.2. Offered Protection . . . . . . . . . . . . . . . 131
14.4.3. Comparison to Regular IPv6 Communications . . . . 131
14.4.4. Return Routability Replays . . . . . . . . . . . 133
14.4.5. Return Routability Denial-of-Service . . . . . . 133
14.5. Dynamic Home Agent Address Discovery . . . . . . . . . . 134
14.6. Prefix Discovery . . . . . . . . . . . . . . . . . . . . 135
14.7. Tunneling via the Home Agent . . . . . . . . . . . . . . 135
14.8. Home Address Option . . . . . . . . . . . . . . . . . . . 135
14.9. Type 2 Routing Header . . . . . . . . . . . . . . . . . . 136
Contributors 137
Acknowledgements 137
References 139
A. Changes from Previous Version of the Draft 142
A.1. Changes from Draft Version 18 . . . . . . . . . . . . . . 142
B. Future Extensions 146
B.1. Piggybacking . . . . . . . . . . . . . . . . . . . . . . 146
B.2. Triangular Routing and Unverified Home Addresses . . . . 146
B.3. New Authorization Methods beyond Return Routability . . . 146
B.4. Security and Dynamically Generated Home Addresses . . . . 147
B.5. Remote Home Address Configuration . . . . . . . . . . . . 147
Chairs' Addresses 149
Authors' Addresses 149 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 6
2. Comparison with Mobile IP for IPv4 . . . . . . . . . . . . 8
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 10
3.1 General Terms . . . . . . . . . . . . . . . . . . . 10
3.2 Mobile IPv6 Terms . . . . . . . . . . . . . . . . . 12
4. Overview of Mobile IPv6 . . . . . . . . . . . . . . . . . 16
4.1 Basic Operation . . . . . . . . . . . . . . . . . . 16
4.2 New IPv6 Protocol . . . . . . . . . . . . . . . . . 18
4.3 New IPv6 Destination Option . . . . . . . . . . . . 19
4.4 New IPv6 ICMP Messages . . . . . . . . . . . . . . . 19
4.5 Conceptual Data Structure Terminology . . . . . . . 19
4.6 Site-Local Addressability . . . . . . . . . . . . . 20
5. Overview of Mobile IPv6 Security . . . . . . . . . . . . . 21
5.1 Binding Updates to Home Agents . . . . . . . . . . . 21
5.2 Binding Updates to Correspondent Nodes . . . . . . . 22
5.2.1 Node Keys . . . . . . . . . . . . . . . . . 23
5.2.2 Nonces . . . . . . . . . . . . . . . . . . . 23
5.2.3 Cookies and Tokens . . . . . . . . . . . . . 24
5.2.4 Cryptographic Functions . . . . . . . . . . 24
5.2.5 Return Routability Procedure . . . . . . . . 24
5.2.6 Authorizing Binding Management Messages . . 28
5.2.7 Updating Node Keys and Nonces . . . . . . . 30
5.2.8 Preventing Replay Attacks . . . . . . . . . 32
5.3 Dynamic Home Agent Address Discovery . . . . . . . . 32
5.4 Prefix Discovery . . . . . . . . . . . . . . . . . . 32
5.5 Payload Packets . . . . . . . . . . . . . . . . . . 32
6. New IPv6 Protocol, Message Types, and Destination Option . 34
6.1 Mobility Header . . . . . . . . . . . . . . . . . . 34
6.1.1 Format . . . . . . . . . . . . . . . . . . . 34
6.1.2 Binding Refresh Request Message . . . . . . 36
6.1.3 Home Test Init Message . . . . . . . . . . . 37
6.1.4 Care-of Test Init Message . . . . . . . . . 38
6.1.5 Home Test Message . . . . . . . . . . . . . 39
6.1.6 Care-of Test Message . . . . . . . . . . . . 40
6.1.7 Binding Update Message . . . . . . . . . . . 41
6.1.8 Binding Acknowledgement Message . . . . . . 43
6.1.9 Binding Error Message . . . . . . . . . . . 46
6.2 Mobility Options . . . . . . . . . . . . . . . . . . 47
6.2.1 Format . . . . . . . . . . . . . . . . . . . 47
6.2.2 Pad1 . . . . . . . . . . . . . . . . . . . . 48
6.2.3 PadN . . . . . . . . . . . . . . . . . . . . 49
6.2.4 Binding Refresh Advice . . . . . . . . . . . 49
6.2.5 Alternate Care-of Address . . . . . . . . . 49
6.2.6 Nonce Indices . . . . . . . . . . . . . . . 50
6.2.7 Binding Authorization Data . . . . . . . . . 50
6.3 Home Address Option . . . . . . . . . . . . . . . . 52
6.4 Type 2 Routing Header . . . . . . . . . . . . . . . 53
6.4.1 Format . . . . . . . . . . . . . . . . . . . 54
6.5 ICMP Home Agent Address Discovery Request Message . 55
6.6 ICMP Home Agent Address Discovery Reply Message . . 56
6.7 ICMP Mobile Prefix Solicitation Message Format . . . 58
6.8 ICMP Mobile Prefix Advertisement Message Format . . 59
7. Modifications to IPv6 Neighbor Discovery . . . . . . . . . 62
7.1 Modified Router Advertisement Message Format . . . . 62
7.2 Modified Prefix Information Option Format . . . . . 62
7.3 New Advertisement Interval Option Format . . . . . . 64
7.4 New Home Agent Information Option Format . . . . . . 65
7.5 Modified Neighbor Solicitation Message Format . . . 66
7.6 Changes to Sending Router Advertisements . . . . . . 68
7.7 Changes to Duplicate Address Detection . . . . . . . 69
8. Requirements for Types of IPv6 Nodes . . . . . . . . . . . 71
8.1 All IPv6 Nodes . . . . . . . . . . . . . . . . . . . 71
8.2 IPv6 Nodes with Support for Route Optimization . . . 71
8.3 All IPv6 Routers . . . . . . . . . . . . . . . . . . 73
8.4 IPv6 Home Agents . . . . . . . . . . . . . . . . . . 73
8.5 IPv6 Mobile Nodes . . . . . . . . . . . . . . . . . 75
9. Correspondent Node Operation . . . . . . . . . . . . . . . 77
9.1 Conceptual Data Structures . . . . . . . . . . . . . 77
9.2 Processing Mobility Headers . . . . . . . . . . . . 78
9.3 Packet Processing . . . . . . . . . . . . . . . . . 78
9.3.1 Receiving Packets with Home Address Option . 78
9.3.2 Sending Packets to a Mobile Node . . . . . . 79
9.3.3 Sending Binding Error Messages . . . . . . . 81
9.3.4 Receiving ICMP Error Messages . . . . . . . 81
9.4 Return Routability Procedure . . . . . . . . . . . . 81
9.4.1 Receiving Home Test Init Messages . . . . . 82
9.4.2 Receiving Care-of Test Init Messages . . . . 82
9.4.3 Sending Home Test Messages . . . . . . . . . 82
9.4.4 Sending Care-of Test Messages . . . . . . . 83
9.5 Processing Bindings . . . . . . . . . . . . . . . . 83
9.5.1 Receiving Binding Updates . . . . . . . . . 83
9.5.2 Requests to Cache a Binding . . . . . . . . 85
9.5.3 Requests to Delete a Binding . . . . . . . . 86
9.5.4 Sending Binding Acknowledgements . . . . . . 86
9.5.5 Sending Binding Refresh Requests . . . . . . 87
9.6 Cache Replacement Policy . . . . . . . . . . . . . . 88
10. Home Agent Operation . . . . . . . . . . . . . . . . . . . 89
10.1 Conceptual Data Structures . . . . . . . . . . . . . 89
10.2 Processing Mobility Headers . . . . . . . . . . . . 90
10.3 Processing Bindings . . . . . . . . . . . . . . . . 90
10.3.1 Primary Care-of Address Registration . . . . 90
10.3.2 Primary Care-of Address De-Registration . . 93
10.4 Packet Processing . . . . . . . . . . . . . . . . . 94
10.4.1 Intercepting Packets for a Mobile Node . . . 94
10.4.2 Tunneling Intercepted Packets . . . . . . . 96
10.4.3 Multicast Membership Control . . . . . . . . 97
10.4.4 Stateful Address Autoconfiguration . . . . . 98
10.4.5 Handling Reverse Tunneled Packets . . . . . 99
10.4.6 Protecting Return Routability Packets . . . 99
10.5 Dynamic Home Agent Address Discovery . . . . . . . .100
10.5.1 Receiving Router Advertisement Messages . . 100
10.6 Sending Prefix Information to the Mobile Node . . .102
10.6.1 Aggregate List of Home Network Prefixes . . 103
10.6.2 Scheduling Prefix Deliveries . . . . . . . . 104
10.6.3 Sending Advertisements . . . . . . . . . . . 106
10.6.4 Lifetimes for Changed Prefixes . . . . . . . 107
11. Mobile Node Operation . . . . . . . . . . . . . . . . . . 108
11.1 Conceptual Data Structures . . . . . . . . . . . . .108
11.2 Processing Mobility Headers . . . . . . . . . . . .109
11.3 Packet Processing . . . . . . . . . . . . . . . . .110
11.3.1 Sending Packets While Away from Home . . . . 110
11.3.2 Interaction with Outbound IPsec Processing . 112
11.3.3 Receiving Packets While Away from Home . . . 114
11.3.4 Routing Multicast Packets . . . . . . . . . 115
11.3.5 Receiving ICMP Error Messages . . . . . . . 117
11.3.6 Receiving Binding Error Messages . . . . . . 117
11.4 Home Agent and Prefix Management . . . . . . . . . .118
11.4.1 Dynamic Home Agent Address Discovery . . . . 118
11.4.2 Sending Mobile Prefix Solicitations . . . . 119
11.4.3 Receiving Mobile Prefix Advertisements . . . 120
11.5 Movement . . . . . . . . . . . . . . . . . . . . . .121
11.5.1 Movement Detection . . . . . . . . . . . . . 121
11.5.2 Forming New Care-of Addresses . . . . . . . 123
11.5.3 Using Multiple Care-of Addresses . . . . . . 124
11.5.4 Returning Home . . . . . . . . . . . . . . . 125
11.6 Return Routability Procedure . . . . . . . . . . . .127
11.6.1 Sending Test Init Messages . . . . . . . . . 127
11.6.2 Receiving Test Messages . . . . . . . . . . 128
11.6.3 Protecting Return Routability Packets . . . 129
11.7 Processing Bindings . . . . . . . . . . . . . . . .129
11.7.1 Sending Binding Updates to the Home Agent . 129
11.7.2 Correspondent Binding Procedure . . . . . . 132
11.7.3 Receiving Binding Acknowledgements . . . . . 135
11.7.4 Receiving Binding Refresh Requests . . . . . 137
11.8 Retransmissions and Rate Limiting . . . . . . . . .137
12. Protocol Constants . . . . . . . . . . . . . . . . . . . . 139
13. Protocol Configuration Variables . . . . . . . . . . . . . 140
14. IANA Considerations . . . . . . . . . . . . . . . . . . . 141
15. Security Considerations . . . . . . . . . . . . . . . . . 143
15.1 Threats . . . . . . . . . . . . . . . . . . . . . .143
15.2 Features . . . . . . . . . . . . . . . . . . . . . .145
15.3 Binding Updates to Home Agent . . . . . . . . . . .146
15.4 Binding Updates to Correspondent Nodes . . . . . . .147
15.4.1 Overview . . . . . . . . . . . . . . . . . . 147
15.4.2 Achieved Security Properties . . . . . . . . 148
15.4.3 Comparison to Regular IPv6 Communications . 149
15.4.4 Return Routability Replays . . . . . . . . . 151
15.4.5 Return Routability Denial-of-Service . . . . 151
15.5 Dynamic Home Agent Address Discovery . . . . . . . .152
15.6 Prefix Discovery . . . . . . . . . . . . . . . . . .152
15.7 Tunneling via the Home Agent . . . . . . . . . . . .152
15.8 Home Address Option . . . . . . . . . . . . . . . .153
15.9 Type 2 Routing Header . . . . . . . . . . . . . . .154
16. Contributors . . . . . . . . . . . . . . . . . . . . . . . 155
17. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 156
Normative References . . . . . . . . . . . . . . . . . . . 157
Informative References . . . . . . . . . . . . . . . . . . 159
Authors' Addresses . . . . . . . . . . . . . . . . . . . . 160
A. Changes from Previous Version of the Draft . . . . . . . . 161
B. Future Extensions . . . . . . . . . . . . . . . . . . . . 165
B.1 Piggybacking . . . . . . . . . . . . . . . . . . . .165
B.2 Triangular Routing . . . . . . . . . . . . . . . . .165
B.3 New Authorization Methods . . . . . . . . . . . . .165
B.4 Dynamically Generated Home Addresses . . . . . . . .165
B.5 Remote Home Address Configuration . . . . . . . . .165
Intellectual Property and Copyright Statements . . . . . . 167
1. Introduction 1. Introduction
This document specifies how the IPv6 Internet operates with mobile This document specifies how the IPv6 Internet operates with mobile
computers. Without specific support for mobility in IPv6 [11], computers. Without specific support for mobility in IPv6 [11],
packets destined to a mobile node would not be able to reach it while packets destined to a mobile node would not be able to reach it while
the mobile node is away from its home link. In order to continue the mobile node is away from its home link. In order to continue
communication in spite of its movement, a mobile node could change communication in spite of its movement, a mobile node could change
its IP address each time it moves to a new link, but the mobile its IP address each time it moves to a new link, but the mobile node
node would then not be able to maintain transport and higher-layer would then not be able to maintain transport and higher-layer
connections when it changes location. Mobility support in IPv6 is connections when it changes location. Mobility support in IPv6 is
particularly important, as mobile computers are likely to account for particularly important, as mobile computers are likely to account for
a majority or at least a substantial fraction of the population of a majority or at least a substantial fraction of the population of
the Internet during the lifetime of IPv6. the Internet during the lifetime of IPv6.
The protocol defined in this document, known as Mobile IPv6, allows The protocol defined in this document, known as Mobile IPv6, allows a
a mobile node to move from one link to another without changing the mobile node to move from one link to another without changing the
mobile node's "home address". Packets may be routed to the mobile mobile node's "home address". Packets may be routed to the mobile
node using this address regardless of the mobile node's current point node using this address regardless of the mobile node's current point
of attachment to the Internet. The mobile node may also continue of attachment to the Internet. The mobile node may also continue to
to communicate with other nodes (stationary or mobile) after moving communicate with other nodes (stationary or mobile) after moving to a
to a new link. The movement of a mobile node away from its home new link. The movement of a mobile node away from its home link is
link is 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-layer mobility management problem. Some mobility management network-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 Mobile IPv6 does not attempt to solve all general problems related to
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:
- Handling links with partial reachability, or unidirectional o Handling links with partial reachability, or unidirectional
connectivity, such as are often found in wireless networks (but connectivity, such as are often found in wireless networks (but
see Section 11.5.1). see Section 11.5.1).
- Access control on a link being visited by a mobile node. o Access control on a link being visited by a mobile node.
- 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).
- Assistance for adaptive applications o Assistance for adaptive applications
- Mobile routers o Mobile routers
- Service Discovery o Service Discovery
- Distinguishing between packets lost due to bit errors vs. o Distinguishing between packets lost due to bit errors vs. network
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) [20, 21, 22], and from the opportunities in IPv4 (Mobile IPv4) [23, 24, 25], and from the opportunities
provided by IPv6. Mobile IPv6 thus shares many features with provided by IPv6. Mobile IPv6 thus shares many features with Mobile
Mobile IPv4, but is integrated into IPv6 and offers many other IPv4, but is integrated into IPv6 and offers many other improvements.
improvements. This section summarizes the major differences between This section summarizes the major differences between Mobile IPv4 and
Mobile IPv4 and Mobile IPv6: Mobile IPv6:
- There is no need to deploy special routers as "foreign agents", o There is no need to deploy special routers as "foreign agents", as
as in Mobile IPv4. Mobile IPv6 operates in any location without in Mobile IPv4. Mobile IPv6 operates in any location without any
any special support required from the local router. special support required from the local router.
- Support for route optimization is a fundamental part of the o Support for route optimization is a fundamental part of the
protocol, rather than a nonstandard set of extensions. protocol, rather than a nonstandard set of extensions.
- Mobile IPv6 route optimization can operate securely even without o Mobile IPv6 route optimization can operate securely even without
pre-arranged security associations. It is expected that route pre-arranged security associations. It is expected that route
optimization can be deployed on a global scale between all mobile optimization can be deployed on a global scale between all mobile
nodes and correspondent nodes. nodes and correspondent nodes.
- Support is also integrated into Mobile IPv6 for allowing route o Support is also integrated into Mobile IPv6 for allowing route
optimization to coexist efficiently with routers that perform optimization to coexist efficiently with routers that perform
"ingress filtering" [23]. "ingress filtering" [27].
- In Mobile IPv6, the mobile node does not have to tunnel multicast o In Mobile IPv6, the mobile node does not have to tunnel multicast
packets to its home agent. packets to its home agent.
- The movement detection mechanism in Mobile IPv6 provides o The movement detection mechanism in Mobile IPv6 provides
bidirectional confirmation of a mobile node's ability to bidirectional confirmation of a mobile node's ability to
communicate with its default router in its current location. communicate with its default router in its current location.
- Most packets sent to a mobile node while away from home in o Most packets sent to a mobile node while away from home in Mobile
Mobile IPv6 are sent using an IPv6 routing header rather than IP IPv6 are sent using an IPv6 routing header rather than IP
encapsulation, reducing the amount of resulting overhead compared encapsulation, reducing the amount of resulting overhead compared
to Mobile IPv4. to Mobile IPv4.
- Mobile IPv6 is decoupled from any particular link layer, as it o Mobile IPv6 is decoupled from any particular link layer, as it
uses IPv6 Neighbor Discovery [12] instead of ARP. This also uses IPv6 Neighbor Discovery [12] instead of ARP. This also
improves the robustness of the protocol. improves the robustness of the protocol.
- The use of IPv6 encapsulation (and the routing header) removes o The use of IPv6 encapsulation (and the routing header) removes the
the need in Mobile IPv6 to manage "tunnel soft state". need in Mobile IPv6 to manage "tunnel soft state".
- 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 returns a single reply to the mobile node. The directed broadcast
broadcast approach used in IPv4 returns separate replies from approach used in IPv4 returns separate replies from each home
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 RFC 2119 [2].
3.1. General Terms 3.1 General Terms
IP Internet Protocol Version 6 (IPv6). IP
node A device that implements IP. Internet Protocol Version 6 (IPv6).
router A node that forwards IP packets not explicitly node
addressed to itself.
