draft-ietf-nemo-basic-support-01.txt   draft-ietf-nemo-basic-support-02.txt 
NEMO Working Group Vijay Devarapalli NEMO Working Group Vijay Devarapalli
INTERNET DRAFT Nokia INTERNET DRAFT Nokia
Category: Standards Track Ryuji Wakikawa Category: Standards Track Ryuji Wakikawa
Expires March 2004 Keio University Expires June 2004 Keio University
Alexandru Petrescu Alexandru Petrescu
Motorola Motorola
Pascal Thubert Pascal Thubert
Cisco Systems Cisco Systems
September 2003 December 2003
Nemo Basic Support Protocol Network Mobility (NEMO) Basic Support Protocol
draft-ietf-nemo-basic-support-01.txt draft-ietf-nemo-basic-support-02.txt
Status of This Memo Status of This Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of Section 10 of RFC2026. of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
skipping to change at page 1, line 38 skipping to change at page 1, line 37
any time. It is inappropriate to use Internet- Drafts as reference any time. It is inappropriate to use Internet- Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at: The list of current Internet-Drafts can be accessed at:
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at: The list of Internet-Draft Shadow Directories can be accessed at:
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
This document describes the Nemo Basic Support protocol to support This document describes the NEMO Basic Support protocol that enables
network mobility as the mobile network attaches to different points mobile networks to attach to different points in the Internet. The
in the Internet. The protocol is based on extensions to Mobile protocol is an extension of Mobile IPv6 and allows for session
IPv6 and allows for session continuity for every node in the mobile continuity for every node in the mobile network as the network moves.
network as the network moves. It also allows every node in the It also allows every node in the mobile network to be reachable while
mobile network to be reachable while moving around. The Mobile moving around. The Mobile Router, which connects the network to the
Router, which connects the network to the Internet, runs the NEMO Internet, runs the NEMO Basic Support protocol with its Home Agent.
Basic Support protocol with its Home Agent. The protocol is designed The protocol is designed in such a way that network mobility is
in such a way that network mobility is transparent to the nodes transparent to the nodes inside the mobile network.
inside the mobile network.
Contents Contents
Status of This Memo 1 Status of This Memo 1
Abstract 1 Abstract 1
1. Introduction 4 1. Introduction 4
2. Terminology 5 2. Terminology 5
3. Overview of the Nemo Protocol 6 3. Overview of the NEMO Protocol 6
4. Message Formats 9 4. Message Formats 9
4.1. Binding Update . . . . . . . . . . . . . . . . . . . . . 9 4.1. Binding Update . . . . . . . . . . . . . . . . . . . . . 9
4.2. Binding Acknowledgement . . . . . . . . . . . . . . . . . 9 4.2. Binding Acknowledgement . . . . . . . . . . . . . . . . . 9
4.3. Mobile Network Prefix Option . . . . . . . . . . . . . . 10 4.3. Mobile Network Prefix Option . . . . . . . . . . . . . . 10
4.4. Mobile Network Prefix Length Option . . . . . . . . . . . 11
5. Mobile Router Operation 13 5. Mobile Router Operation 12
5.1. Data Structures . . . . . . . . . . . . . . . . . . . . . 13 5.1. Data Structures . . . . . . . . . . . . . . . . . . . . . 12
5.2. Sending Binding Updates . . . . . . . . . . . . . . . . . 13 5.2. Sending Binding Updates . . . . . . . . . . . . . . . . . 13
5.3. Receiving Binding Acknowledgements . . . . . . . . . . . 14 5.3. Receiving Binding Acknowledgements . . . . . . . . . . . 13
5.4. Error Processing . . . . . . . . . . . . . . . . . . . . 15 5.4. Error Processing . . . . . . . . . . . . . . . . . . . . 14
5.5. Establishment of Bi-directional Tunnel . . . . . . . . . 16 5.5. Establishment of Bi-directional Tunnel . . . . . . . . . 15
5.6. Neighbour Discovery for Mobile Router . . . . . . . . . . 17 5.6. Neighbor Discovery for Mobile Router . . . . . . . . . . 16
5.7. Multicast Groups for Mobile Router . . . . . . . . . . . 17 5.7. Multicast Groups for Mobile Router . . . . . . . . . . . 16
5.8. Returning Home . . . . . . . . . . . . . . . . . . . . . 16
6. Home Agent Operation 18 6. Home Agent Operation 18
6.1. Data Structures . . . . . . . . . . . . . . . . . . . . . 18 6.1. Data Structures . . . . . . . . . . . . . . . . . . . . . 18
6.1.1. Binding Cache . . . . . . . . . . . . . . . . . . 18 6.1.1. Binding Cache . . . . . . . . . . . . . . . . . . 18
6.1.2. Prefix Table . . . . . . . . . . . . . . . . . . 18 6.1.2. Prefix Table . . . . . . . . . . . . . . . . . . 18
6.2. Mobile Network Prefix Registration . . . . . . . . . . . 19 6.2. Mobile Network Prefix Registration . . . . . . . . . . . 19
6.3. Advertising Mobile Network Reachability . . . . . . . . . 20 6.3. Advertising Mobile Network Reachability . . . . . . . . . 20
6.4. Establishment of Bi-directional Tunnel . . . . . . . . . 21 6.4. Establishment of Bi-directional Tunnel . . . . . . . . . 20
6.5. Forwarding Packets . . . . . . . . . . . . . . . . . . . 21 6.5. Forwarding Packets . . . . . . . . . . . . . . . . . . . 21
6.6. Sending Binding Acknowledgements . . . . . . . . . . . . 22 6.6. Sending Binding Acknowledgements . . . . . . . . . . . . 21
6.7. Mobile Network Prefix De-Registration . . . . . . . . . . 22 6.7. Mobile Network Prefix De-Registration . . . . . . . . . . 22
7. Support for Dynamic Routing Protocols 23 7. Modifications to Dynamic Home Agent Discovery 23
7.1. Modified Dynamic Home Agent Discovery Request . . . . . . 23
7.2. Modified Dynamic Home Agent Discovery Reply . . . . . . . 23
7.3. Modified Home Agent Information Option . . . . . . . . . 24
8. Security Considerations 25 8. Support for Dynamic Routing Protocols 25
9. IANA Considerations 25 9. Security Considerations 27
10. Contributors 25 10. IANA Considerations 28
11. Acknowledgements 26 11. Contributors 28
A. Examples of Operation 28 12. Acknowledgements 28
B. Changes from Previous Version 31 A. Examples of NEMO Basic Support Operation 31
Addresses 32 B. Changes from Previous Version 34
1. Introduction 1. Introduction
This document describes protocol extensions to Mobile IPv6 (MIPv6) This document describes protocol extensions to Mobile IPv6 (MIPv6)
[1] to enable support for network mobility. The extensions provide [1] to enable support for network mobility. The extensions are
backward compatibility with Mobile IPv6, and in particular, a Nemo backward compatible with Mobile IPv6. In particular, a NEMO
compliant Home Agent can operate as a MIPv6 Home Agent as well. compliant Home Agent can operate as a Mobile IPv6 Home Agent as well.
The Nemo Basic Support works in such a way that session continuity is The NEMO Basic Support works in such a way that session continuity is
ensured for all the nodes in the mobile network even as the Mobile ensured for all the nodes in the mobile network even as the Mobile
Router changes its point of attachment to the Internet. It also Router changes its point of attachment to the Internet. It also
provides connectivity and reachability for all nodes in the mobile provides connectivity and reachability for all nodes in the mobile
network as the network moves. The solution supports both Local Fixed network as the network moves. The solution supports both mobile
Nodes [8] and Mobile Nodes in the Mobile Network. nodes and hosts that do not support mobility in the mobile network.
Within the context of this document, the definition of a Mobile Within the context of this document, the definition of a Mobile
Router extends that of a Mobile IPv6 [1] Mobile Node, by adding Router extends that of a Mobile IPv6 [1] Mobile Node, by adding
the capability of routing between its point of attachment (Care-of the capability of routing between its point of attachment (Care-of
Address) and a subnet which moves with the Mobile Router. Address) and a subnet which moves with the Mobile Router.
The solution described in this document requires setting up a The solution described in this document requires setting up a
bi-directional tunnel between the Mobile Router and its Home Agent. bi-directional tunnel between the Mobile Router and its Home Agent.
This tunnel is set up when the Mobile Router sends a successful This tunnel is set up when the Mobile Router sends a successful
Binding Update to its Home Agent, informing the Home Agent of its Binding Update to its Home Agent, informing the Home Agent of its
current point of attachment. current point of attachment.