A device that implements IP.
router
A node that forwards IP packets not explicitly addressed to
itself.
unicast routable address unicast routable address
An identifier for a single interface such that
a packet sent to it from another IPv6 subnet is
delivered to the interface identified by that
address. Accordingly, a unicast routable address must
have either a global or site-local scope (but not
link-local).
host Any node that is not a router. An identifier for a single interface such that a packet sent to it
from another IPv6 subnet is delivered to the interface identified
by that address. Accordingly, a unicast routable address must
have either a global or site-local scope (but not link-local).
link A communication facility or medium over which nodes host
can communicate at the link layer, such as an Ethernet
(simple or bridged). A link is the layer immediately
below IP.
interface A node's attachment to a link. Any node that is not a router.
link
A communication facility or medium over which nodes can
communicate at the link layer, such as an Ethernet (simple or
bridged). A link is the layer immediately below IP.
interface
A node's attachment to a link.
subnet prefix subnet prefix
A bit string that consists of some number of initial
bits of an IP address. A bit string that consists of some number of initial bits of an IP
address.
interface identifier interface identifier
A number used to identify a node's interface on a
link. The interface identifier is the remaining A number used to identify a node's interface on a link. The
low-order bits in the node's IP address after the interface identifier is the remaining low-order bits in the node's
subnet prefix. IP address after the subnet prefix.
link-layer address link-layer address
A link-layer identifier for an interface, such as
IEEE 802 addresses on Ethernet links.
packet An IP header plus payload. A link-layer identifier for an interface, such as IEEE 802
addresses on Ethernet links.
packet
An IP header plus payload.
security association security association
A security object shared between two nodes which
includes the data mutually agreed on for operation of An IPsec security association is a simplex "connection" that
some cryptographic algorithm (typically including a affords security services to the traffic carried by it. Security
key). services are afforded to a security association by the use of the
AH and ESP protocols.
security policy database security policy database
A database of rules that describe what security
associations should be applied for different kinds of A database that specifies what security services are to be offered
packets. to IP packets and in what fashion.
destination option destination option
Destination options are carried by the IPv6
Destination Options extension header. Destination Destination options are carried by the IPv6 Destination Options
options include optional information that need extension header. Destination options include optional
be examined only by the IPv6 node given as the information that need be examined only by the IPv6 node given as
destination address in the IPv6 header, not by other the destination address in the IPv6 header, not by other
intermediate routing nodes. Mobile IPv6 defines one intermediate routing nodes. Mobile IPv6 defines one new
new destination option, the Home Address destination destination option, the Home Address destination option (see
option (see Section 6.3). Section 6.3).
routing header routing header
A routing header may be present as an IPv6 header
extension, and indicates that the payload has to be A routing header may be present as an IPv6 header extension, and
delivered to a destination IPv6 address in some way indicates that the payload has to be delivered to a destination
that is different from what would be carried out by IPv6 address in some way that is different from what would be
standard Internet routing. In this document, use of carried out by standard Internet routing. In this document, use
the term "routing header" typically refers to use of a of the term "routing header" typically refers to use of a type 2
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 bytewise concatenation, as in A | B. This Some formulas in this specification use the symbol '|' indicate
concatenation requires that all of the bytes of the bytewise concatenation, as in A | B. This concatenation requires
datum A appear first in the result, followed by all of that all of the bytes of the datum A appear first in the result,
the bytes of the datum B. followed by all of the bytes of the datum B.
First (size, input) First (size, input)
Some formulas in this specification use a functional
form "First (size, input)" to indicate truncation of
the "input" data so that only the first "size" bits
remain to be used.
3.2. Mobile IPv6 Terms Some formulas in this specification use a functional form "First
(size, input)" to indicate truncation of the "input" data so that
only the first "size" bits remain to be used.
3.2 Mobile IPv6 Terms
home address home address
A unicast routable address assigned to a mobile node,
used as the permanent address of the mobile node. This A unicast routable address assigned to a mobile node, used as the
address is within the mobile node's home link. Standard permanent address of the mobile node. This address is within the
IP routing mechanisms will deliver packets destined for mobile node's home link. Standard IP routing mechanisms will
a mobile node's home address to its home link. deliver packets destined for a mobile node's home address to its
home link.
home subnet prefix home subnet prefix
The IP subnet prefix corresponding to a mobile node's
home address.
home link The link on which a mobile node's home subnet prefix is The IP subnet prefix corresponding to a mobile node's home
defined. address.
home link
The link on which a mobile node's home subnet prefix is defined.
mobile node mobile node
A node that can change its point of attachment from one
link to another, while still being reachable via its
home address.
movement A change in a mobile node's point of attachment to the A node that can change its point of attachment from one link to
Internet such that it is no longer connected to the same another, while still being reachable via its home address.
link as it was previously. If a mobile node is not
currently attached to its home link, the mobile node is movement
said to be "away from home".
A change in a mobile node's point of attachment to the Internet
such that it is no longer connected to the same link as it was
previously. If a mobile node is not currently attached to its
home link, the mobile node is said to be "away from home".
correspondent node correspondent node
A peer node with which a mobile node is communicating.
The correspondent node may be either mobile or A peer node with which a mobile node is communicating. The
stationary. correspondent node may be either mobile or stationary.
foreign subnet prefix foreign subnet prefix
Any IP subnet prefix other than the mobile node's home
subnet prefix. Any IP subnet prefix other than the mobile node's home subnet
prefix.
foreign link foreign link
Any link other than the mobile node's home link. Any link other than the mobile node's home link.
care-of address care-of address
A unicast routable address associated with a mobile
node while visiting a foreign link; the subnet prefix A unicast routable address associated with a mobile node while
of this IP address is a foreign subnet prefix. Among visiting a foreign link; the subnet prefix of this IP address is a
the multiple care-of addresses that a mobile node may foreign subnet prefix. Among the multiple care-of addresses that
have at any given time (e.g., with different subnet a mobile node may have at any given time (e.g., with different
prefixes), the one registered with the mobile node's subnet prefixes), the one registered with the mobile node's home
home agent is called its "primary" care-of address. agent is called its "primary" care-of address.
home agent home agent
A router on a mobile node's home link with which the
mobile node has registered its current care-of address. A router on a mobile node's home link with which the mobile node
While the mobile node is away from home, the home agent has registered its current care-of address. While the mobile node
intercepts packets on the home link destined to the is away from home, the home agent intercepts packets on the home
mobile node's home address, encapsulates them, and link destined to the mobile node's home address, encapsulates
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 The association of the home address of a mobile node binding
with a care-of address for that mobile node, along with
the remaining lifetime of that association. The association of the home address of a mobile node with a
care-of address for that mobile node, along with the remaining
lifetime of that association.
registration registration
The process during which a mobile node sends a Binding
Update to its home agent or a correspondent node, The process during which a mobile node sends a Binding Update to
causing a binding for the mobile node to be registered. its home agent or a correspondent node, causing a binding for the
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).
binding procedure binding procedure
A binding procedure is initiated by the mobile node to
inform either a correspondent node or the mobile node's A binding procedure is initiated by the mobile node to inform
home agent of the current binding of the mobile node. either a correspondent node or the mobile node's home agent of the
current binding of the mobile node.
binding authorization binding authorization
Binding procedure needs to be authorized to allow the
recipient to believe that the sender has the right to Binding procedure needs to be authorized to allow the recipient to
specify a new binding. believe that the sender has the right to specify a new binding.
return routability procedure return routability procedure
The return routability procedure authorizes binding
procedures by the use of a cryptographic token exchange. The return routability procedure authorizes binding procedures by
the use of a cryptographic token exchange.
correspondent binding procedure correspondent binding procedure
A return routability procedure followed by a
binding procedure, run between the mobile node and a A return routability procedure followed by a binding procedure,
correspondent node. run between the mobile node and a correspondent node.
home binding procedure home binding procedure
A binding procedure between the mobile node and its home
agent, authorized by the use of IPsec.
nonce Nonces are random numbers used internally by the A binding procedure between the mobile node and its home agent,
correspondent node in the creation of keygen tokens authorized by the use of IPsec.
related to the return routability procedure. The nonces
are not specific to a mobile node, and are kept secret nonce
within the correspondent node.
Nonces are random numbers used internally by the correspondent
node in the creation of keygen tokens related to the return
routability procedure. The nonces are not specific to a mobile
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 creating keygen token values, without
revealing the nonces themselves.
cookie A cookie is a random number used by a mobile nodes to A nonce index is used to indicate which nonces have been used when
prevent spoofing by a bogus correspondent node in the creating keygen token values, without revealing the nonces
return routability procedure. themselves.
cookie
A cookie is a random number used by a mobile nodes to prevent
spoofing by a bogus correspondent node in the return routability
procedure.
care-of init cookie care-of init cookie
A cookie sent to the correspondent node in the Care-of
Test Init message, to be returned in the Care-of Test A cookie sent to the correspondent node in the Care-of Test Init
message. message, to be returned in the Care-of Test message.
home init cookie home init cookie
A cookie sent to the correspondent node in the Home Test
Init message, to be returned in the Home Test message. A cookie sent to the correspondent node in the Home Test Init
message, to be returned in the Home Test message.
keygen token keygen token
A keygen token is a number supplied by a correspondent
node in the return routability procedure to enable the A keygen token is a number supplied by a correspondent node in the
mobile node to compute the necessary binding management return routability procedure to enable the mobile node to compute
key for authorizing a Binding Update. the necessary binding management key for authorizing a Binding
Update.
care-of keygen token care-of keygen token
A keygen token sent by the correspondent node in the
Care-of Test message. A keygen token sent by the correspondent node in the Care-of Test
message.
home keygen token home keygen token
A keygen token sent by the correspondent node in the
Home Test message. A keygen token sent by the correspondent node in the Home Test
message.
binding management key (Kbm) binding management key (Kbm)
A binding management key (Kbm) is a key used for
authorizing a binding cache management message (e.g., A binding management key (Kbm) is a key used for authorizing a
Binding Update or Binding Acknowledgement). Return binding cache management message (e.g., Binding Update or Binding
routability provides a way to create a binding Acknowledgement). Return routability provides a way to create a
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 address, whether it is currently attached to its home link or is away
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 mobile node within its home subnet prefix on its home link. While a
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,
it is also addressable at one or more care-of addresses. A care-of it is also addressable at one or more care-of addresses. A care-of
address is an IP address associated with a mobile node that has the address is an IP address associated with a mobile node that has the
subnet prefix of a particular foreign link. The mobile node can subnet prefix of a particular foreign link. The mobile node can
acquire its care-of address through conventional IPv6 stateless or acquire its care-of address through conventional IPv6 stateless or
stateful auto-configuration mechanisms. As long as the mobile node stateful auto-configuration mechanisms. As long as the mobile node
stays in this location, packets addressed to this care-of address stays in this location, packets addressed to this care-of address
will be routed to the mobile node. The mobile node may also accept will be routed to the mobile node. The mobile node may also accept
packets from several care-of addresses, such as when it is moving but packets from several care-of addresses, such as when it is moving but
still reachable at the previous link. still reachable at the previous link.
The association between a mobile node's home address and care-of The association between a mobile node's home address and care-of
address is known as a "binding" for the mobile node. While away address is known as a "binding" for the mobile node. While away from
from home, a mobile node registers its primary care-of address with home, a mobile node registers its primary care-of address with a
a router on its home link, requesting this router to function as the router on its home link, requesting this router to function as the
"home agent" for the mobile node. The mobile node performs this "home agent" for the mobile node. The mobile node performs this
binding registration by sending a "Binding Update" message to the binding registration by sending a "Binding Update" message to the
home agent. The home agent replies to the mobile node by returning a home agent. The home agent replies to the mobile node by returning a
"Binding Acknowledgement" message. The operation of the mobile node "Binding Acknowledgement" message. The operation of the mobile node
and the home agent is specified in Sections 11 and 10, respectively. is specified in Section 11, and the operation of the home agent is
specified in Section 10.
Any node communicating with a mobile node is referred to in this Any node communicating with a mobile node is referred to in this
document as a "correspondent node" of the mobile node, and may itself document as a "correspondent node" of the mobile node, and may itself
be either a stationary node or a mobile node. Mobile nodes can be either a stationary node or a mobile node. Mobile nodes can
provide information about their current location to correspondent provide information about their current location to correspondent
nodes. This happens through the correspondent binding procedure. As nodes. This happens through the correspondent binding procedure. As
a part of this procedure, a return routability test is performed in a part of this procedure, a return routability test is performed in
order to authorize the establishment of the binding. The operation order to authorize the establishment of the binding. The operation
of the correspondent node is specified in Section 9. of the correspondent node is specified in Section 9.
There are two possible modes for communications between the mobile There are two possible modes for communications between the mobile
node and a correspondent node. The first mode, bidirectional node and a correspondent node. The first mode, bidirectional
tunneling, does not require Mobile IPv6 support from the tunneling, does not require Mobile IPv6 support from the
correspondent node and is available even if the mobile node has not correspondent node and is available even if the mobile node has not
registered its current binding with the correspondent node. Packets registered its current binding with the correspondent node. Packets
from the correspondent node are routed to the home agent and then from the correspondent node are routed to the home agent and then
tunneled to the mobile node. Packets to the correspondent node are tunneled to the mobile node. Packets to the correspondent node are
tunneled from the mobile node to the home agent ("reverse tunneled") tunneled from the mobile node to the home agent ("reverse tunneled")
and then routed normally from the home network to the correspondent and then routed normally from the home network to the correspondent
node. In this mode, the home agent uses proxy Neighbor Discovery node. In this mode, the home agent uses proxy Neighbor Discovery to
to intercept any IPv6 packets addressed to the mobile node's home intercept any IPv6 packets addressed to the mobile node's home
address (or home addresses) on the home link. Each intercepted address (or home addresses) on the home link. Each intercepted
packet is tunneled to the mobile node's primary care-of address. packet is tunneled to the mobile node's primary care-of address.
This tunneling is performed using IPv6 encapsulation [15]. This tunneling is performed using IPv6 encapsulation [15].
The second mode, "route optimization", requires the mobile node to The second mode, "route optimization", requires the mobile node to
register its current binding at the correspondent node. Packets register its current binding at the correspondent node. Packets from
from the correspondent node can be routed directly to the care-of the correspondent node can be routed directly to the care-of address
address of the mobile node. When sending a packet to any IPv6 of the mobile node. When sending a packet to any IPv6 destination,
destination, the correspondent node checks its cached bindings for the correspondent node checks its cached bindings for an entry for
an entry for the packet's destination address. If a cached binding the packet's destination address. If a cached binding for this
for this destination address is found, the node uses a new type of destination address is found, the node uses a new type of IPv6
IPv6 routing header [11] (see Section 6.4) to route the packet to the routing header [11] (see Section 6.4) to route the packet to the
mobile node by way of the care-of address indicated in this binding. mobile node by way of the care-of address indicated in this binding.
Routing packets directly to the mobile node's care-of address allows Routing packets directly to the mobile node's care-of address allows
the shortest communications path to be used. It also eliminates the shortest communications path to be used. It also eliminates
congestion at the mobile node's home agent and home link. In congestion at the mobile node's home agent and home link. In
addition, the impact of any possible failure of the home agent or addition, the impact of any possible failure of the home agent or
networks on the path to or from it is reduced. networks on the path to or from it is reduced.
When routing packets directly to the mobile node, the correspondent When routing packets directly to the mobile node, the correspondent
node sets the Destination Address in the IPv6 header to the care-of node sets the Destination Address in the IPv6 header to the care-of
address of the mobile node. A new type of IPv6 routing header (see address of the mobile node. A new type of IPv6 routing header (see
Section 6.4) is also added to the packet to carry the desired home Section 6.4) is also added to the packet to carry the desired home
address. Similarly, the mobile node sets the Source Address in address. Similarly, the mobile node sets the Source Address in the
the packet's IPv6 header to its current care-of addresses. The packet's IPv6 header to its current care-of addresses. The mobile
mobile node adds a new IPv6 "Home Address" destination option (see node adds a new IPv6 "Home Address" destination option (see Section
Section 6.3) to carry its home address. The inclusion of home 6.3) to carry its home address. The inclusion of home addresses in
addresses in these packets makes the use of the care-of address these packets makes the use of the care-of address transparent above
transparent above the network layer (e.g., at the transport layer). the network layer (e.g., at the transport layer).
Mobile IPv6 also provides support for multiple home agents, and the Mobile IPv6 also provides support for multiple home agents, and the
reconfiguration of the home network. In these cases, the mobile reconfiguration of the home network. In these cases, the mobile node
node may not know the IP address of its own home agent, and even may not know the IP address of its own home agent, and even the home
the home subnet prefixes may change over time. A mechanism, known subnet prefixes may change over time. A mechanism, known as "dynamic
as "dynamic home agent address discovery" allows a mobile node to home agent address discovery" allows a mobile node to dynamically
dynamically discover the IP address of a home agent on its home link, discover the IP address of a home agent on its home link, even when
even when the mobile node is away from home. Mobile nodes can also the mobile node is away from home. Mobile nodes can also learn new
learn new information about home subnet prefixes through the "prefix information about home subnet prefixes through the "prefix discovery"
discovery" mechanism. These mechanisms are described in Sections 6.5 mechanism. These mechanisms are described starting from Section 6.5.
through 6.8.
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
Care-of Test Care-of Test
These four messages are used to initiate the return
routability procedure from the mobile node to a
correspondent node. This ensures authorization of
subsequent Binding Updates, as described in Section 5.2.5.
The format of the messages are defined in Sections 6.1.3 These four messages are used to initiate the return routability
through 6.1.6. procedure from the mobile node to a correspondent node. This
ensures authorization of subsequent Binding Updates, as described
in Section 5.2.5.
Binding Update Binding Update
A Binding Update is used by a mobile node to notify a A Binding Update is used by a mobile node to notify a
correspondent node or the mobile node's home agent of its correspondent node or the mobile node's home agent of its current
current binding. The Binding Update sent to the mobile binding. The Binding Update sent to the mobile node's home agent
node's home agent to register its primary care-of address is to register its primary care-of address is marked as a "home
marked as a "home registration". The Binding Update message registration".
is described in detail in Section 6.1.7.
Binding Acknowledgement Binding Acknowledgement
A Binding Acknowledgement is used to acknowledge receipt of
a Binding Update, if an acknowledgement was requested in the A Binding Acknowledgement is used to acknowledge receipt of a
Binding Update. The Binding Acknowledgement is described in Binding Update, if an acknowledgement was requested in the Binding
detail in Section 6.1.8. Update.
Binding Refresh Request Binding Refresh Request
A Binding Refresh Request is used to request a mobile node
to re-establish its binding with the correspondent node. A Binding Refresh Request is used to request a mobile node to
This message is typically used when the cached binding re-establish its binding with the correspondent node. This
is in active use but the binding's lifetime is close to message is typically used when the cached binding is in active use
expiration. The correspondent node may use, for instance, but the binding's lifetime is close to expiration. The
recent traffic and open transport layer connections as an correspondent node may use, for instance, recent traffic and open
indication of active use. The Binding Refresh Request is transport layer connections as an indication of active use.
described in detail in Section 6.1.2.
Binding Error Binding Error
The Binding Error is used by the correspondent node
to signal an error related to mobility, such as an
inappropriate attempt to use the Home Address destination
option without an existing binding. This message is
described in detail in Section 6.1.9.
4.3. New IPv6 Destination Option The Binding Error is used by the correspondent node to signal an
error related to mobility, such as an inappropriate attempt to use
the Home Address destination option without an existing binding.