All traffic between the nodes in the Mobile Network and Correspondent All traffic between the nodes in the mobile network and Correspondent
Nodes passes through the Home Agent. This document does not describe Nodes passes through the Home Agent. This document does not describe
how to route optimize this traffic. route optimization of this traffic.
The terminology document [8] describes Nested Mobility as a scenario The terminology document [9] describes Nested Mobility as a scenario
where a Mobile Router allows another Mobile Router to attach to its where a Mobile Router allows another Mobile Router to attach to its
mobile network. There could be arbitrary levels of nested mobility. mobile network. There could be arbitrary levels of nested mobility.
The operation of each Mobile Router remains the same whether the The operation of each Mobile Router remains the same whether the
Mobile Router attaches to another Mobile Router or to a fixed Access Mobile Router attaches to another Mobile Router or to a fixed Access
Router on the Internet. The solution described here does not place Router on the Internet. The solution described here does not place
any restriction on the number of levels for nested mobility. But it any restriction on the number of levels for nested mobility. But it
should be noted that this might introduce significant overhead on should be noted that this might introduce significant overhead on the
the data packets as each level of nestedness introduces another IPv6 data packets as each level of nesting introduces another IPv6 header
header encapsulation. encapsulation.
2. Terminology 2. 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].
There is a separate NEMO terminology document [8], which defines the Network Mobility related terminology is defined in [8] [9]. This
terms related to Network Mobility used in the document. document in addition defines the following terms.
Mobile Network Prefix
An IPv6 prefix that is delegated to a Mobile
Router and advertised in the mobile network. There could
be more than one Mobile Network Prefix being advertised in
a mobile network.
Prefix Table Prefix Table
It is a list of a Mobile Network Prefixes indexed It is a list of Mobile Network Prefixes indexed by
by the Home Address of a Mobile Router. The prefix table the Home Address of a Mobile Router. The prefix table is
is managed by the Home Agent and is used by the Home Agent managed by the Home Agent and is used by the Home Agent
to determine which Mobile Network Prefixes are owned to determine which Mobile Network Prefixes belong to a
a particular Mobile Router. This is an optional data particular Mobile Router.
structure.
3. Overview of the Nemo Protocol 3. Overview of the NEMO Protocol
A Mobile Network is a network segment or subnet which can move A Mobile Network is a network segment or subnet which can move and
and attach to arbitrary points in the Internet. A Mobile Network attach to arbitrary points in the Internet. A mobile network can
does not allow any transit traffic and can only be accessed via only be accessed via specific gateways called Mobile Routers that
specific gateways called Mobile Routers that manage its movement. manage its movement. Mobile networks have atleast one Mobile Router
A Mobile Router does not distribute the Mobile Network routes to serving them. A Mobile Router does not distribute the mobile network
the infrastructure at its point of attachment (i.e. in the visited routes to the infrastructure at its point of attachment (i.e. in the
network). Instead, it maintains a bidirectional tunnel to a Home visited network). Instead, it maintains a bidirectional tunnel to a
Agent that advertises an aggregation of Mobile Networks to the Home Agent that advertises an aggregation of mobile networks to the
infrasructure. The Mobile Router is also the default gateway for the infrasructure. The Mobile Router is also the default gateway for the
Mobile Network. mobile network.
A Mobile Network can also consist of multiple and nested subnets. A A mobile network can also consist of multiple and nested subnets. A
router with no support for mobility may be permanently attached to router with no support for mobility may be permanently attached to
a Mobile Network for local distribution. Also, Mobile Routers may a mobile network for local distribution. Also, Mobile Routers may
be attached to Mobile Networks owned by different Mobile Routers and be attached to mobile networks owned by different Mobile Routers and
form a graph. In particular, with Basic Nemo Support, each Mobile form a graph. In particular, with Basic NEMO Support, each Mobile
Router is attached to another Mobile Network by a single interface, Router is attached to another mobile network by a single interface,
and if loops are avoided, the graph is a tree. and if loops are avoided, the graph is a tree.
A Mobile Router has an unique Home Address through which it is always A Mobile Router has an unique Home Address through which it is
reachable. The Home Address is configured from a prefix that is reachable when it is registered with its Home Agent. The Home
aggregated and advertised by its Home Agent. The prefix could either Address is configured from a prefix that is aggregated and advertised
be the prefix advertised on the home link or the prefix delegated to by its Home Agent. The prefix could either be the prefix advertised
the Mobile Router. The Mobile Router can have more than one Home on the home link or the prefix delegated to the Mobile Router.
Address if there are multiple prefixes in the home link. The Mobile The Mobile Router can have more than one Home Address if there
Router also advertises one or more prefixes in the mobile network are multiple prefixes in the home link. The Mobile Router also
attached to it. The actual mechanism for allocating these Mobile advertises one or more prefixes in the mobile network attached to it.
Network Prefixes is outside the scope of this specification. The actual mechanism for assigning these prefixes to a given Mobile
Router is outside the scope of this specification.
When the Mobile Router moves away from the home link and attaches When the Mobile Router moves away from the home link and attaches to
to a new access router, it acquires a Care-of Address from the a new access router, it acquires a Care-of Address from the visited
visited link. The Mobile Router at any time can appear and behave link. The Mobile Router can at any time act either as a Mobile Host
as a Mobile Host or a Mobile Router. If the Mobile Router wants or a Mobile Router. In either case, as soon as the Mobile Router
connectivity, reachability and session continuity for nodes in the acquires a Care-of Address, it immediately sends a Binding Update to
Mobile Network, it acts as a Mobile Router. In either case, as soon its Home Agent as described in [1]. When the Home Agent receives
as the Mobile Router acquires a Care-of Address, it immediately sends this Binding Update it creates a binding cache entry binding the
a Binding Update to its Home Agent as described in [1]. When the Mobile Router's Home Address to its Care-of address at the current
Home Agent receives this Binding Update it creates a binding cache point of attachment.
entry binding the Mobile Router's Home Address to its Care-of address
at the current point of attachment.
If the Mobile Router wishes to act as a Mobile Router and provide If the Mobile Router wishes to act as a Mobile Router and provide
connectivity to nodes in the Mobile Network, it indicates this to connectivity to nodes in the mobile network, it indicates this to the
the Home Agent by setting a flag 'R' in the Binding Update. It MAY Home Agent by setting a flag (R) in the Binding Update. It MAY also
also include information about the Mobile Network Prefix in the include information about the Mobile Network Prefix in the Binding
Binding Update using one of the modes described in section 5.2, so Update using one of the modes described in Section 5.2, so that the
that the Home Agent can forward packets meant for nodes in the mobile Home Agent can forward packets meant for nodes in the mobile network
network to the Mobile Router. Two new Mobility Header Options are to the Mobile Router. A new Mobility Header Option is described in
described in this document to carry prefix information. These new this document to carry prefix information. This option is described
options are described in section 4.3 and section 4.4. If the Mobile in Section 4.3. If the mobile network has more than one IPv6 prefix
Network has more than one IPv6 prefix and wants the Home Agent to and wants the Home Agent to setup forwarding for all these prefixes,
setup forwarding for all these prefixes, it includes multiple prefix it includes multiple prefix information options in a single Binding
information options in a single Binding Update. The Home Agent sets Update. The Home Agent sets up forwarding for each of these prefixes
up forwarding for each of these prefixes to the Mobile Router's to the Mobile Router's Care-of Address. In some scenarios the Home
Care-of Address. In some scenarios the Home Agent already knows Agent already knows which prefixes belong to a Mobile Router. In
which prefixes are owned by a Mobile Router. In these scenarios, the these scenarios, the Mobile Router does not include any prefix
Mobile Router does not include any prefix information in the Binding information in the Binding Update. The Home Agent sets up forwarding
Update. The Home Agent sets up forwarding for all prefixes owned by for all prefixes owned by the Mobile Router, when it receives a
the Mobile Router, when it receives a Binding Update from the mobile Binding Update from the mobile router with the router flag (R) set.
router with the router flag 'R' set.
The Home Agent acknowledges the Binding Update by sending a Binding The Home Agent acknowledges the Binding Update by sending a Binding
Acknowledgement to the Mobile Router. A positive acknowledgement Acknowledgement to the Mobile Router. A positive acknowledgement
means that the HA has set up forwarding for the Mobile Network. means that the Home Agent has set up forwarding for the mobile
Once the binding process completes, a bi-directional tunnel is network. Once the binding process completes, a bi-directional tunnel
established between the Home Agent and the Mobile Router. The tunnel is established between the Home Agent and the Mobile Router. The
end points are Mobile Router's Care-of Address and the Home Agent's tunnel end points are Mobile Router's Care-of Address and the Home
address. If a packet with a source address belonging to the Mobile Agent's address. If a packet with a source address belonging to
Network Prefix is received from the Mobile Network, the Mobile Router the Mobile Network Prefix is received from the mobile network, the
reverse-tunnels the packet to the Home Agent through this tunnel. Mobile Router reverse-tunnels the packet to the Home Agent through
This reverse-tunneling is done by using IP-in-IP encapsulation [3]. this tunnel. This reverse-tunneling is done by using IP-in-IP
The Home Agent decapsulates this packet and forwards it to the encapsulation [3]. The Home Agent decapsulates this packet and
Correspondent Node. The Mobile Router is however free to use route forwards it to the Correspondent Node. For traffic originated by
optimization as described in [1] for packet originated by the Mobile itself, the Mobile Router can use either reverse tunneling or route
Router itself. optimization as specified in [1].