Mobile IPv6 defines a new IPv6 destination option, the Home 4.3 New IPv6 Destination Option
Address destination option. This option is described in detail in
Section 6.3.
4.4. New IPv6 ICMP Messages Mobile IPv6 defines a new IPv6 destination option, the Home Address
destination option. This option is described in detail in Section
6.3.
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
Sections 10.5 and 11.4.1, the following two new ICMP message types Section 10.5 and Section 11.4.1, the following two new ICMP message
are used for home agent address discovery: types are used for home agent address discovery:
- Home Agent Address Discovery Request, described in Section 6.5. o Home Agent Address Discovery Request, described in Section 6.5.
- 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 The next two message types are used for network renumbering and
and address configuration on the mobile node, as described in address configuration on the mobile node, as described in Section
Section 10.6: 10.6:
- Mobile Prefix Solicitation, described in Section 6.7. o Mobile Prefix Solicitation, described in Section 6.7.
- 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 A cache of bindings for other nodes. This cache is maintained by
by home agents and correspondent nodes. The cache contains home agents and correspondent nodes. The cache contains both
both "correspondent registration" entries (see Section 9.1) and "correspondent registration" entries (see Section 9.1) and "home
"home registration" entries (see Section 10.1). registration" entries (see Section 10.1).
Binding Update List Binding Update List
This list is maintained by each mobile node. The list has an This list is maintained by each mobile node. The list has an item
item for every binding that the mobile node has or is trying for every binding that the mobile node has or is trying to
to establish with a specific other node. Both correspondent establish with a specific other node. Both correspondent and home
and home registrations are included in this list. Entries from registrations are included in this list. Entries from the list
the list are deleted as the Lifetime sent in the Binding Update are deleted as the Lifetime sent in the Binding Update expires.
expires. See Section 11.1. See Section 11.1.
Home Agents List Home Agents List
Home agents need to know which other home agents are on the Home agents need to know which other home agents are on the same
same link. This information is stored in the Home Agents List, link. This information is stored in the Home Agents List, as
as described in more detail in Section 10.1. The list is used described in more detail in Section 10.1. The list is used for
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
Mobile nodes are free to move from site to site, but the use of
site-local addresses must be carefully managed. When a mobile node
or home agent address is site-local, then packets that use those
address need to stay within the site. The mobile node SHOULD use
such addresses only when it somehow has a guarantee - for instance,
by configuration - that it is safe to do so. Thus, a mobile node MAY
use a site-local home address for roaming within a site, but not for
roaming to another site. This is true even though the mobile node
may be able to obtain a globally addressable care-of address at the
new site.
If a mobile node or home agent has a global IPv6 address available,
it SHOULD be selected for use with Mobile IP signaling, in order to
make the greatest chance for success in case the mobile node might
move to a different site.
Operations affecting multi-sited IPv6 nodes are not completely This specification requires that home and care-of addresses MUST be
understood, especially when mobility management is involved. For unicast routable addresses. Site-local addresses may be usable on
this reason, home agents SHOULD NOT be multi-sited. Similarly, networks that are not connected to the Internet, but this
a mobile node that uses site-local home, care-of, or home agent specification does not define when such usage is safe and when not.
addresses SHOULD NOT be multi-sited. Mobile nodes may not be aware of which site they are currently on, it
is hard to prevent accidental attachment to other sites, and
ambiguity of site-local addresses can cause problems the home and
visited networks use the same addresses. Therefore, site-local
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, and the protection of tunnels, home address correspondent nodes, the protection of prefix discovery, and the
information, and routing instructions in data packets. protection of the mechanisms that Mobile IPv6 uses for 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. through the return routability procedure. Prefix discovery is
protected through the use of IPsec extension headers. Mechanisms
related to transporting payload packets - such as the Home Address
destination option and type 2 routing header - have been specified in
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 have a security association The mobile node and the home agent MUST use an IPsec security
to protect this signaling. Authentication Header (AH) or association to protect the integrity and authenticity of the Binding
Encapsulating Security Payload (ESP) MUST be used. For ESP, a Updates and Acknowledgements. Both the mobile nodes and the home
non-null authentication algorithm MUST be applied. agents SHOULD use the Encapsulating Security Payload (ESP) [6] header
in transport mode and MUST use a non-NULL payload authentication
algorithm to provide data origin authentication, connectionless
integrity and optional anti-replay protection. Note that
Authentication Header (AH) [5] is also possible but for brevity not
discussed in this specification.
In order to protect messages exchanged between the mobile node and In order to protect messages exchanged between the mobile node and
the home agent with IPsec, appropriate security policy database the home agent with IPsec, appropriate security policy database
entries must be created. A mobile node must be prevented from entries must be created. A mobile node must be prevented from using
using its security association to send a Binding Update on behalf its security association to send a Binding Update on behalf of
of another mobile node using the same home agent. This MUST be another mobile node using the same home agent. This MUST be achieved
achieved by checking that the given home address has been used with by having the home agent check that the given home address has been
the right security association. Such a check can be provided in used with the right security association. Such a check is provided
IPsec processing, by having the security policy database entries in the IPsec processing, by having the security policy database
unequivocally identify a single security association for any given entries unequivocally identify a single security association for any
home address and home agent. The check may also be provided as given home address and home agent. In order to make this possible,
a part of Mobile IPv6 processing, if information about the used it is necessary that the home address of the mobile node is visible
security association is available in there. In any case, it is in the Binding Updates and Acknowledgements. The home address is
necessary that the home address of the mobile node is visible in used in these packets as a source or destination, or in the Home
the Binding Updates and Acknowledgements. The home address is used Address Destination option or the type 2 routing header.
in these packets as a source or destination, or in the Home Address
Destination option or 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. Automatic configuration of security associations MUST be supported. The used
key management with IKE [9] MAY be supported. When dynamic keying shared secrets MUST be random and unique for different mobile nodes,
is used, either the security policy database entries or the MIPv6 and MUST be distributed off-line to the mobile nodes.
Automatic key management with IKE [9] MAY be supported. When IKE is
used, either the security policy database entries or the MIPv6
processing MUST unequivocally identify the IKE phase 1 credentials processing MUST unequivocally identify the IKE phase 1 credentials
which can be used to create security associations for a particular which can be used to authorize the creation of security associations
home address. for a particular home address. How these mappings are maintained is
outside the scope of this specification, but they may be maintained,
for instance, as a locally administered table in the home agent. If
the phase 1 identity is a FQDN, secure forms of DNS may also be used.
Reference [24] is an informative description and example of using Section 11.3.2 discusses how IKE connections to the home agent need a
IPsec to protect the communications between the mobile node and the careful treatment of the addresses used for transporting IKE. This
home agent. is necessary to ensure that a Binding Update is not needed before the
IKE exchange which is needed for securing the Binding Update.
5.2. Binding Updates to Correspondent Nodes When IKE version 1 is used with preshared secret authentication
between the mobile node and the home agent, aggressive mode MUST be
used. Similarly, the ID_IPV6_ADDR Identity Payload MUST NOT be used
in IKEv1 phase 1.
Binding Updates to correspondent nodes can be protected by using Reference [21] contains a more detailed description and examples on
a binding management key, Kbm. Kbm may be established using data using IPsec to protect the communications between the mobile node and
exchanged during the return routability procedure. The data exchange the home agent.
is accomplished by use of node keys, nonces, cookies, tokens, and
certain cryptographic functions. Section 5.2.5 outlines the basic
return routability procedure. Section 5.2.6 shows how the results
of this procedure are used to authorize a Binding Update to a
correspondent node. Finally, Sections 5.2.7 and 5.2.8 discuss some
additional issues.
5.2.1. Node Keys 5.2 Binding Updates to Correspondent Nodes
The protection of Binding Updates sent to correspondent nodes does
not require the configuration of security associations or the
existence of an authentication infrastructure between the mobile
nodes and correspondent nodes. Instead, a method called the return
routability procedure is used to assure that the right mobile node is
sending the message. This method does not protect against attackers
who are on the path between the home network and the correspondent
node. However, attacker in such a location are capable of performing
the same attacks even without Mobile IPv6. The main advantage of the
return routability procedure is that it limits the potential
attackers to those having an access to one specific path in the
Internet, and avoids forged Binding Updates from anywhere else in the
Internet. For a more in depth explanation of the security properties
of the return routability procedure, see Section 15.
The integrity and authenticity of the Binding Updates messages to
correspondent nodes are protected by using a keyed-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
return routability procedure. The data exchange is accomplished by
use of node keys, nonces, cookies, tokens, and certain cryptographic
functions. Section 5.2.5 outlines the basic return routability
procedure. Section 5.2.6 shows how the results of this procedure are
used to authorize a Binding Update to a correspondent node.
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; A correspondent node MAY generate a fresh node key at any time; this
this avoid the need for secure persistent key storage. Procedures avoids the need for secure persistent key storage. Procedures for
for optionally updating the node key are discussed later in optionally updating the node key are discussed later in Section
Section 5.2.7. 5.2.7.
5.2.2. Nonces 5.2.2 Nonces
Each correspondent node also generates nonces at regular Each correspondent node also generates nonces at regular intervals.
intervals. The nonces should be generated by using a random number The nonces should be generated by using a random number generator
generator that is known to have good randomness properties [1]. that is known to have good randomness properties [1]. A
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
index, if the nonce index is used as an array pointer into a linear index, if the nonce index is used as an array pointer into a linear
array of nonces. However, there is no requirement that nonces be array of nonces. However, there is no requirement that nonces be
stored that way, or that the values of subsequent nonce indices stored that way, or that the values of subsequent nonce indices have
have any particular relationship to each other. The index value any particular relationship to each other. The index value is
is communicated in the protocol, so that if a nonce is replaced by communicated in the protocol, so that if a nonce is replaced by new
new nonce during the run of a protocol, the correspondent node can nonce during the run of a protocol, the correspondent node can
distinguish messages that should be checked against the old nonce distinguish messages that should be checked against the old nonce
from messages that should be checked against the new nonce. Strictly from messages that should be checked against the new nonce. Strictly
speaking, indices are not necessary in the authentication, but allow speaking, indices are not necessary in the authentication, but allow
the correspondent node to efficiently find the nonce value that it the correspondent node to efficiently find the nonce value that it
used in creating a keygen token. used in creating a keygen token.
Correspondent nodes keep both the current nonce and a small set of Correspondent nodes keep both the current nonce and a small set of
valid previous nonces whose lifetime has not yet expired. Expired valid previous nonces whose lifetime has not yet expired. Expired
values MUST be discarded, and messages using stale or unknown indices values MUST be discarded, and messages using stale or unknown indices
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 determine the validity of the nonce. Expected validity times for the
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.
- The "home init cookie" and "care-of init cookie" are 64 bit o The "home init cookie" and "care-of init cookie" are 64 bit values
values sent to the correspondent node from the mobile node, and sent to the correspondent node from the mobile node, and later
later returned to the mobile node. The home init cookie is sent returned to the mobile node. The home init cookie is sent in the
in the Home Test Init message, and returned in the Home Test Home Test Init message, and returned in the Home Test message.
message. The care-of init cookie is sent in the Care-of Test The care-of init cookie is sent in the Care-of Test Init message,
Init message, and returned in the Care-of Test message. and returned in the Care-of Test message.
- The "home keygen token" and "care-of keygen token" are 64-bit o The "home keygen token" and "care-of keygen token" are 64-bit
values sent by the correspondent node to the mobile node via the values sent by the correspondent node to the mobile node via the
home agent (via the Home Test message) and the care-of address home agent (via the Home Test message) and the care-of address (by
(by the Care-of Test message), respectively. the Care-of Test message), respectively.
The mobile node should use a newly generated random number for each The mobile node should set the home init or care-of init cookie to a
request that carries a home init or care-of init cookie. The cookies newly generated random number in every Home or Care-of Test Init
are used to verify that the Home Test or Care-of Test message matches message it sends. The cookies are used to verify that the Home Test
the Home Test Init or Care-of Test Init message, respectively. These or Care-of Test message matches the Home Test Init or Care-of Test
cookies also serve to ensure that parties who have not seen the Init message, respectively. These cookies also serve to ensure that
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 [19]. Message Authentication Codes (MACs) are computed using SHA1 [20]. Message Authentication Codes (MACs) are computed using
HMAC_SHA1 [25, 19]. HMAC_SHA1(K,m) denotes such a MAC computed on HMAC_SHA1 [26, 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.
Figure 1 shows the message flow for the return routability The below figure shows the message flow for the return routability
procedures. procedure.
The Home and Care-of Test Init messages are sent at the same time.
The procedure requires very little processing at the correspondent
node, and the Home and Care-of Test messages can be returned quickly,
perhaps nearly simultaneously. These four messages form the return
routability procedure.
Home Test Init
A mobile node sends a Home Test Init message to the
correspondent node to acquire the home keygen token. The
contents of the message can be summarized as follows:
Source Address = home address
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) |
|<----------------------------------------------------| |<----------------------------------------------------|
| | | |
Figure 1: Message Flow for Return Routability Address Testing The Home and Care-of Test Init messages are sent at the same time.
The procedure requires very little processing at the correspondent
node, and the Home and Care-of Test messages can be returned quickly,
perhaps nearly simultaneously. These four messages form the return
routability procedure.
Destination Address = correspondent Home Test Init
Parameters:
- home init cookie
The Home Test Init message conveys the mobile node's home A mobile node sends a Home Test Init message to the correspondent
address to the correspondent node. The mobile node also sends node to acquire the home keygen token. The contents of the
along a home init cookie that the correspondent node must message can be summarized as follows:
return later. The Home Test Init message is reverse tunneled
through the home agent. The mobile node remembers these cookie * Source Address = home address
values to obtain some assurance that its protocol messages are
being processed by the desired correspondent node. * Destination Address = correspondent
* Parameters:
+ home init cookie
The Home Test Init message conveys the mobile node's home address
to the correspondent node. The mobile node also sends along a
home init cookie that the correspondent node must return later.
The Home Test Init message is reverse tunneled through the home
agent. (The headers and addresses related to reverse tunneling
have been omitted from the above discussion of the message
contents.) The mobile node remembers these cookie values to obtain
some assurance that its protocol messages are being 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 to acquire the care-of keygen token. The correspondent node to acquire the care-of keygen token. The
contents of this message can be summarized as follows: contents of this message can be summarized as follows:
Source Address = care-of address * Source Address = care-of address
Destination Address = correspondent
Parameters: * Destination Address = correspondent
- care-of init cookie
* Parameters:
+ 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 return later. The Care-of Test Init message is sent directly to
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
message. The contents of the message are: message. The contents of the message are:
Source Address = correspondent * Source Address = correspondent
Destination Address = home address
Parameters:
- home init cookie
- home keygen token
- home nonce index
When the correspondent node receives the Home Test Init * Destination Address = home address
message, it generates a home keygen token as follows:
* Parameters:
+ home init cookie
+ home keygen token
+ home nonce index
When the correspondent node receives the Home Test Init message,
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 where | denotes concatenation. The final "0" inside the HMAC_SHA1
HMAC_SHA1 function is a single zero octet, used to distinguish function is a single zero octet, used to distinguish home and
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 tests
that the mobile can receive messages sent to its home address.
Kcn is used in the production of home keygen token in order to
allow the correspondent node to verify that it generated the home
and care-of nonces, without forcing the correspondent node to
remember a list of all tokens it has handed out. 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 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 the home
agent will have received and authorized the new care-of address
for the mobile node before the return routability procedure. For
improved security, the data passed between the home agent and the
mobile node can be made immune to inspection and passive attacks.
Such protection can be gained by encrypting the home keygen token
as it is tunneled from the home agent to the mobile node as
specified in Section 10.4.6. The security properties of this
additional security are discussed in Section 15.4.1. The home
init cookie from the mobile node is returned in the Home Test
message, to ensure that the message comes from a node on the route
between the home agent and the correspondent node. The home nonce
index is delivered to the mobile node to later allow the
correspondent node to efficiently find the nonce value that it
used in creating the home keygen token.
The home keygen token is formed from the first 64 bits of Care-of Test
the MAC. The home keygen token tests that the mobile can
receive messages sent to its home address. Kcn is used in
the production of home keygen token in order to allow the
correspondent node to verify that it generated the home and
care-of nonces, without forcing the correspondent node to
remember a list of all tokens it has handed out.
The Home Test message is sent to the mobile node via the home This message is sent in response to a Care-of Test Init message.
network, where it is presumed that the home agent will tunnel The contents of the message are:
the 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 the home agent will have received and authorized
the new care-of address for the mobile node before the return
routability procedure. For improved security, it is important
that the data passed between the home agent and the mobile node
be immune from inspection and passive attack. Such protection
can be gained by encrypting the home keygen token as it is
tunneled from the home agent to the mobile node.
The home init cookie from the mobile node is returned in the * Source Address = correspondent
Home Test message, to ensure that the message comes from a node
on the route between the home agent and the correspondent node.
The home nonce index is delivered to the mobile node to later * Destination Address = care-of address
allow the correspondent node to efficiently find the nonce
value that it used in creating the home keygen token.
Care-of Test * Parameters:
This message is sent in response to a Care-of Test Init + care-of init cookie
message. The contents of the message are:
Source Address = correspondent + care-of keygen token
Destination Address = care-of address
Parameters:
- care-of init cookie
- care-of keygen token
- care-of nonce index
The correspondent node sends a challenge also to the mobile's + care-of nonce index
care-of address. When the correspondent node receives the
Care-of Test Init message, it generates a care-of keygen token When the correspondent node receives the Care-of Test Init
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 formed from the first 64 bits of the MAC, and sent directly to the
to the mobile node at its care-of address. The care-of init mobile node at its care-of address. The care-of init cookie from
cookie from the from Care-of Test Init message is returned to the from Care-of Test Init message is returned to ensure that the
ensure that the message comes from a node on the route to the message comes from a node on the route to the correspondent node.
correspondent node. 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 nonce index is provided to identify the nonce used be the same, or different, in the Home and Care-of Test messages.
for 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.
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
skipping to change at page 19, line 8 skipping to change at page 28, line 49
Instead, the binding management key is generated as follows: Instead, the binding management key is generated as 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 it can supply a verifiable Binding Update to the correspondent node.
node. This section provides an overview of this binding procedure. This section provides an overview of this binding procedure. The
Figure 2 shows the message flow. The Binding Update creates a below figure shows the message flow. The Binding Update creates a
binding, and the Binding Acknowledgement is optional. binding, and the Binding Acknowledgement is optional.
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) |
Figure 2: Message Flow for Establishing Binding at
the Correspondent Node
Binding Update Binding Update
To authorize a Binding Update, the mobile node creates a To authorize a Binding Update, the mobile node creates a binding
binding management key Kbm from the keygen tokens as described management key Kbm from the keygen tokens as described in the
in the previous section. The contents of the Binding Update previous section. The contents of the Binding Update include the
include the following: following:
Source Address = care-of address * Source Address = care-of address
Destination Address = correspondent
Parameters:
- home address (within the Home Address destination
option or in the Source Address)
- sequence number (within the Binding Update message
header)
- home nonce index (within the Nonce Indices option)
- care-of nonce index (within the Nonce Indices option)
- HMAC_SHA1 (Kbm, (care-of address | CN address | BU))
The Binding Update may contain a Nonce Indices option, * Destination Address = correspondent
indicating to the correspondent node which home and care-of
nonces to use to recompute Kbm, the binding management key.
The MAC is computed as described in Section 6.2.6, using the * Parameters:
correspondent node's address as the destination address and the
Binding Update message itself as the Mobility Header Data.
Once the correspondent node has verified the MAC, it can create + home address (within the Home Address destination option or
a Binding Cache entry for the mobile. in the Source Address)
+ sequence number (within the Binding Update message header)
+ home nonce index (within the Nonce Indices option)
+ care-of nonce index (within the Nonce Indices option)
+ HMAC_SHA1 (Kbm, (care-of address | CN address | BU))
The Binding Update contains a Nonce Indices option, indicating to
the correspondent node which home and care-of nonces to use to
recompute Kbm, the binding management key. The MAC is computed as
described in Section 6.2.7, using the correspondent node's address
as the destination address and the Binding Update message itself
as the Mobility Header Data. Once the correspondent node has
verified the MAC, it can create a Binding Cache entry for the
mobile.
Binding Acknowledgement Binding Acknowledgement
The Binding Update is optionally acknowledged by the The Binding Update is optionally acknowledged by the correspondent
correspondent node. The contents of the message are as node. The contents of the message are as follows:
follows:
Source Address = correspondent * Source Address = correspondent
Destination Address = care-of address
Parameters:
- sequence number (within the Binding Update message
header)
- HMAC_SHA1 (Kbm, (care-of address | CN address | BA))
The Binding Acknowledgement contains the same sequence number * Destination Address = care-of address
as the Binding Update. The MAC is computed as described in
Section 6.2.6, using the correspondent node's address as the
destination address and the message itself as the Mobility
Header Data.
Bindings established with correspondent nodes using keys created * Parameters:
by way of the return routability procedure MUST NOT exceed
+ sequence number (within the Binding Update message header)
+ HMAC_SHA1 (Kbm, (care-of address | CN address | BA))
The Binding Acknowledgement contains the same sequence number as
the Binding Update. The MAC is computed as described in Section
6.2.7, using the correspondent node's address as the destination
address and the message itself as the Mobility Header Data.
Bindings established with correspondent nodes using keys created by
way of the return routability procedure MUST NOT exceed
MAX_RR_BINDING_LIFE seconds (see Section 12). MAX_RR_BINDING_LIFE 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 the
Binding Update is normally also the care-of address which is used in Binding Update is normally also the care-of address which is used in
the binding. However, a different care-of address MAY be specified the binding. However, a different care-of address MAY be specified
by including an Alternate Care-of Address mobility option in the by including an Alternate Care-of Address mobility option in the
Binding Update (see Section 6.2.4). When such a message is sent to Binding Update (see Section 6.2.5). When such a message is sent to
the correspondent node and the return routability procedure is used the correspondent node and the return routability procedure is used
as the authorization method, the Care-of Test Init and Care-of Test as the authorization method, the Care-of Test Init and Care-of Test
messages MUST have been performed for the address in the Alternate messages MUST have been performed for the address in the Alternate
Care-of Address option (not the Source Address). The nonce indices Care-of Address option (not the Source Address). The nonce indices
and MAC value MUST be based on information gained in this test. and MAC value MUST be based on information gained in this test.
The care-of address may be set equal to the home address in order to Binding Updates may also be sent to delete a previously established
delete a previously established binding In this case, generation of binding. In this case, generation of the binding management key
the binding management key depends exclusively on the home keygen depends exclusively on the home keygen token and the care-of nonce
token (Section 5.2.5). 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 Correspondent nodes generate nonces at regular intervals. It is
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_LIFE seconds (see Section 12) acceptable for at least MAX_TOKEN_LIFE seconds (see Section 12) after
after it has been first used in constructing a return routability it has been first used in constructing a return routability message
message response. However, the correspondent node MUST NOT accept response. However, the correspondent node MUST NOT accept nonces
nonces beyond MAX_NONCE_LIFE seconds (see Section 12) after the first beyond MAX_NONCE_LIFE seconds (see Section 12) after the first use.
use. As the difference between these two constants is 30 seconds, As the difference between these two constants is 30 seconds, a
a convenient way to enforce the above lifetimes is to generate a convenient way to enforce the above lifetimes is to generate a new
new nonce every 30 seconds. The node can then continue to accept nonce every 30 seconds. The node can then continue to accept tokens
tokens that have been based on the last 8 (MAX_NONCE_LIFE / 30) that have been based on the last 8 (MAX_NONCE_LIFE / 30) nonces.
nonces. This results in tokens being acceptable MAX_TOKEN_LIFE This results in tokens being acceptable MAX_TOKEN_LIFE to
to MAX_NONCE_LIFE seconds after they have been sent to the mobile MAX_NONCE_LIFE seconds after they have been sent to the mobile node,
node, depending on whether the token was sent at the beginning or depending on whether the token was sent at the beginning or end of
end of the first 30 second period. Note that the correspondent the first 30 second period. Note that the correspondent node may
node may also attempt to generate new nonces on demand, or only if also attempt to generate new nonces on demand, or only if the old
the old nonces have been used. This is possible, as long as the nonces have been used. This is possible, as long as the
correspondent node keeps track of how long time ago the nonces were correspondent node keeps track of how long a time ago the nonces were
used for the first time, and does not generate new nonces on every used for the first time, and does not generate new nonces on every
return routability request. 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 the correspondent node may not in all cases recognize the nonces that
that the tokens were based on. If a nonce index is unrecognized, the tokens were based on. If a nonce index is unrecognized, the
the correspondent node replies with an an error code in the correspondent node replies with an an error code in the Binding
Binding Acknowledgement (either 136, 137, or 138 as discussed Acknowledgement (either 136, 137, or 138 as discussed in Section
in Section 6.1.8). The mobile node can then retry the return 6.1.8). The mobile node can then retry the return routability
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_LIFE seconds, the mobile node MAY use them beyond a single MAX_TOKEN_LIFE seconds, the mobile node MAY use them beyond a single
run of the return routability procedure until MAX_TOKEN_LIFE expires. run of the return routability procedure until MAX_TOKEN_LIFE expires.
After this the mobile node SHOULD NOT use the tokens. A fast moving After this the mobile node SHOULD NOT use the tokens. A fast moving
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keygen token to show routability in the new location. keygen token to show routability in 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 number and a MAC. Care must be taken when removing bindings at the
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. The correspondent node can, for instance, change the nonce valid. Alternatively, if memory is very constrained, the
often enough to ensure that the nonces used when removed entries correspondent node MAY invalidate the nonces that were used for the
were created are no longer valid. If many such deletions occur binding being deleted (or some larger group of nonces that they
the correspondent node can batch them together to avoid having to belong to). This may, however, impact the ability to accept Binding
increment the nonce index too often. Updates from mobile nodes that have recently received keygen tokens.
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. Prefix Discovery 5.4 Prefix Discovery
The mobile node and the home agent must have a security association The mobile node and the home agent SHOULD use an IPsec security
to protect prefix discovery. IPsec AH or ESP SHOULD be supported and association to protect the integrity and authenticity of the Mobile
used for integrity protection. For ESP, a non-null authentication Prefix Solicitations and Advertisements. Both the mobile nodes and
algorithm MUST be applied. the home agents SHOULD use the Encapsulating Security Payload (ESP)
header in transport mode with a non-NULL payload authentication
algorithm to provide data origin authentication, connectionless
integrity and optional anti-replay 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
Binding Cache entry for the given home address. This avoids the use Binding Cache entry for the given home address. This avoids the use
of the Home Address option in attacks described in Section 14.1. of the Home Address option in attacks described in Section 15.1.
Mobile IPv6 uses a Mobile IPv6 specific type of a routing header. Mobile IPv6 uses a Mobile IPv6 specific type of a routing header.
This type provides the necessary functionality but does not open This type provides the necessary functionality but does not open
vulnerabilities discussed in Section 14.1. vulnerabilities discussed in Section 15.1.
Tunnels between the mobile node and the home agent are protected by Tunnels between the mobile node and the home agent are protected by
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). These node (Binding Updates sent to the home agents are secure). The home
measures protect the tunnels against vulnerabilities discussed in agent identifies the mobile node through the source address of the
Section 14.1. inner packet.(Typically, this is the home address of the mobile 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 agent
requires that the Link-Local Address Compatibility (L) was set in the
Binding Update.) These measures protect the tunnels against
vulnerabilities discussed in Section 15.1.
For traffic tunneled via the home agent, additional IPsec AH or ESP For traffic tunneled via the home agent, additional IPsec ESP
encapsulation MAY be supported and used. encapsulation MAY be supported and used. If multicast group
membership control protocols or stateful address autoconfiguration
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 correspondent nodes, and home agents in all messaging related to the
the creation and management of bindings. The subsections within creation and management of bindings. The subsections within this
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.
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 TBD <To
be assigned by IANA> in the immediately preceding header, and has the be assigned by IANA> in 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 following the Mobility Header. Uses the same values as the IPv6
IPv6 Next Header field [11]. Next Header field [11].
This field is intended to be used by a future specification
of piggybacking binding messages on payload packets (see
Section B.1).
Implementations conforming to this specification SHOULD set the This field is intended to be used by a future specification of
payload protocol type to IPPROTO_NONE (59 decimal). piggybacking binding messages on payload packets (see Appendix
B.1). Implementations conforming to this specification SHOULD set
the payload protocol type to IPPROTO_NONE (59 decimal).
Header Len Header Len
8-bit unsigned integer, representing the length of the Mobility 8-bit unsigned integer, representing the length of the Mobility
Header in units of 8 octets, excluding the first 8 octets. Header in units of 8 octets, excluding the first 8 octets.
The length of the Mobility Header MUST be a multiple of 8 The length of the Mobility Header MUST be a multiple of 8 octets.
octets.
MH Type MH Type
8-bit selector. Identifies the particular mobility message 8-bit selector. Identifies the particular mobility message in
in question. Current values are specified in Sections 6.1.2 question. Current values are specified in Section 6.1.2 and
to 6.1.9. An unrecognized MH Type field causes an error onward. An unrecognized MH Type field causes an error indication
indication to be sent. to be sent.
Reserved Reserved
8-bit field reserved for future use. The value MUST be 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.
Checksum Checksum
16-bit unsigned integer. This field contains the checksum of 16-bit unsigned integer. This field contains the checksum of the
the Mobility Header. The checksum is calculated from the octet Mobility Header. The checksum is calculated from the octet string
string consisting of a "pseudo-header" followed by the entire consisting of a "pseudo-header" followed by the entire Mobility
Mobility Header starting with the Payload Proto field. The Header starting with the Payload Proto field. The checksum is the
checksum is the 16-bit one's complement of the one's complement 16-bit one's complement of the one's complement sum of this
sum of this string. string.
The pseudo-header contains IPv6 header fields, as specified
in Section 8.1 of [11]. The Next Header value used in the
pseudo-header is TBD <To be assigned by IANA>. The addresses
used in the pseudo-header are the addresses that appear in
the Source and Destination Address fields in the IPv6 packet
carrying the Mobility Header.
Note that the procedures described in Section 11.3.1 apply
even for the Mobility Header. If a mobility message has a
Home Address destination option, then the checksum calculation
uses the home address in this option as the value of the IPv6
Source Address field. The type 2 routing header is treated as
explained in [26].
The Mobility Header is considered as the upper layer protocol
for the purposes of calculating the pseudo-header. The
Upper-Layer Packet Length field in the pseudo-header MUST be
set to the total length of the Mobility Header.
For computing the checksum, the checksum field is set to zero. The pseudo-header contains IPv6 header fields, as specified in
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
in the pseudo-header are the addresses that appear in the Source
and Destination Address fields in the IPv6 packet carrying the
Mobility Header. Note that the procedures described in Section
11.3.1 apply even for the Mobility Header. If a mobility message
has a Home Address destination option, then the checksum
calculation uses the home address in this option as the value of
the IPv6 Source Address field. The type 2 routing header is
treated as explained in [22]. The Mobility Header is considered
as the upper layer protocol for the purposes of calculating the
pseudo-header. The Upper-Layer Packet Length field in the
pseudo-header MUST be set to the total length of the Mobility
Header. For computing the checksum, the checksum field is set to
zero.
Message Data Message Data
A variable length field containing the data specific to the A variable length field containing the data specific to the
indicated Mobility Header type. indicated Mobility Header type.
Mobile IPv6 also defines a number of "mobility options" for use Mobile IPv6 also defines a number of "mobility options" for use
within these messages; if included, any options MUST appear after the within these messages; if included, any options MUST appear after the
fixed portion of the message data specified in this document. The fixed portion of the message data specified in this document. The
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 properly, and that the total length of the message is divisible by 8.
by 8. The encoding and format of defined options are described in The encoding and format of defined options are described in Section
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-octet boundary. 8-octet boundary.
6.1.2. Binding Refresh Request Message 6.1.2 Binding Refresh Request Message
The Binding Refresh Request (BRR) message is used to request a The Binding Refresh Request (BRR) message requests a mobile node to
mobile node's binding from the mobile node. It is sent according to update its mobility binding. This message is sent by correspondent
the rules in Section 9.5.5. When a mobile node receives a packet nodes according to the rules in Section 9.5.5. When a mobile node
containing a Binding Refresh Request message it processes the message receives a packet containing a Binding Refresh Request message it
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
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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
Header is an integer multiple of 8 octets long. Contains one Header is an integer multiple of 8 octets long. Contains zero or
or more TLV-encoded mobility options. The encoding and format more TLV-encoded mobility options. The encoding and format of
of defined options are described in Section 6.2. The receiver defined options are described in Section 6.2. The receiver MUST
MUST ignore and skip any options which it does not understand. ignore and skip any options which it does not understand.
There MAY be additional information, associated with this There MAY be additional information, associated with this Binding
Binding Refresh Request message, that need not be present in Refresh Request message, that need not be present in all Binding
all Binding Refresh Request messages sent. Mobility options Refresh Request messages sent. Mobility options allow future
allow future extensions to the format of the Binding Refresh extensions to the format of the Binding Refresh Request message to
Request message to be defined. This specification does not be defined. This specification does not define any options valid
define any options valid for the Binding Refresh Request for the Binding Refresh Request message.
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 |
skipping to change at page 27, line 7 skipping to change at page 37, line 46
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 64-bit field which contains a random value, the home init cookie.
cookie.
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. Contains Header is an integer multiple of 8 octets long. Contains zero or
one or more TLV-encoded mobility options. The receiver MUST more TLV-encoded mobility options. The receiver MUST ignore and
ignore and skip any options which it does not understand. This skip any options which it does not understand. This specification
specification does not define any options valid for the Home does not define any options valid for the Home Test Init message.
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.
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 mode between the home agent and the mobile node. This protection is
is indicated by the IPsec policy data base. The protection of Home indicated by the IPsec policy data base. The protection of Home Test
Test Init messages is unrelated to the requirement to protect regular Init messages is unrelated to the requirement to protect regular
payload traffic, which MAY use such tunnels as well. 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 |
skipping to change at page 28, line 18 skipping to change at page 39, line 8
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
cookie. cookie.
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. Contains Header is an integer multiple of 8 octets long. Contains zero or
one or more TLV-encoded mobility options. The receiver MUST more TLV-encoded mobility options. The receiver MUST ignore and
ignore and skip any options which it does not understand. This skip any options which it does not understand. This specification
specification does not define any options valid for the Care-of does not define any options valid for the Care-of Test Init
Test Init message. 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 Nonce + + 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.
Home Keygen Nonce Home Keygen Token
This field contains the 64 bit home keygen token used in the This field contains the 64 bit home keygen token used in the
return routability procedure. return routability procedure.
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. Contains Header is an integer multiple of 8 octets long. Contains zero or
one or more TLV-encoded mobility options. The receiver MUST more TLV-encoded mobility options. The receiver MUST ignore and
ignore and skip any options which it does not understand. This skip any options which it does not understand. This specification
specification does not define any options valid for the Home 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 The Care-of Test (CoT) message is a response to the Care-of Test Init
Init message, and is sent from the correspondent node to the mobile message, and is sent from the correspondent node to the mobile node
node (see Section 11.6.2). The Care-of Test message uses the MH (see Section 11.6.2). The Care-of Test message uses the MH Type
Type value 4. When this value is indicated in the MH Type field, value 4. When this value is indicated in the MH Type field, the
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 Nonce + + 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.
Care-of Keygen Nonce Care-of Keygen Token
This field contains the 64 bit care-of keygen token used in the This field contains the 64 bit care-of keygen token used in the
return routability procedure. return routability procedure.
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. Contains Header is an integer multiple of 8 octets long. Contains zero or
one or more TLV-encoded mobility options. The receiver MUST more TLV-encoded mobility options. The receiver MUST ignore and
ignore and skip any options which it does not understand. This skip any options which it does not understand. This specification
specification does not define any options valid for the Care-of does not define any options valid for the Care-of 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.
6.1.7. 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 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|S|D|L| 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 request a Binding Acknowledgement (Section 6.1.8) be returned upon
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 The Home Registration (H) bit is set by the sending mobile node to
node to request that the receiving node should act as this request that the receiving node should act as this node's home
node's home agent. The destination of the packet carrying this agent. The destination of the packet carrying this message MUST
message MUST be that of a router sharing the same subnet prefix be that of a router sharing the same subnet prefix as the home
as the home address of the mobile node in the binding. address of the mobile node in the binding.
Single Address Only (S)
If this bit is set, the mobile node requests that the home Link-Local Address Compatibility (L)
agent make no changes to any other Binding Cache entry except
for the particular one containing the home address specified
in the Home Address destination option. This disables home
agent processing for other related addresses, as is described
in Section 10.3.1.
Duplicate Address Detection (D) The Link-Local Address Compatibility (L) bit is set when the home
address reported by the mobile node has the same interface
identifier as the mobile node's link-local address.
The Duplicate Address Detection (D) bit is set by the sending Key Management Mobility Capability (K)
mobile node to request that the receiving node (the mobile
node's home agent) perform Duplicate Address Detection [13]
on the mobile node's home link for the home address in this
binding. This bit is only valid when the Home Registration (H)
and Acknowledge (A) bits are also set, and MUST NOT be set
otherwise.
Link-Local Address Compatibility (L) If this bit is reset, the protocol used for establishing the IPsec
security associations between the mobile node and the home agent
does not survive movements. It may then have to be rerun. (Note
that the IPsec security associations themselves are expected to
survive movements.) If manual IPsec configuration is used, the bit
MUST be set to 1.
The Link-Local Address Compatibility (L) bit is set when the This bit is valid only in Binding Updates sent to the home agent.
home address reported by the mobile node has the same interface Correspondent nodes MUST ignore this bit.
identifier (IID) as the mobile node's link-local address.
Reserved Reserved
These fields are unused. They MUST be initialized to zero by These fields are unused. They MUST be initialized to zero by the
the sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
Sequence # Sequence #
A 16-bit number used by the receiving node to sequence Binding A 16-bit unsigned integer used by the receiving node to sequence
Updates and by the sending node to match a returned Binding Binding Updates and by the sending node to match a returned
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 before the binding MUST be considered expired. A value of all one
all one bits (0xffff) indicates infinity. A value of zero bits (0xffff) indicates infinity. A value of zero indicates that
indicates that the Binding Cache entry for the mobile node MUST the Binding Cache entry for the mobile node MUST be deleted. One
be deleted. One time unit is 4 seconds. 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. Contains one Header is an integer multiple of 8 octets long. Contains one or
or more TLV-encoded mobility options. The encoding and format more TLV-encoded mobility options. The encoding and format of
of defined options are described in Section 6.2. The receiver defined options are described in Section 6.2. The receiver MUST
MUST ignore and skip any options which it does not understand. ignore and skip any options which it does not understand.
The following options are valid in a Binding Update: The following options are valid in a Binding Update:
- Binding Authorization Data option * Binding Authorization Data option
- 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 bytes of padding is If no options are present in this message, 4 bytes of padding is
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 MUST be a unicast routable address. Binding The care-of address MUST be a unicast routable address. Binding
Updates for a care-of address which is not a unicast routable address Updates for a care-of address which is not a unicast routable address
MUST be silently discarded. MUST be silently discarded.
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 or by setting the care-of address equal to the home field to 0 or by setting the care-of address equal to the home
address. In either case, generation of the binding management address. In either case, generation of the binding management key
key depends exclusively on the home keygen token (Section 5.2.5). depends exclusively on the home keygen token (Section 5.2.5).
Correspondent nodes SHOULD NOT expire the Binding Cache entry before Correspondent nodes SHOULD NOT expire 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 deallocated 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 an Binding Error message is sent to the mobile
node (see Section 6.1.9); however, it causes unnecessary delay in the node (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
Sections 9.5.4 and 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 | Reserved | | Status |K| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # | Lifetime | | Sequence # | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. . . .
. Mobility options . . Mobility options .
. . . .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Key Management Mobility Capability (K)
If this bit is reset, the protocol used by the home agent for
establishing the IPsec security associations between the mobile
node and the home agent does not survive movements. It may then
have to be rerun. (Note that the IPsec security associations
themselves are expected to survive movements.)
Correspondent nodes MUST set the K bit to 0.
Reserved Reserved
These fields are unused. They MUST be initialized to zero by These fields are unused. They MUST be initialized to zero by the
the sender and MUST be ignored by the receiver. sender and MUST be ignored by the receiver.
Status Status
8-bit unsigned integer indicating the disposition of the 8-bit unsigned integer indicating the disposition of the Binding
Binding Update. Values of the Status field less than 128 Update. Values of the Status field less than 128 indicate that
indicate that the Binding Update was accepted by the receiving the Binding Update was accepted by the receiving node. Values
node. Values greater than or equal to 128 indicate that greater than or equal to 128 indicate that the Binding Update was
the Binding Update was rejected by the receiving node. The rejected by the receiving node. The following Status values are
following Status values are currently defined: currently defined:
0 Binding Update accepted 0 Binding Update accepted
128 Reason unspecified 128 Reason unspecified
129 Administratively prohibited 129 Administratively prohibited
130 Insufficient resources 130 Insufficient resources
131 Home registration not supported 131 Home registration not supported
132 Not home subnet 132 Not home subnet
133 Not home agent for this mobile node 133 Not home agent for this mobile node
134 Duplicate Address Detection failed 134 Duplicate Address Detection failed
135 Sequence number out of window 135 Sequence number out of window
136 Expired home nonce index 136 Expired home nonce index
137 Expired care-of nonce index 137 Expired care-of nonce index
138 Expired nonces 138 Expired nonces
Up-to-date values of the Status field are to be specified in Up-to-date values of the Status field are to be specified in the
the IANA registry of assigned numbers [18]. IANA registry of assigned numbers [19].
Sequence # Sequence #
The Sequence Number in the Binding Acknowledgement is The Sequence Number in the Binding Acknowledgement is copied from
copied from the Sequence Number field in the Binding Update. the Sequence Number field in the Binding Update. It is used by
It is used by the mobile node in matching this Binding the mobile node in matching this Binding Acknowledgement with an
Acknowledgement with an outstanding Binding Update. outstanding Binding Update.
Lifetime Lifetime
The granted lifetime, in time units of 4 seconds, for which The granted lifetime, in time units of 4 seconds, for which this
this node SHOULD retain the entry for this mobile node in its node SHOULD retain the entry for this mobile node in its Binding
Binding Cache. A value of all one bits (0xffff) indicates Cache. A value of all one bits (0xffff) indicates infinity.
infinity.
The value of this field is undefined if the Status field The value of this field is undefined if the Status field indicates
indicates that the Binding Update was rejected. that the Binding Update was rejected.
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. Contains one Header is an integer multiple of 8 octets long. Contains one or
or more TLV-encoded mobility options. The encoding and format more TLV-encoded mobility options. The encoding and format of
of defined options are described in Section 6.2. The receiver defined options are described in Section 6.2. The receiver MUST
MUST ignore and skip any options which it does not understand. ignore and skip any options which it does not understand.
There MAY be additional information, associated with this There MAY be additional information, associated with this Binding
Binding Acknowledgement, that need not be present in all Acknowledgement, that need not be present in all Binding
Binding Acknowledgements sent. Mobility options allow future Acknowledgements sent. Mobility options allow future extensions
extensions to the format of the Binding Acknowledgement to to the format of the Binding Acknowledgement to be defined. The
be defined. The following options are valid for the Binding following options are valid for the Binding Acknowledgement:
Acknowledgement:
- Binding Authorization Data option * Binding Authorization Data option
- Binding Refresh Advice option * Binding Refresh Advice option
If no options are present in this message, 4 bytes of padding is If no options are present in this message, 4 bytes of padding is
necessary and the Header Len field will be set to 1. necessary and the Header Len field will be set to 1.
6.1.9. 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:
skipping to change at page 36, line 14 skipping to change at page 47, line 10
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
destination option. The mobile node uses this information to destination option. The mobile node uses this information to
determine which binding does not exist, in cases where the determine which binding does not exist, in cases where the mobile
mobile node has several home addresses. node has several home addresses.
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. Contains one Header is an integer multiple of 8 octets long. Contains zero or
or more TLV-encoded mobility options. The receiver MUST ignore more TLV-encoded mobility options. The receiver MUST ignore and
and skip any options which it does not understand. skip any options which it does not understand.
There MAY be additional information, associated with this There MAY be additional information, associated with this Binding
Binding Error message, that need not be present in all Binding Error message, that need not be present in all Binding Error
Error messages sent. Mobility options allow future extensions messages sent. Mobility options allow future extensions to the
to the format of the format of the Binding Error message to format of the format of the Binding Error message to be defined.
be defined. The encoding and format of defined options are The encoding and format of defined options are described in
described in Section 6.2. This specification does not define Section 6.2. This specification does not define any options valid
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 one or more mobility options. This Mobility messages can include one 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 6.2.6) 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 8-bit identifier of the type of mobility option. When processing
processing a Mobility Header containing an option for which a Mobility Header containing an option for which the Option Type
the Option Type value is not recognized by the receiver, value is not recognized by the receiver, the receiver MUST quietly
the receiver MUST quietly ignore and skip over the option, ignore and skip over the option, correctly handling any remaining
correctly handling any remaining options in the message. options in the message.
Option Length Option Length
8-bit unsigned integer, representing the length in octets of 8-bit unsigned integer, representing the length in octets of the
the mobility option, not including the Option Type and Option mobility option, not including the Option Type and Option Length
Length fields. fields.
Option Data Option Data
A variable length field that contains data specific to the A variable length field that contains data specific to the option.
option.
The following subsections specify the Option types which are The following subsections specify the Option types which are
currently defined for use in the Mobility Header. currently defined for use in the Mobility Header.
Implementations MUST silently ignore any mobility options that they Implementations MUST silently ignore any mobility options that they
do not understand. do not understand.
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. Option data MUST be Option Data consists of N-2 zero-valued octets. PadN Option data
ignored by the receiver. MUST be ignored by the receiver.
6.2.4. Alternate Care-of Address 6.2.4 Binding Refresh Advice
The Binding Refresh Advice option has an alignment requirement of 2n.
Its format is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 2 | Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Refresh Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Binding Refresh Advice option is only valid in the Binding
Acknowledgement, and only on Binding Acknowledgements sent from the
mobile node's home agent in reply to a home registration. The
Refresh Interval is measured in units of four seconds, and indicates
how long before the mobile node SHOULD send a new home registration
to the home agent. The Refresh Interval MUST be set to indicate a
smaller time interval than the Lifetime value of the Binding
Acknowledgement.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
skipping to change at page 39, line 5 skipping to change at page 50, line 24
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Alternate Care-of Address option is valid only in Binding Update. The Alternate Care-of Address option is valid only in Binding Update.
The Alternate Care-of Address field contains an address to use as the 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.
6.2.5. 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
and only when present together with an Binding Authorization Data sent to a correspondent node, and only when present together with a
option. Binding Authorization Data option. When the correspondent node
authorizes the Binding Update, it needs to produce home and care-of
keygen tokens from its stored random nonce values.
The Home Nonce Index field tells the correspondent node that receives The Home Nonce Index field tells the correspondent node which nonce
the message which of its stored random nonce values is to be used to value to use when producing the home keygen token.
produce the home keygen token to authorize the Binding Update.
The Care-of Nonce Index field tells the correspondent node that The Care-of Nonce Index field is ignored in requests to delete a
receives the message which of its stored random nonce values is to binding. Otherwise, it tells the correspondent node which nonce
be used to produce the care-of keygen token to authorize the Binding value to use when producing the care-of keygen token.
Update.
6.2.6. Binding Authorization Data 6.2.7 Binding Authorization Data
The Binding Authorization Data option has an alignment requirement of The Binding Authorization Data option does not have any alignment
8n+2. Its format is as follows: requirements. 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 = 5 | Option Length | | Type = 5 | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| Authenticator | | Authenticator |
+ + + +
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authority. Rules for calculating this value depend on the used authority. Rules for calculating this value depend 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 | final dest | Mobility Header Data Mobility Data = care-of address | final dest | Mobility Header Data
Authenticator = First (96, HMAC_SHA1 (Kbm, Mobility Data)) Authenticator = First (96, HMAC_SHA1 (Kbm, Mobility Data))
Where | denotes concatenation and "final dest" is the IPv6 address Where | denotes concatenation and "final dest" is the IPv6 address of
of the final destination of the packet. "Mobility Header Data" is the final destination of the packet. "Mobility Header Data" is the
the content of the Mobility Header, excluding the Authenticator content of the Mobility Header, excluding the Authenticator field
field itself. The Authenticator value is calculated as if the itself. The Authenticator value is calculated as if the Checksum
Checksum field in the Mobility Header was zero. The Checksum in the field in the Mobility Header was zero. The Checksum in the
transmitted packet is still calculated in the usual manner, with transmitted packet is still calculated in the usual manner, with the
the calculated Authenticator being a part of the packet protected calculated Authenticator being a part of the packet protected by the
by the Checksum. Kbm is the binding management key, which is Checksum. Kbm is the binding management key, which is typically
typically created using nonces provided by the correspondent node created using nonces provided by the correspondent node (see Section
(see Section 9.4). 9.4).
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. Note that, if the message is sent to a destination which is field. Note that, if the message is sent to a destination which is
itself mobile, the "final dest" address may not be the address found itself mobile, the "final dest" address may not be the address found
in the Destination Address field of the IPv6 header; instead the in the Destination Address field of the IPv6 header; instead the
address of the true destination (e.g., its home address) should be address of the true destination (e.g., its home address) should be
used. used.
6.2.7. Binding Refresh Advice 6.3 Home Address Option
The Binding Refresh Advice option has an alignment requirement of 2n.
Its format is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 6 | Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Refresh Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Binding Refresh Advice option is only valid in the Binding
Acknowledgement, and only on Binding Acknowledgements sent from
the mobile node's home agent in reply to a home registration. The
Refresh Interval is measured in units of four seconds, and indicates
how long before the mobile node SHOULD send a new home registration
to the home agent. The Refresh Interval MUST be set to indicate
a smaller time interval than the Lifetime value of the Binding
Acknowledgement.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header | Header Ext Len | Option Type | Option Length | | Option Type | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Home Address + + Home Address +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 41, line 46 skipping to change at page 52, line 45
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.
Home Address Home Address
The home address of the mobile node sending the packet. This The home address of the mobile node sending the packet. This
address MUST be a unicast routable address. address MUST be a unicast routable address.
IPv6 requires that options appearing in a Hop-by-Hop Options IPv6 requires that options appearing in a Hop-by-Hop Options header
header or Destination Options header be aligned in a packet so that or Destination Options header be 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 an integer multiple of n octets from the start of the header, for n =
n = 1, 2, 4, or 8) [11]. The alignment requirement [11] for the Home 1, 2, 4, or 8) [11]. The alignment requirement [11] for the Home
Address option is 8n+6. Address option is 8n+6.
The three highest-order bits of the Option Type field are encoded The three highest-order bits of the Option Type field are encoded to
to indicate specific processing of the option [11]; for the Home indicate specific processing of the option [11]; for the Home Address
Address 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:
- Any IPv6 node that does not recognize the Option Type must o Any IPv6 node that does not recognize the Option Type must discard
discard the packet. the packet.
- If the packet's Destination Address was not a multicast address, o If the packet's Destination Address was not a multicast address,
return an ICMP Parameter Problem, Code 2, message to the packet's return an ICMP Parameter Problem, Code 2, message to the packet's
Source Address; otherwise, for multicast addresses, the ICMP Source Address; otherwise, for multicast addresses, the ICMP
message MUST NOT be sent. message MUST NOT be sent.
- 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:
- After the routing header, if that header is present o After the routing header, if that header is present
- Before the Fragment Header, if that header is present o Before the Fragment Header, if that header is present
- Before the AH Header or ESP Header, if either one of those o Before the AH Header or ESP Header, if either one of those headers
headers is present is 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 No state is created or modified in the receiving node as a result of
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 Mobile IPv6 defines a new routing header variant, the type 2 routing
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
"regular" IPv6 source routing, enabling firewalls to apply different "regular" IPv6 source routing, enabling firewalls to apply different
rules to source routed packets than to Mobile IPv6. This routing rules to source routed packets than to Mobile IPv6. This routing
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 All IPv6 nodes which process this routing header MUST verify that the
the address contained within is the node's own home address in address contained within is the node's own home address in order to
order to prevent packets from being forwarded outside the node. prevent packets from being forwarded outside the node. The IP
The IP address contained in the routing header, since it is the address contained in the routing header, since it is the mobile
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
skipping to change at page 44, line 20 skipping to change at page 55, line 11
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. Initialized to zero for transmission, 32-bit reserved field. Initialized to zero for transmission, and
and ignored on reception. ignored on reception.
Home Address Home Address
The Home Address of the destination Mobile Node. The Home Address of the destination Mobile Node.
For a type 2 routing header, the Hdr Ext Len MUST be 2. The Segments For a type 2 routing header, the Hdr Ext Len MUST be 2. The Segments
Left value describes the number of route segments remaining; i.e., Left value describes the number of route segments remaining; i.e.,
number of explicitly listed intermediate nodes still to be visited number of explicitly listed intermediate nodes still to be visited
before reaching the final destination. Segments Left MUST be 1. The before reaching the final destination. Segments Left MUST be 1. The
ordering rules for extension headers in an IPv6 packet are described ordering rules for extension headers in an IPv6 packet are described
in Section 4.1 of [11]. The type 2 routing header defined for Mobile in Section 4.1 of RFC 2460 [11]. The type 2 routing header defined
IPv6 follows the same ordering as other routing headers. If both a for Mobile IPv6 follows the same ordering as other routing headers.
Type 0 and a type 2 routing header are present, the type 2 routing If both a type 0 and a type 2 routing header are present, the type 2
header should follow the other routing header. routing header should follow the other routing header. A packet
containing such nested encapsulation should be created as if the
inner (type 2) routing header was constructed first and then treated
as an original packet by the outer (type 2) routing header
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 mechanism, as described in Section 11.4.1. The mobile node sends the
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 for its own home subnet prefix [16]. Home-Agents anycast address [16] for its own home subnet prefix.
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
skipping to change at page 45, line 39 skipping to change at page 56, line 30
An identifier to aid in matching Home Agent Address Discovery An identifier to aid in matching Home Agent Address Discovery
Reply messages to this Home Agent Address Discovery Request Reply messages to this Home Agent Address Discovery Request
message. 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.
The Source Address of the Home Agent Address Discovery Request The Source Address of the Home Agent Address Discovery Request
message packet MUST be one of the mobile node's current care-of message packet is typically one of the mobile node's current care-of
addresses. The home agent MUST then return the 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
registered with any home agent. Therefore, neither the nature of the
address nor the identity of the mobile node can be established at
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. Note that, at the time of performing this dynamic home mobile node.
agent address discovery procedure, it is likely that the mobile node
is not registered with any home agent within the specified anycast
group.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 46, line 51 skipping to change at page 57, line 45
The identifier from the invoking Home Agent Address Discovery The identifier from the invoking Home Agent Address Discovery
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 A list of addresses of home agents on the home link for the mobile
mobile node. The number of addresses present in the list is node. The number of addresses present in the list is indicated by
indicated by the remaining length of the IPv6 packet carrying the remaining length of the IPv6 packet carrying the Home Agent
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 The ICMP Mobile Prefix Solicitation Message is sent by a mobile node
node to its home agent while it is away from home. The purpose to its home agent while it is away from home. The purpose of the
of the message is to solicit a Mobile Prefix Advertisement from message is to solicit a Mobile Prefix Advertisement from the home
the home agent, which will allow the mobile node to gather prefix agent, which will allow the mobile node to gather prefix information
information about its home network. This information can be used to about its home network. This information can be used to configure
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 The address of the mobile node's home agent. This home agent must
must be on the link which the mobile node wishes to learn be on the link which the mobile node wishes to learn prefix
prefix information about. information about.
Hop Limit Hop Limit
Set to an initial hop limit value, similarly to any other Set to an initial hop limit value, similarly to any other unicast
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.
AH or ESP header: ESP header:
IPsec headers SHOULD be supported and used as described in IPsec headers SHOULD be supported and used as described in Section
Section 5.4. 5.4.
ICMP Fields: ICMP Fields:
Type Type
152 <To Be Assigned by IANA> 152 <To Be Assigned by IANA>
Code Code
0 0
skipping to change at page 49, line 5 skipping to change at page 59, line 29
Identifier Identifier
An identifier to aid in matching a future Mobile Prefix An identifier to aid in matching a future Mobile Prefix
Advertisement to this Mobile Prefix Solicitation. Advertisement to this Mobile Prefix Solicitation.
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.
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 A home agent will send a Mobile Prefix Advertisement to a mobile node
node to distribute prefix information about the home link while the to distribute prefix information about the home link while the mobile
mobile node is traveling away from the home network. This will occur node is traveling away from the home network. This will occur in
in response to a Mobile Prefix Solicitation with an Advertisement, response to a Mobile Prefix Solicitation with an Advertisement, or by
or by an unsolicited Advertisement sent according to the rules in an unsolicited Advertisement sent according to the rules in Section
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 | Options ... | Identifier |M|O| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IP Fields: IP Fields:
Source Address Source Address
The home agent's address as the mobile node would
expect to see it (i.e., same network prefix) The home agent's address as the mobile node would expect to see it
(i.e., same network prefix).
Destination Address Destination Address
If this message is a response to a Mobile Prefix
Solicitation, this field contains the Source Address If this message is a response to a Mobile Prefix Solicitation,
field from that packet. For unsolicited messages, this field contains the Source Address field from that packet.
the mobile node's care-of address SHOULD be used. For unsolicited messages, the mobile node's care-of address SHOULD
Note that unsolicited messages can only be sent if be used. Note that unsolicited messages can only be sent if the
the mobile node is currently registered with the mobile node is currently registered with the home agent.
home agent.
Routing header: Routing header:
A type 2 routing header MUST be included. A type 2 routing header MUST be included.
AH or ESP header: ESP header:
IPsec headers SHOULD be supported and used as described in IPsec headers SHOULD be supported and used as described in Section
Section 5.4. 5.4.
ICMP Fields: ICMP Fields:
Type Type
153 <To Be Assigned by IANA> 153 <To Be Assigned by IANA>
Code Code
0 0
Checksum Checksum
The ICMP checksum [14]. The ICMP checksum [14].
Identifier Identifier
skipping to change at page 50, line 14 skipping to change at page 60, line 43
Code Code
0 0
Checksum Checksum
The ICMP checksum [14]. The ICMP checksum [14].
Identifier Identifier
An identifier to aid in matching this Mobile Prefix An identifier to aid in matching this Mobile Prefix Advertisement
Advertisement to a previous Mobile Prefix Solicitation. to a previous Mobile Prefix Solicitation.
M
1-bit Managed Address Configuration flag. When set, hosts use the
administered (stateful) protocol for address autoconfiguration in
addition to any addresses autoconfigured using stateless address
autoconfiguration. The use of this flag is described in [12, 13].
O
1-bit Other Stateful Configuration flag. When set, hosts use the
administered (stateful) protocol for autoconfiguration of other
(non-address) information. The use of this flag is described in
[12, 13].
Reserved
This field is unused. It MUST be initialized to zero by the
sender and MUST be ignored by the receiver.
Options: Options:
Prefix Information Prefix Information
Each message contains one or more Prefix Information options. Each message contains one or more Prefix Information options.
Each option carries the prefix(es) that the mobile node should Each option carries the prefix(es) that the mobile node should use
use to configure its home address(es). Section 10.6 describes to configure its home address(es). Section 10.6 describes which
which prefixes should be advertised to the mobile node. prefixes should be advertised to the mobile node.
The Prefix Information option is defined in Section 4.6.2 The Prefix Information option is defined in Section 4.6.2 of RFC
of [12], with modifications defined in Section 7.2 of this 2461 [12], with modifications defined in Section 7.2 of this
specification. The home agent MUST use this modified Prefix specification. The home agent MUST use this modified Prefix
Information option to send the aggregate list of home network Information option to send the aggregate list of home network
prefixes as defined in Section 10.6.1. prefixes as defined in Section 10.6.1.
The Mobile Prefix Advertisement sent by the home agent MAY include
the Source Link-layer Address option defined in RFC 2461 [12], or the
Advertisement Interval option specified in Section 7.3.
Future versions of this protocol may define new option types. Mobile Future versions of this protocol may define new option types. Mobile
nodes MUST silently ignore any options they do not recognize and nodes MUST silently ignore any options they do not recognize and
continue processing the message. continue processing the message.
If the Advertisement is sent in response to a Mobile Prefix If the Advertisement is sent in response to a Mobile Prefix
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 reset if the Home Agent DHCPv6 support is
not provided. If such support is provided then they are set in
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 Mobile IPv6 modifies the format of the Router Advertisement message
message [12] by the addition of a single flag bit to indicate that [12] by the addition of a single flag bit to indicate that the router
the router sending the Advertisement message is serving as a home sending the Advertisement message is serving as a home agent on this
agent on this link. The format of the Router Advertisement message link. The format of the Router Advertisement message is as follows:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 51, line 35 skipping to change at page 62, line 34
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 indicate that the router sending this Router Advertisement is also
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 (Sections 10.5 and 11.4.1). discovery mechanism.
However, Neighbor Discovery [12] only advertises a router's However, Neighbor Discovery [12] only advertises a router's
link-local address, by requiring this address to be used as the IP link-local address, by requiring this address to be used as the IP
Source Address of each Router Advertisement. Source 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:
skipping to change at page 52, line 45 skipping to change at page 63, line 35
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 1-bit router address flag. When set, indicates that the Prefix
Prefix field, in addition to advertising the indicated prefix, field, in addition to advertising the indicated prefix, contains a
contains a complete IP address assigned to the sending router. complete IP address assigned to the sending router. This router
This router IP address has the same scope and conforms to the IP address has the same scope and conforms to the same lifetime
same lifetime values as the advertised prefix. This use of values as the advertised prefix. This use of the Prefix field is
the Prefix field is compatible with its use in advertising compatible with its use in advertising the prefix itself, since
the prefix itself, since Prefix Advertisement uses only the Prefix Advertisement uses only the leading number Prefix bits
leading number Prefix bits specified by the Prefix Length specified by the Prefix Length field. Interpretation of this flag
field. Interpretation of this flag bit is thus independent bit is thus independent of the processing required for the On-Link
of the processing required for the On-Link (L) and Autonomous (L) and Autonomous Address-Configuration (A) flag bits.
Address-Configuration (A) flag bits.
Reserved1 Reserved1
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.
In a Router Advertisement, a home agent MUST, and all other routers In a Router Advertisement, a home agent MUST, and all other routers
MAY, include at least one Prefix Information option with the Router MAY, include at least one Prefix Information option with the Router
Address (R) bit set. Neighbor Discovery specifies that, if including Address (R) bit set. Neighbor Discovery specifies that, if including
all options in a Router Advertisement causes the size of the all options in a Router Advertisement causes the size of the
Advertisement to exceed the link MTU, multiple Advertisements can be Advertisement to exceed the link MTU, multiple Advertisements can be
sent, each containing a subset of the options [12]. In this case, at sent, each containing a subset of the options [12]. In this case, at
least one (not all) of these multiple Advertisements being sent needs least one (not all) of these multiple Advertisements being sent needs
to satisfy the above requirement. to satisfy the above requirement.
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 8-bit unsigned integer. The length of the option (including the
the type and length fields) in units of 8 octets. The value of type and length fields) in units of 8 octets. The value of this
this field MUST be 1. 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 Router Advertisement
messages sent by this router on this network interface. Using messages sent by this router on this network interface. Using the
the conceptual router configuration variables defined by conceptual router configuration variables defined by Neighbor
Neighbor Discovery [12], this field MUST be equal to the value Discovery [12], this field MUST be equal to the value
MaxRtrAdvInterval, expressed in milliseconds. MaxRtrAdvInterval, expressed 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 8-bit unsigned integer. The length of the option (including the
the type and length fields) in units of 8 octets. The value of type and length fields) in units of 8 octets. The value of this
this field MUST be 1. 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.
Home Agent Preference Home Agent Preference
16-bit signed, two's complement integer. The preference for 16-bit unsigned integer. The preference for the home agent
the home agent sending this Router Advertisement, for use in sending this Router Advertisement, for use in ordering the
ordering the addresses returned to a mobile node in the Home addresses returned to a mobile node in the Home Agent Addresses
Agent Addresses field of a Home Agent Address Discovery Reply field of a Home Agent Address Discovery Reply message. Higher
message. Higher values mean more preferable. If this option values mean more preferable. If this option is not included in a
is not included in a Router Advertisement in which the Home Router Advertisement in which the Home Agent (H) bit is set, the
Agent (H) bit is set, the preference value for this home agent preference value for this home agent MUST be considered to be 0.
SHOULD be considered to be 0. Values greater than 0 indicate a Greater values indicate a more preferable home agent than lower
home agent more preferable than this default value, and values values.
less than 0 indicate a less preferable home agent.
The manual configuration of the Home Agent Preference value The manual configuration of the Home Agent Preference value is
is described in Section 8.4. In addition, the sending home described in Section 8.4. In addition, the sending home agent MAY
agent MAY dynamically set the Home Agent Preference value, for dynamically set the Home Agent Preference value, for example
example basing it on the number of mobile nodes it is currently basing it on the number of mobile nodes it is currently serving or
serving or on its remaining resources for serving additional on its remaining resources for serving additional mobile nodes;
mobile nodes; such dynamic settings are beyond the scope of such dynamic settings are beyond the scope of this document. Any
this document. Any such dynamic setting of the Home Agent such dynamic setting of the Home Agent Preference, however, MUST
Preference, however, MUST set the preference appropriately, set the preference appropriately, relative to the default Home
relative to the default Home Agent Preference value of 0 that Agent Preference value of 0 that may be in use by some home agents
may be in use by some home agents on this link (i.e., a home on this link (i.e., a home agent not including a Home Agent
agent not including a Home Agent Information option in its Information option in its Router Advertisements will be considered
Router Advertisements will be considered to have a Home Agent to have a Home Agent Preference value of 0).
Preference value of 0).
Home Agent Lifetime Home Agent Lifetime
16-bit unsigned integer. The lifetime associated with the 16-bit unsigned integer. The lifetime associated with the home
home agent in units of seconds. The default value is the same agent in units of seconds. The default value is the same as the
as the Router Lifetime, as specified in the main body of the Router Lifetime, as specified in the main body of the Router
Router Advertisement. The maximum value corresponds to 18.2 Advertisement. The maximum value corresponds to 18.2 hours. A
hours. A value of 0 MUST NOT be used. The Home Agent Lifetime value of 0 MUST NOT be used. The Home Agent Lifetime applies only
applies only to this router's usefulness as a home agent; it to this router's usefulness as a home agent; it does not apply to
does not apply to information contained in other message fields information contained in other message fields or options.
or options.
Home agents MAY include this option in their Router Advertisements. Home agents MAY include this option in their Router Advertisements.
This option MUST NOT be included in a Router Advertisement in which This option MUST NOT be included in a Router Advertisement in which
the Home Agent (H) bit (see Section 7.1) is not set. If this option the Home Agent (H) bit (see Section 7.1) is not set. If this option
is not included in a Router Advertisement in which the Home Agent (H) is not included in a Router Advertisement in which the Home Agent (H)
bit is set, the lifetime for this home agent MUST be considered to bit is set, the lifetime for this home agent MUST be considered to be
be the same as the Router Lifetime in the Router Advertisement. the same as the Router Lifetime in the Router Advertisement. If
If multiple Advertisements are being sent instead of a single multiple Advertisements are being sent instead of a single larger
larger unsolicited multicast Advertisement, all of the multiple unsolicited multicast Advertisement, all of the multiple
Advertisements with the Router Address (R) bit set MUST include this Advertisements with the Router Address (R) bit set MUST include this
option with the same contents, otherwise this option MUST be omitted option with the same contents, otherwise this option MUST be omitted
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 If both the Home Agent Preference and Home Agent Lifetime are set to
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 Modified Neighbor Solicitation Message Format
Mobile nodes may need to send Neighbor Solicitations to their home
agent when the home agent still has a binding for them. As the home
agent defends the mobile node's addresses on the home link, the
mobile node can not use its own addresses until it it successfully
deletes the binding. However, in order to do this it must send a
Binding Update to the home agent, and possibly find its link-layer
address.
The modified Neighbor Solicitation message allows this to be done
with the IP Source Address set to the unspecified address and the
ICMP Code field set to 1. The modified format MUST NOT be used
except for the purpose of discovering the link-layer address of a
home agent when the mobile node is returning home (Section 11.5.4).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Target Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ...
+-+-+-+-+-+-+-+-+-+-+-+-
This format represents the following changes over that originally
specified for Neighbor Discovery [12]:
IP Fields:
Source Address
The unspecified address.
ICMP Fields:
Code
1
Upon receiving a Neighbor Solicitation message from the unspecified
address with the Code field set to 1, home agents MUST process this
message as described in Section 7.2.3 of RFC 2461 [12]. Such
messages MUST NOT be considered as a sign that the sending node is
performing Duplicate Address Detection [13].
7.6 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 "Routers generate Router Advertisements frequently enough that
that hosts will learn of their presence within a few hosts will learn of their presence within a few minutes, but not
minutes, but not frequently enough to rely on an absence frequently enough to rely on an absence of advertisements to
of advertisements to detect router failure; a separate detect router failure; a separate Neighbor Unreachability
Neighbor Unreachability Detection algorithm provides failure Detection algorithm provides failure detection."
detection."
This limitation, however, is not suitable to providing timely This limitation, however, is not suitable to providing timely
movement detection for mobile nodes. Mobile nodes detect their movement detection for mobile nodes. Mobile nodes detect their own
own movement by learning the presence of new routers as the mobile movement by learning the presence of new routers as the mobile node
node moves into wireless transmission range of them (or physically moves into wireless transmission range of them (or physically
connects to a new wired network), and by learning that previous connects to a new wired network), and by learning that previous
routers are no longer reachable. Mobile nodes MUST be able to routers are no longer reachable. Mobile nodes MUST be able to
quickly detect when they move to a link served by a new router, so quickly detect when they move to a link served by a new router, so
that they can acquire a new care-of address and send Binding Updates that they can acquire a new care-of address and send Binding Updates
to register this care-of address with their home agent and to notify to register this care-of address with their home agent and to notify
correspondent nodes as needed. correspondent nodes as needed.
Mobile IPv6 relaxes this limit such that routers MAY send unsolicited One method which can provide for faster movement detection, is to
multicast Router Advertisements more frequently. This is important increase the rate at which unsolicited Router Advertisements are
on network interfaces where the router is expecting to provide sent. Mobile IPv6 relaxes this limit such that routers MAY send
unsolicited multicast Router Advertisements more frequently. This
method can be applied where the router is expecting to provide
service to visiting mobile nodes (e.g., wireless network interfaces), service to visiting mobile nodes (e.g., wireless network interfaces),
or on which it is serving as a home agent to one or more mobile or on which it is serving as a home agent to one or more mobile nodes
nodes (who may return home and need to hear its Advertisements). (who may return home and need to hear its Advertisements).
Such routers SHOULD be configured with a smaller MinRtrAdvInterval
value and MaxRtrAdvInterval value, to allow sending of unsolicited
multicast Router Advertisements more often. Recommended values for
these limits are:
- MinRtrAdvInterval 0.05 seconds Routers supporting mobility SHOULD be able to be configured with a
smaller MinRtrAdvInterval value and MaxRtrAdvInterval value to allow
sending of unsolicited multicast Router Advertisements more often.
The minimum allowed values are:
- MaxRtrAdvInterval 1.5 seconds o MinRtrAdvInterval 0.03 seconds
Use of these modified limits MUST be configurable, and specific o MaxRtrAdvInterval 0.07 seconds
knowledge of the type of network interface in use SHOULD be taken
into account in configuring these limits for each network interface. In the case where the minimum intervals and delays are used, the mean
Note that multicast Router Advertisements are not always required time between unsolicited multicast router advertisements is 50ms.
in certain wireless networks that have limited bandwidth. Mobility Use of these modified limits MUST be configurable (see also the
configuration variable MinDelayBetweenRas in Section 13 which may
also have to be modified accordingly). Systems where these values
are available MUST NOT default to them, and SHOULD default to values
specified in RFC 2461. Knowledge of the type of network interface
and operating environment SHOULD be taken into account in configuring
these limits for each network interface. This is important with some
wireless links, where increasing the frequency of multicast beacons
can cause considerable overhead. Routers SHOULD adhere to the
intervals specified in RFC 2461 [12], if this overhead is likely to
cause service degradation.
Additionally, the possible low values of MaxRtrAdvInterval may cause
some problems with movement detection in some mobile nodes. To
ensure that this is not a problem, Routers SHOULD add 20ms to any
Advertisement Intervals sent in RAs, which are below 200 ms, in order
to account for scheduling granularities on both the MN and the
Router.
Note that multicast Router Advertisements are not always required in
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.
The MaxRtrAdvInterval in such a case can be set to some high value. The MinRtrAdvInterval and MaxRtrAdvInterval in such a case can be set
to some high values.
When sending unsolicited multicast Router Advertisements more When sending unsolicited multicast Router Advertisements more
frequently than the standard limit on unsolicited multicast frequently than the limit specified in RFC 2461 [12], the sending
Advertisement frequency, the sending router need not include all router need not include all options in each of these Advertisements,
options in each of these Advertisements, but it SHOULD include at but it SHOULD include at least one Prefix Information option with the
least one Prefix Information option with the Router Address (R) bit Router Address (R) bit set (Section 7.2) in each.
set (Section 7.2) in each.
7.6. Changes to Sending Router Solicitations
In addition to the limit on routers sending unsolicited multicast
Router Advertisement messages (Section 7.5), Neighbor Discovery
defines limits on nodes sending Router Solicitation messages, such
that a node SHOULD send no more than 3 Router Solicitations, and that
these 3 transmissions SHOULD be spaced at least 4 seconds apart.
However, these limits prevent a mobile node from finding a new
default router (and thus a new care-of address) quickly as it moves
about.
Mobile IPv6 relaxes this limit such that, while a mobile node is away
from home, it MAY send Router Solicitations more frequently. The
following limits for sending Router Solicitations are recommended for
mobile nodes while away from home:
- A mobile node that is not configured with any current care-of
address (e.g., the mobile node has moved since its previous
care-of address was configured), MAY send more than the defined
Neighbor Discovery limit of MAX_RTR_SOLICITATIONS Router
Solicitations.
- The rate at which a mobile node sends Router Solicitations MUST
be limited, although a mobile node MAY send Router Solicitations
more frequently than the defined Neighbor Discovery limit of
RTR_SOLICITATION_INTERVAL seconds. The minimum interval MUST
be configurable, and specific knowledge of the type of network
interface in use SHOULD be taken into account in configuring this
limit for each network interface. A recommended minimum interval
is 1 second.
- After sending at most MAX_RTR_SOLICITATIONS Router Solicitations,
a mobile node MUST reduce the rate at which it sends subsequent
Router Solicitations. Subsequent Router Solicitations SHOULD
be sent using a binary exponential back-off mechanism, doubling
the interval between consecutive Router Solicitations, up to a
maximum interval. The maximum interval MUST be configurable and
SHOULD be chosen appropriately based on the characteristics of
the type of network interface in use.
- While still searching for a new default router and care-of
address, a mobile node MUST NOT increase the rate at which it
sends Router Solicitations unless it has received a positive
indication (such as from lower network layers) that it has moved
to a new link. After successfully acquiring a new care-of
address, the mobile node SHOULD also increase the rate at which
it will send Router Solicitations when it next begins searching
for a new default router and care-of address.
- A mobile node that is currently configured with a care-of address Home agents MUST include the Source Link-Layer Address option in all
SHOULD NOT send Router Solicitations to the default router Router Advertisements they send.
on its current link, until its movement detection algorithm
(Section 11.5.1) determines that it has moved and that its
current care-of address might no longer be valid.
7.7. Changes to Duplicate Address Detection 7.7 Changes to Duplicate Address Detection
Upon failing Duplicate Address Detection, [13] requires IPv6 nodes to Upon failing Duplicate Address Detection, [13] requires IPv6 nodes to
stop using the address and wait for reconfiguration. In addition, if stop using the address and wait for reconfiguration. In addition, if
the failed address was a link-local address formed from an interface the failed address was a link-local address formed from an interface
identifier, the interface should be disabled. identifier, the interface should be disabled.
Mobile IPv6 extends this behavior as follows. Upon failing Duplicate Mobile nodes that wish to avoid this situation MAY use temporary
Address Detection while away from home, the mobile node SHOULD stop link-local addresses as follows. The mobile node SHOULD generate a
using the address on this interface until the mobile node moves to random interface identifier and use it for assigning itself a
another link. The mobile node SHOULD NOT wait for reconfiguration or link-local address. In order to do this, the mobile node applies to
disable the interface. the link-local address the procedure described in RFC 3041 [18] for
global addresses. At most 5 consecutive attempts SHOULD be performed
The mobile node MUST NOT discard the home address based on a failure to generate such addresses and test them through Duplicate Address
of a link-local address with the same interface identifier. Instead, Detection. If after these attempts no unique address was found, the
the mobile node SHOULD generate a new random interface identifier and mobile node SHOULD log a system error and give up attempting to find
use it for assigning itself a new link-local address. In order to do a link-local address on that interface, until the node moves to a new
this, the mobile node applies to the link-local address the procedure link.
described in [17] for global addresses. At most 5 consecutive
attempts SHOULD be performed to generate such addresses and test
them through Duplicate Address Detection. If after these attempts
no unique address was found, the mobile node SHOULD log a system
error and give up attempting to find a link-local address on that
interface, until the node moves to a new link.
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:
- All IPv6 nodes. o All IPv6 nodes.
- All IPv6 nodes with support for route optimization. o All IPv6 nodes with support for route optimization.
- All IPv6 routers. o All IPv6 routers.
- All Mobile IPv6 home agents. o All Mobile IPv6 home agents.
- All Mobile IPv6 mobile nodes. o All Mobile IPv6 mobile nodes.
It is outside the scope of this specification to specify which It is outside the scope of this specification to specify which of
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 requirements from a mobile node. There are no Mobile IPv6 specific MUST
for such nodes, and standard IPv6 techniques are sufficient. requirements for such nodes, and basic IPv6 techniques are
sufficient. If a mobile node attempts to set up route optimization
with a node with only basic IPv6 support, an ICMP error will signal
that the node does not support such optimizations, and communications
will flow through the home agent.
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, beneficial for robustness and operation of the IPv6 Internet, for the following reasons:
reduction of jitter and latency, and necessary to avoid congestion
in the home network. The following requirements apply to all
correspondent nodes that support route optimization:
- The node MUST be able validate a Home Address option using an o Avoidance of congestion in the home network, and enabling the use
of lower-performance home agent equipment even for supporting
thousands of mobile nodes.
o Reduced network load across the entire Internet, as mobile devices
begin to predominate. At the time this is being written, laptop
computers already outsell desktops and wireless telephones far
outsell laptops.
o Reduction of jitter and latency for the communications.
o Greater likelihood of success for QoS signaling as tunneling is
avoided and, again, fewer sources of congestion.
o Improved robustness against network partitions, congestion, and
other problems, since fewer routing path segments are traversed.
These effects combine to enable much better performance and
robustness for communications between mobile nodes and IPv6
correspondent nodes.
The following requirements apply to all correspondent nodes that
support route optimization:
o The node MUST be able 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.
- The node MUST be able to insert a type 2 routing header o The node MUST be able to insert a type 2 routing header into
into packets to be sent to a mobile node, as described in packets to be sent to a mobile node, as described in Section
Section 9.3.2. 9.3.2.
- 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 drop all packets that it MUST ignore type 2 routing headers and drop all packets that it
has received with such headers. has received with such headers.
- The node SHOULD be able to interpret ICMP messages as described o The node SHOULD be able to interpret ICMP messages as described in
in Section 9.3.4. Section 9.3.4.
- The node MUST be able to send Binding Error messages as described o The node MUST be able to send Binding Error messages as described
in Section 9.3.3. in Section 9.3.3.
- The node MUST be able to process Mobility Headers as described in o The node MUST be able to process Mobility Headers as described in
Section 9.2. Section 9.2.
- The node MUST be able to participate in a return routability o The node MUST be able to participate in a return routability
procedure (Section 9.4). procedure (Section 9.4).
- The node MUST be able to process Binding Update messages o The node MUST be able to process Binding Update messages (Section
(Section 9.5). 9.5).
- The node MUST be able to return a Binding Acknowledgement o The node MUST be able to return a Binding Acknowledgement (Section
(Section 9.5.4). 9.5.4).
- The node MUST be able to maintain a Binding Cache of the o The node MUST be able to maintain a Binding Cache of the bindings
bindings received in accepted Binding Updates, as described in received in accepted Binding Updates, as described in Section 9.1
Sections 9.1 and 9.6. and Section 9.6.
8.3. All IPv6 Routers o The node MUST allow route optimization to be administratively
enabled or disabled. The default SHOULD be enabled.
All IPv6 routers, even those not serving as a home agent for 8.3 All IPv6 Routers
Mobile IPv6, have an effect on how well mobile nodes can communicate:
- Every IPv6 router SHOULD be able to send an Advertisement All IPv6 routers, even those not serving as a home agent for Mobile
Interval option (Section 7.3) in each of its Router IPv6, have an effect on how well mobile nodes can communicate:
Advertisements [12], to aid movement detection by mobile nodes
(as in Section 11.5.1). The use of this option in Router
Advertisements MUST be configurable.
- Every IPv6 router SHOULD be able to support sending unsolicited o Every IPv6 router SHOULD be able to send an Advertisement Interval
option (Section 7.3) in each of its Router Advertisements [12], to
aid movement detection by mobile nodes (as in Section 11.5.1).
The use of this option in Router Advertisements MUST be
configurable.
o Every IPv6 router SHOULD be able to support sending unsolicited
multicast Router Advertisements at the faster rate described in multicast Router Advertisements at the faster rate described in
Section 7.5. The use of this faster rate MUST be configurable. Section 7.6. The use of this faster rate MUST be configurable.
- 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).
- Filtering routers SHOULD support different rules for type 0 o Filtering routers SHOULD support different rules for type 0 and
and type 2 routing headers (see Section 6.4) so that filtering type 2 routing headers (see Section 6.4) so that filtering of
of source routed packets (type 0) will not necessarily limit source routed packets (type 0) will not necessarily limit Mobile
Mobile IPv6 traffic which is delivered via type 2 routing IPv6 traffic which is delivered via type 2 routing headers.
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:
- 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 (Sections 10.1 and 10.3.1). agent (Section 10.1 and Section 10.3.1).
- Every home agent MUST be able to intercept packets (using o Every home agent MUST be able to intercept packets (using proxy
proxy Neighbor Discovery [12]) addressed to a mobile node for Neighbor Discovery [12]) addressed to a mobile node for which it
which it is currently serving as the home agent, on that mobile is currently serving as the home agent, on that mobile node's home
node's home link, while the mobile node is away from home link, while the mobile node is away from home (Section 10.4.1).
(Section 10.4.1).
- Every home agent MUST be able to encapsulate [15] such o Every home agent MUST be able to encapsulate [15] such intercepted
intercepted packets in order to tunnel them to the primary packets in order to tunnel them to the primary care-of address for
care-of address for the mobile node indicated in its binding in the mobile node indicated in its binding in the home agent's
the home agent's Binding Cache (Section 10.4.2). Binding Cache (Section 10.4.2).
- Every home agent MUST support decapsulating [15] reverse tunneled o Every home agent MUST support decapsulating [15] reverse tunneled
packets sent to it from a mobile node's home address. Every home packets sent to it from a mobile node's home address. Every home
agent MUST also check that the source address in the tunneled agent MUST also check that the source address in the tunneled
packets corresponds to the currently registered location of the packets corresponds to the currently registered location of the
mobile node (Section 10.4.3). mobile node (Section 10.4.5).
- The node MUST be able to process Mobility Headers as described in o The node MUST be able to process Mobility Headers as described in
Section 10.2. Section 10.2.
- Every home agent MUST be able to return a Binding Acknowledgement o Every home agent MUST be able to return a Binding Acknowledgement
in response to a Binding Update (Section 10.3.1). in response to a Binding Update (Section 10.3.1).
- Every home agent MUST maintain a separate Home Agents List for o Every home agent MUST maintain a separate Home Agents List for
each link on which it is serving as a home agent, as described in each link on which it is serving as a home agent, as described in
Sections 10.1 and 10.5.1. Section 10.1 and Section 10.5.1.
- Every home agent MUST be able to accept packets addressed to o Every home agent MUST be able to accept packets addressed to the
the Mobile IPv6 Home-Agents anycast address for the subnet Mobile IPv6 Home-Agents anycast address [16] for the subnet on
on which it is serving as a home agent [16], and MUST be which it is serving as a home agent, and MUST be able to
able to participate in dynamic home agent address discovery participate in dynamic home agent address discovery (Section
(Section 10.5). 10.5).
- Every home agent SHOULD support a configuration mechanism to o Every home agent SHOULD support a configuration mechanism to allow
allow a system administrator to manually set the value to be sent a system administrator to manually set the value to be sent by
by this home agent in the Home Agent Preference field of the Home this home agent in the Home Agent Preference field of the Home
Agent Information Option in Router Advertisements that it sends Agent Information Option in Router Advertisements that it sends
(Section 7.4). (Section 7.4).
- Every home agent SHOULD support sending ICMP Mobile Prefix o Every home agent SHOULD support sending ICMP Mobile Prefix
Advertisements (Section 6.8), and SHOULD respond to Mobile Prefix Advertisements (Section 6.8), and SHOULD respond to Mobile Prefix
Solicitations (Section 6.7). This behavior MUST be configurable, Solicitations (Section 6.7). This behavior MUST be configurable,
so that home agents can be configured to avoid sending such so that home agents can be configured to avoid sending such Prefix
Prefix Advertisements according to the needs of the network Advertisements according to the needs of the network
administration in the home domain. administration in the home domain.
- Every home agent MUST support IPsec ESP for protection of packets o Every home agent MUST support IPsec ESP for protection of packets
belonging to the return routability procedure (Section 10.4.4). belonging to the return routability procedure (Section 10.4.6).
8.5. IPv6 Mobile Nodes o Every home agent SHOULD support the multicast group membership
control protocols as described in Section 10.4.3. If this support
is provided, the home agent MUST be capable of using it to
determine which multicast data packets to forward via the tunnel
to the mobile node.
o Home agents MAY support stateful address autoconfiguration for
mobile nodes as described in Section 10.4.4.
o Every home agent MUST support the extended Neighbor Solicitation
message format described in Section 7.5.
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:
- The node MUST maintain a Binding Update List (Section 11.1). o The node MUST maintain a Binding Update List (Section 11.1).
- The node MUST support sending packets containing a Home o The node MUST support sending packets containing a Home Address
Address option (Section 11.3.1), and follow the required IPsec option (Section 11.3.1), and follow the required IPsec interaction
interaction (Section 11.3.2). (Section 11.3.2).
- The node MUST be able to perform IPv6 encapsulation and o The node MUST be able to perform IPv6 encapsulation and
decapsulation [15]. decapsulation [15].
- The node MUST be able to process type 2 routing header as defined o The node MUST be able to process type 2 routing header as defined
in Sections 6.4 and 11.3.3. in Section 6.4 and Section 11.3.3.
- The node MUST support receiving a Binding Error message o The node MUST support receiving a Binding Error message (Section
(Section 11.7.5). 11.3.6).
- The node SHOULD support receiving ICMP errors (Section 11.3.4). o The node SHOULD support receiving ICMP errors (Section 11.3.5).
- The node MUST support movement detection, care-of address o The node MUST support movement detection, care-of address
formation, and returning home (Section 11.5). formation, and returning home (Section 11.5).
- The node MUST be able to process Mobility Headers as described in o The node MUST be able to process Mobility Headers as described in
Section 11.2. Section 11.2.
- The node MUST support the return routability procedure o The node MUST support the return routability procedure (Section
(Section 11.6). 11.6).
- The node MUST be able to send Binding Updates, as specified in o The node MUST be able to send Binding Updates, as specified in
Sections 11.7.1 and 11.7.2. Section 11.7.1 and Section 11.7.2.
- The node MUST be able to receive and process Binding o The node MUST be able to receive and process Binding
Acknowledgements, as specified in Section 11.7.3. Acknowledgements, as specified in Section 11.7.3.
- The node MUST support receiving a Binding Refresh Request o The node MUST support receiving a Binding Refresh Request (Section
(Section 6.1.2), by responding with a Binding Update. 6.1.2), by responding with a Binding Update.
- The node MUST support receiving Mobile Prefix Advertisements o The node MUST support receiving Mobile Prefix Advertisements
(Section 11.4.3) and reconfiguring its home address based on the (Section 11.4.3) and reconfiguring its home address based on the
prefix information contained therein. prefix information contained therein.
- The node SHOULD support use of the dynamic home agent address o The node SHOULD support use of the dynamic home agent address
discovery mechanism, as described in Section 11.4.1. discovery mechanism, as described in Section 11.4.1.
o The node MUST allow route optimization to be administratively
enabled or disabled. The default SHOULD be enabled.
o The node MAY support the multicast address listener part of a
multicast group membership protocol as described in Section
11.3.4. If this support is provided, the mobile node MUST be able
to receive tunneled multicast packets from the home agent.
o The node MAY support stateful address autoconfiguration mechanisms
such as DHCPv6 [29] on the interface represented by the tunnel to
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 IPv6 addresses. The maintained by each IPv6 node for each of its IPv6 addresses. The
Binding Cache MAY be implemented in any manner consistent with the Binding Cache MAY be implemented in any manner consistent with the
external behavior described in this document, for example by being external behavior described in this document, for example by being
combined with the node's Destination Cache as maintained by Neighbor combined with the node's Destination Cache as maintained by Neighbor
Discovery [12]. When sending a packet, the Binding Cache is searched Discovery [12]. When sending a packet, the Binding Cache is searched
before the Neighbor Discovery conceptual Destination Cache [12]. before the Neighbor Discovery conceptual Destination Cache [12].
That is, any Binding Cache entry for this destination SHOULD take That is, any Binding Cache entry for this destination SHOULD take
precedence over any Destination Cache entry for the same destination. precedence over any Destination Cache entry for the same destination.
Each Binding Cache entry conceptually contains the following fields: Each Binding Cache entry conceptually contains the following fields:
- The home address of the mobile node for which this is the Binding o The home address of the mobile node for which this is the Binding
Cache entry. This field is used as the key for searching the Cache entry. This field is used as the key for searching the
Binding Cache for the destination address of a packet being sent. Binding Cache for the destination address of a packet being sent.
If the destination address of the packet matches the home address If the destination address of the packet matches the home address
in the Binding Cache entry, this entry SHOULD be used in routing in the Binding Cache entry, this entry SHOULD be used in routing
that packet. that packet.
- The care-of address for the mobile node indicated by the home o The care-of address for the mobile node indicated by the home
address field in this Binding Cache entry. If the destination address field in this Binding Cache entry. If the destination
address of a packet being routed by a node matches the home address of a packet being routed by a node matches the home
address in this entry, the packet SHOULD be routed to this address in this entry, the packet SHOULD be routed to this care-of
care-of address. This is described in Section 9.3.2 for packets address. This is described in Section 9.3.2 for packets
originated by this node. originated by this node.
- A lifetime value, indicating the remaining lifetime for this o A lifetime value, indicating the remaining lifetime for this
Binding Cache entry. The lifetime value is initialized from Binding Cache entry. The lifetime value is initialized from the
the Lifetime field in the Binding Update that created or last Lifetime field in the Binding Update that created or last modified
modified this Binding Cache entry. Once the lifetime of this this Binding Cache entry. Once the lifetime of this entry
entry expires, the entry MUST be deleted from the Binding Cache. expires, the entry MUST be deleted from the Binding Cache.
- A flag indicating whether or not this Binding Cache entry is a o A flag indicating whether or not this Binding Cache entry is a
home registration entry. home registration entry.
- The maximum value of the Sequence Number field received in o The maximum value of the Sequence Number field received in
previous Binding Updates for this mobile node home address. The previous Binding Updates for this mobile node home address. The
Sequence Number field is 16 bits long. Sequence Number values Sequence Number field is 16 bits long. Sequence Number values
MUST be compared modulo 2**16 as explained in Section 9.5.1. MUST be compared modulo 2**16 as explained in Section 9.5.1.
- Usage information for this Binding Cache entry. This is needed o Usage information for this Binding Cache entry. This is needed to
to implement the cache replacement policy in use in the Binding implement the cache replacement policy in use in the Binding
Cache. Recent use of a cache entry also serves as an indication Cache. Recent use of a cache entry also serves as an indication
that a Binding Refresh Request should be sent when the lifetime that a Binding Refresh Request should be sent when the lifetime of
of 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 one of a node's IPv6 addresses may contain at most one entry for each
each mobile node home address. The contents of a node's Binding mobile node home address. The contents of a node's Binding Cache
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:
1. 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 SHOULD issue a Otherwise, the node MUST discard the message and issue a Binding
Binding Error message as described in Section 9.3.3, with Status Error message as described in Section 9.3.3, with Status field set
field set to 2 (unrecognized MH Type value). to 2 (unrecognized MH Type value).
2. The Payload Proto field MUST be IPPROTO_NONE (59 decimal). o The Payload Proto field MUST be IPPROTO_NONE (59 decimal).
Otherwise, the node MUST silently discard the message. Otherwise, the node MUST discard the message and SHOULD send ICMP
Parameter Problem [14], Code 0, to the Source Address of the
packet.
3. 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.
Subsequent checks depend on the particular Mobility Header, as o The Header Len field in the Mobility Header MUST NOT be less than
specified in Sections 9.4 and 9.5. the length specified for this particular type of message in
Section 6.1. Otherwise, the node MUST discard the message and
SHOULD send ICMP Parameter Problem [14], Code 0, to the Source
Address of the packet.
9.3. Packet Processing Subsequent checks depend on the particular Mobility Header.
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 Destination Option 9.3.1 Receiving Packets with Home Address Option
If the correspondent node has a Binding Cache entry for the home
address of a mobile node, packets sent by the mobile node MAY include
a Home Address destination 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.
Packets containing a Home Address option MUST also be dropped if Mobile nodes are expected to include a Home Address destination
there is no corresponding Binding Cache entry for the given home option in a packet they believe the correspondent node has a Binding
address. A corresponding Binding Cache entry MUST have the currently Cache entry for the home address of a mobile node. Packets
registered care-of address equal to the source address of the packet. containing a Home Address option MUST be dropped if there is no
These tests MUST NOT be done for packets that contain a Binding corresponding Binding Cache entry. A corresponding Binding Cache
Update and a Home Address option. entry MUST have the same home address as appears in the Home Address
destination option, and the currently registered care-of address MUST
be equal to the source address of the packet. These tests MUST NOT
be done for packets that contain a Home Address option and a Binding
Update, or for IPsec AH or ESP packets.
If the packet is dropped due the above tests, the correspondent node If the packet is dropped due the above tests, the correspondent node
SHOULD send the Binding Error message as described in Section 9.3.3. SHOULD send the Binding Error message as described in Section 9.3.3.
The Status field in this message should be set to 1 (unknown binding The Status field in this message should be set to 1 (unknown binding
for Home Address destination option). for Home Address destination option).
The correspondent node MUST process the option in a manner consistent The correspondent node MUST process the option in a manner consistent
with exchanging the Home Address field from the Home Address option with exchanging the Home Address field from the Home Address option
into the IPv6 header and replacing the original value of the Source into the IPv6 header and replacing the original value of the Source
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 to process the packet without the knowledge that it MUST be possible for upper layers to process the packet without the
came originally from a care-of address or that a Home Address option knowledge that it came originally from a care-of address or that a
was used. Home Address option was used.
No additional authentication of the Home Address option is No additional authentication of the Home Address option is required,
required, except that if the IPv6 header of a packet is covered except that if the IPv6 header of a packet is covered by
by authentication, then that authentication MUST also cover the authentication, then that authentication MUST also cover the Home
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 authentication computation. By requiring that any authentication the authentication computation. By requiring that any authentication
of the IPv6 header also cover the Home Address option, the security of the IPv6 header also cover the Home Address option, the security
of the Source Address field in the IPv6 header is not compromised by of the Source Address field in the IPv6 header is not compromised by
the presence of a Home Address option. When attempting to verify the presence of a Home Address option.
authentication data in a packet that contains a Home Address option,
the receiving node MUST make the calculation as if the care-of
address were present in the Home Address option, and the home address
were present in the source IPv6 address field of the IPv6 header.
This conforms with the calculation specified in Section 11.3.2.
9.3.2. Sending Packets to a Mobile Node When attempting to verify authentication data in a packet that
contains a Home Address option, the receiving node MUST calculate the
authentication data as if the following were true: The Home Address
option contains the care-of address, and the source IPv6 address
field of the IPv6 header contains the home address. This conforms
with the calculation specified in Section 11.3.2.
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. Assuming there are no additional routing of its care-of address. When calculating authentication data in a
headers in this packet beyond those needed by Mobile IPv6, the mobile packet that contains a type 2 routing header, the correspondent node
node sets the fields in the packet's IPv6 header and routing header MUST calculate the authentication data as if the following were true:
as follows: The routing header contains the care-of address, the destination IPv6
address field of the IPv6 header contains the home address, and the
Segments Left field is zero. The IPsec Security Policy Database look
MUST based on the mobile node's home address.
- The Destination Address in the packet's IPv6 header is set to the For instance, assuming there are no additional routing headers in
this packet beyond those needed by Mobile IPv6, the correspondent
node could set the fields in the packet's IPv6 header and routing
header as follows:
o The Destination Address in the packet's IPv6 header is set to the
mobile node's home address (the original destination address to mobile node's home address (the original destination address to
which the packet was being sent). which the packet was being sent).
- The routing header is initialized to contain a single route o The routing header is initialized to contain a single route
segment, containing the mobile node's care-of address copied from segment, containing the mobile node's care-of address copied from
the Binding Cache entry. The Segments Left field is, however, the Binding Cache entry. The Segments Left field is, however,
temporarily set to zero. temporarily set to zero.
The IP layer will insert the routing header before performing IPsec The IP layer will insert the routing header before performing any
processing. The IPsec Security Policy Database will be consulted necessary IPsec processing. Once all IPsec processing has been
based on the IP source address and the destination address (which performed, the node swaps the IPv6 destination field with the Home
will be the mobile node's home address). Once all IPsec processing Address field in the routing header, sets the Segments Left field to
has been performed, the node swaps the IPv6 destination field with one, and sends the packet. This ensures the AH calculation is done
the Home Address field in the routing header, sets the Segments Left on the packet in the form it will have on the receiver after
field to one, and sends the packet. This ensures the AH calculation
is done on the packet in the form it will have on the receiver after
advancing the routing header. advancing the routing header.
Following the definition of a type 2 routing header in Section 6.4, Following the definition of a type 2 routing header in Section 6.4,
this packet will be routed to the mobile node's care-of address, this packet will be routed to the mobile node's care-of address,
where it will be delivered to the mobile node (the mobile node has where it will be delivered to the mobile node (the mobile node has
associated the care-of address with its network interface). associated the care-of address with its network interface).
Note that following the above conceptual model in an implementation Note that following the above conceptual model in an implementation
creates some additional requirements for path MTU discovery since the creates some additional requirements for path MTU discovery since the
layer that decides the packet size (e.g., TCP and applications using layer that decides the packet size (e.g., TCP and applications using
UDP) needs to be aware of the size of the headers added by the IP UDP) needs to be aware of the size of the headers added by the IP
layer on the sending node. layer on the sending node.
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 is a mobile node that is currently away from home, the packet will be
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
Sections 9.2 and 9.3.1 describe error conditions that lead to a need Section 9.2 and Section 9.3.1 describe error conditions that lead to
to send a Binding Error message. a need to send a Binding Error message.
A Binding Error message is sent to the address that appeared in the A Binding Error message is sent to the address that appeared in the
IPv6 Source Address field of the offending packet. If the Source IPv6 Source Address field of the offending packet. If the Source
Address field does not contain a unicast address, the Binding Error Address field does not contain a unicast address, the Binding Error
message MUST NOT be sent. 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
from the Home Address field in the Home Address destination option of from the Home Address field in the Home Address destination option of
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.
Binding Error messages are subject to rate limiting in the same Binding Error messages are 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
mobile node's home link. Any ICMP error message caused by the mobile node's home link. Any ICMP error message caused by the packet
packet on its way to the mobile node while in the tunnel, will be on its way to the mobile node while in the tunnel, will be
transmitted to the mobile node's home agent. By the definition of transmitted to the mobile node's home agent. By the definition of
IPv6 encapsulation [15], the home agent MUST relay certain ICMP error IPv6 encapsulation [15], the home agent MUST relay certain ICMP error
messages back to the original sender of the packet, which in this messages back to the original sender of the packet, which in this
case is the correspondent node. case is the correspondent node.
Thus, in all cases, any meaningful ICMP error messages caused by Thus, in all cases, any meaningful ICMP error messages caused by
packets from a correspondent node to a mobile node will be returned packets from a correspondent node to a mobile node will be returned
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. correspondent node SHOULD delete this Binding 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:
- The Header Len field in the Mobility Header MUST NOT be less than o The packet MUST NOT include a Home Address destination option.
the length specified in Section 6.1.3.
- 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 material to engage in a return routability procedure, as specified in
in Section 5.2. The correspondent node MUST have a secret Kcn and Section 5.2. The correspondent node MUST have a secret Kcn and a
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:
- The Header Len field in the Mobility Header MUST NOT be less than o The packet MUST NOT include a Home Address destination option.
the length specified in Section 6.1.4.
- 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. Note that the Home Test message is always latter's home address. Note that the Home Test message is always
sent to the home address of the mobile node, even when there is an sent to the home address of the mobile node, even when there is an
existing binding for the mobile node. existing binding for the mobile node.
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 nonce and uses the current
nonce index as the Care-of Nonce Index. It then creates a Care-of nonce index as the Care-of Nonce Index. It then creates a Care-of
Test message (Section 6.1.6) and sends it to the mobile node at the Test message (Section 6.1.6) and sends it to the mobile node at the
latter's care-of address. 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:
- Binding Update o Binding Update
- Binding Refresh Request o Binding Refresh Request
- Binding Acknowledgement
- Binding Error o Binding Acknowledgement
9.5.1. Receiving Binding Updates o Binding Error
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:
- The packet MUST contain a Home Address option with a unicast o The packet MUST contain a unicast routable home address, either in
routable home address, unless the Source Address is the home the Home Address option or in the Source Address, if the Home
address of the mobile node Address option is not present.
- The Header Len field in the Mobility Header is no less than the
length specified in Section 6.1.7.
- 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 Binding Update for the Sequence Number received in the valid previous Binding Update
this home address, if any. for this home address, if any.
This Sequence Number comparison MUST be performed modulo 2**16, This Sequence Number comparison MUST be performed modulo 2**16,
i.e., the number is a free running counter represented modulo i.e., the number is a free running counter represented modulo
65536. A Sequence Number in a received Binding Update is 65536. A Sequence Number in a received Binding Update is
considered less than or equal to the last received number if considered less than or equal to the last received number if its
its value lies in the range of the last received number and the value lies in the range of the last received number and the
preceding 32767 values, inclusive. For example, if the last preceding 32767 values, inclusive. For example, if the last
received sequence number was 15, then messages with sequence received sequence number was 15, then messages with sequence
numbers 0 through 15, as well as 32784 through 65535, would be numbers 0 through 15, as well as 32784 through 65535, would be
considered less than or equal. considered less than or equal.
When the return routability procedure is used to enable the When the return routability procedure is used to enable the
establishment of nonce indices as inputs to the creation of the establishment of nonce indices as inputs to the creation of the
binding key Kbm, the following are also required: binding key Kbm, the following are also required:
- 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 Care-of Nonce Index values in this option MUST be recent enough to
to be recognized by the correspondent node. be recognized by the correspondent node. (Care-of Nonce Index
values are not inspected for requests to delete a binding.)
- The correspondent node MUST re-generate the home keygen token and o The correspondent node MUST re-generate the home keygen token and
the care-of keygen token from the information contained in the the care-of keygen token from the information contained in the
packet. It then generates the binding management key Kbm and packet. It then generates the binding management key Kbm and uses
uses it to verify the authenticator field in the Binding Update it to verify the authenticator field in the Binding Update as
as specified in Section 6.1.7. specified in Section 6.1.7.
When using Kbm for validating the Binding Update, the following are When using Kbm for validating the Binding Update, the following are
required: required:
- The Binding Authorization Data mobility option MUST be present, o The Binding Authorization Data mobility option MUST be present,
and its contents MUST satisfy rules presented in Section 5.2.6. and its contents MUST satisfy rules presented in Section 5.2.6.
Note that a care-of address different from the Source Address MAY Note that a care-of address different from the Source Address MAY
have been specified by including an Alternate Care-of Address have been specified by including an Alternate Care-of Address
mobility option in the Binding Update. When such message is mobility option in the Binding Update. When such a message is
received and the return routability procedure is used as an received and the return routability procedure is used as an
authorization method, the correspondent node MUST verify the authorization method, the correspondent node MUST verify the
authenticator by using the address within the Alternate Care-of authenticator by using the address within the Alternate Care-of
Address in the calculations. Address in the calculations.
- The Binding Authorization Data mobility option MUST be the last o The Binding Authorization Data mobility option MUST be the last
option and MUST NOT have trailing padding. option and MUST NOT have trailing padding.
- The Home Registration (H) bit MUST NOT be set.
If the mobile node sends a sequence number which is not greater than If the mobile node sends a sequence number which is not greater than
the sequence number from the last successful Binding Update, then the the sequence number from the last successful Binding Update, then the
receiving node MUST send back a Binding Acknowledgement with status receiving node MUST send back a Binding Acknowledgement with status
code 135, and the last accepted sequence number in the Sequence code 135, and the last accepted sequence number in the Sequence
Number field of the Binding Acknowledgement. Number field of the Binding Acknowledgement.
If the receiving node no longer recognizes the Home Nonce If the receiving node no longer recognizes the Home Nonce Index
Index value, Care-of Nonce Index value, or both values from the value, Care-of Nonce Index value, or both values from the Binding
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.
Packets carrying Binding Updates that fail to satisfy all of these For packets carrying Binding Updates that fail to satisfy all of
tests for any reason other than insufficiency of the Sequence Number these tests for any reason other than insufficiency of the Sequence
or expired nonce index values MUST be silently discarded. Number or expired nonce index values MUST be 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:
- If the Lifetime specified in the Binding Update is nonzero and o If the Lifetime specified in the Binding Update is nonzero and the
the specified care-of address is not equal to the home address specified care-of address is not equal to the home address for the
for the binding, then this is a request to cache a binding for binding, then this is a request to cache a binding for the mobile
the mobile node. If the Home Registration (H) bit is set in the node. If the Home Registration (H) bit is set in the Binding
Binding Update, the Binding Update is processed according to the Update, the Binding Update is processed according to the procedure
procedure specified in Section 10.3.1; otherwise, it is processed specified in Section 10.3.1; otherwise, it is processed according
according to the procedure specified in Section 9.5.2. to the procedure specified in Section 9.5.2.
- If the Lifetime specified in the Binding Update is zero or the o If the Lifetime specified in the Binding Update is zero or the
specified care-of address matches the home address for the specified care-of address matches the home address for the
binding, then this is a request to delete the mobile node's binding, then this is a request to delete the mobile node's cached
cached binding. The update MUST include a valid home nonce index binding. In this case, the Binding Update MUST include a valid
(the care-of nonce index MUST be ignored by the correspondent home nonce index, and the care-of nonce index MUST be ignored by
node). In this case, generation of the binding management key the correspondent node. The generation of the binding management
depends exclusively on the home keygen token (Section 5.2.5). If key depends then exclusively on the home keygen token (Section
the Home Registration (H) bit is set in the Binding Update, the 5.2.5). If the Home Registration (H) bit is set in the Binding
Binding Update is processed according to the procedure specified Update, the Binding Update is processed according to the procedure
in Section 10.3.2; otherwise, it is processed according to the specified in Section 10.3.2; otherwise, it is processed according
procedure specified in Section 9.5.3. to the procedure specified in Section 9.5.3.
The specified care-of address MUST be determined as follows: The specified care-of address MUST be determined as follows:
- If the Alternate Care-of Address option is present, the care-of o If the Alternate Care-of Address option is present, the care-of
address is the address in that option. address is the address in that option.
- Otherwise, the care-of address is the Source Address field in the o Otherwise, the care-of address is the Source Address field in the
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:
- 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.
- 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. This implies that the mobile node is at packet's IPv6 header. This implies that the mobile node is at
home and is about to perform de-registration. home and is about to perform de-registration.
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 mobile node's binding, for which the Home requests a node to cache a mobile node's binding, for which the Home
Registration (H) bit is not set in the Binding Update. Registration (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 mobile node, or update its existing Binding Binding Cache for this mobile node, or update its existing Binding
Cache entry for this mobile node, if such an entry already exists. Cache entry for this mobile node, 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
skipping to change at page 73, line 47 skipping to change at page 86, line 18
Update is stored by a correspondent node in its Binding Cache entry Update is stored by a correspondent node in its Binding Cache entry
for that mobile node. If the receiving correspondent node has no for that mobile node. If the receiving correspondent node has no
Binding Cache entry for the sending mobile node, it MUST accept any Binding Cache entry for the sending mobile node, it MUST accept any
Sequence Number value in a received Binding Update from this mobile Sequence Number value in a received Binding Update from this mobile
node. node.
The correspondent node MAY refuse to accept a new Binding Cache The correspondent node MAY refuse to accept a new Binding Cache
entry, if it does not have sufficient resources. A new entry MAY entry, if it does not have sufficient resources. A new entry MAY
also be refused if the correspondent node believes its resources are also be refused if the correspondent node believes its resources are
utilized more efficiently in some other purpose, such as serving utilized more efficiently in some other purpose, such as serving
another mobile node with higher amount of traffic. In both cases another mobile node with higher amount of traffic. In both cases the
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 mobile node's binding from its Binding requests a node to delete a mobile node's binding from its Binding
Cache, for which the Home Registration (H) bit is not set in the Cache, for which the Home Registration (H) bit is not set in the
Binding Update. Binding Update.
Any existing binding for the mobile node MUST be deleted. A Binding Any existing binding for the mobile node MUST be deleted. A Binding
Cache entry for the mobile node MUST NOT be created in response to Cache entry for the mobile node MUST NOT be created in response to
receiving the Binding Update. 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 not used again with the particular home and care-of address. If both
both nonces are still valid, the correspondent node has to remember nonces are still valid, the correspondent node has to remember the
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:
- If the Binding Update was silently discarded as described in 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, if the Acknowledge (A) bit set is set in the Binding o If the Acknowledge (A) bit set is set in the Binding Update, a
Update, a Binding Acknowledgement MUST be sent. Binding Acknowledgement MUST be sent. Otherwise, the treatment
depends on the below rule.
- Otherwise, if the node rejects the Binding Update, a Binding
Acknowledgement MUST be sent.
- Otherwise, if the node accepts the Binding Update, a Binding o If the node rejects the Binding Update, a Binding Acknowledgement
MUST be sent. If the node accepts the Binding Update, the Binding
Acknowledgement SHOULD NOT be sent. Acknowledgement SHOULD NOT be sent.
If the node accepts the Binding Update and creates or updates If the node accepts the Binding Update and creates or updates an
an entry for this binding, the Status field in the Binding entry for this binding, the Status field in the Binding
Acknowledgement MUST be set to a value less than 128. Otherwise, the Acknowledgement MUST be set to a value less than 128. Otherwise, the
Status field MUST be set to a value greater than or equal to 128. Status field MUST be set to a value greater than or equal to 128.
Values for the Status field are described in Section 6.1.8 and in the Values for the Status field are described in Section 6.1.8 and in the
IANA registry of assigned numbers [18]. IANA registry of assigned numbers [19].
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), 136 (expired home nonce index), 137 (expired care-of nonce index), or
or 138 (expired nonces), then the message MUST NOT include the 138 (expired nonces) then the message MUST NOT include the Binding
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
If the Source Address is the home address of the mobile node, i.e., Address is the home address of the mobile node, i.e., the Binding
the Binding Update did not contain a Home Address destination option, Update did not contain a Home Address destination option, then the
then the Binding Acknowledgement MUST be sent to that address, Binding Acknowledgement MUST be sent to that address, and the routing
and the routing header MUST NOT be used. Otherwise, the Binding header MUST NOT be used. Otherwise, the Binding Acknowledgement MUST
Acknowledgement MUST be sent using a type 2 routing header which be sent using a type 2 routing header which contains the mobile
contains the mobile node's home address. node's home address.
Entries in a node's Binding Cache MUST be deleted when their lifetime Entries in a node's Binding Cache MUST be deleted when their lifetime
expires. expires.
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 If a Binding Cache entry being deleted is still in active use in
in sending packets to a mobile node, the next packet sent to the sending packets to a mobile node, the next packet sent to the mobile
mobile node will be routed normally to the mobile node's home link. node will be routed normally to the mobile node's home link.
Communication with the mobile node continues, but the tunneling Communication with the mobile node continues, but the tunneling from
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. The Binding Refresh Request recreating the Binding Cache entry. The Binding Refresh Request
message is sent in the same way as any packet addressed to the mobile message is sent in the same way as any packet addressed to the mobile
node (Section 9.3.2). node (Section 9.3.2).
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 provided that rate limitation is applied. The correspondent
node SHOULD stop retransmitting when it receives a Binding Update.