When a data packet is sent by a Correspondent Node to a node in the When a data packet is sent by a Correspondent Node to a node in the
Mobile Network, it gets routed to the Home Agent which currently mobile network, it gets routed to the Home Agent which currently
has the binding for the Mobile Router. It is expected that the has the binding for the Mobile Router. It is expected that the
Mobile Router's network prefix would be aggregated at the Home Agent, Mobile Router's network prefix would be aggregated at the Home Agent,
which advertises the resulting aggregation. Alternatively, the Home which advertises the resulting aggregation. Alternatively, the Home
Agent may receive the data packets meant for the Mobile Network Agent may receive the data packets destined to the mobile network
by advertising routes to the Mobile Network prefix. The actual by advertising routes to the Mobile Network Prefix. The actual
mechanism by which these routes are advertised is outside the scope mechanism by which these routes are advertised is outside the scope
of this document. When the Home Agent receives a data packet meant of this document. When the Home Agent receives a data packet meant
for a node in the mobile network, it tunnels the packet to Mobile for a node in the mobile network, it tunnels the packet to Mobile
Router's current Care-of address. The Mobile Router decapsulates Router's current Care-of address. The Mobile Router decapsulates
the packet and forwards it onto the interface where the Mobile the packet and forwards it onto the interface where the mobile
Network is connected. The Mobile Router before decapsulating the network is connected. The Mobile Router before decapsulating the
tunneled packet, has to check if the Source address on the outer IPv6 tunneled packet, has to check if the Source address on the outer IPv6
header is the Home Agent's address. It also has to make sure the header is the Home Agent's address. It also has to make sure the
destination address on the inner IPv6 header belongs to one of its destination address on the inner IPv6 header belongs to one of its
Mobile Network Prefixes before forwarding the packet to the Mobile Mobile Network Prefixes before forwarding the packet to the mobile
Network. network.
The Mobile Network could consist of nodes which are Local Fixed The mobile network could consist of nodes that do not support
Nodes, Local Mobile Nodes and Visiting Mobile Nodes [8]. The mobility and nodes that support mobility. A node in the mobile
protocol described here ensures complete transparency of network network can also be a fixed or a mobile router. The protocol
mobility to the Local Fixed Nodes. Visiting Mobile Nodes are those described here ensures complete transparency of network mobility to
nodes which are Mobile Nodes as described in Mobile IPv6. Visiting the nodes in the mobile network. Mobile Nodes that attach to the
Mobile Nodes treat the Mobile Network as just a normal IPv6 access mobile network treat it as a normal IPv6 access network and run the
network and run the Mobile IPv6 protocol. Mobile IPv6 protocol.
It is also possible for the Mobile Router and the Home Agent to run It is also possible for the Mobile Router and the Home Agent to run
a routing protocol through the bi-directional tunnel. In that case, a routing protocol through the bi-directional tunnel. In that case,
the Mobile Router need not include prefix information in the Binding the Mobile Router need not include prefix information in the Binding
Update. Instead the Home Agent uses the routing protocol updates to Update. Instead the Home Agent uses the routing protocol updates to
setup forwarding for the Mobile Network. When running the routing setup forwarding for the mobile network. When running the routing
protocol it is required that the bi-directional tunnel be treated as protocol it is required that the bi-directional tunnel be treated as
a tunnel interface. The tunnel interface is included as the list of a tunnel interface. The tunnel interface is included as the list of
interfaces on which routing protocol is active. The Mobile Router interfaces on which routing protocol is active. The Mobile Router
should be configured not to run the routing protocol on its egress should be configured not to run the routing protocol on its egress
interface when it is away from the home link. interface when it is away from the home link.
Finally, the Home Agent may be configured with static routes to the Finally, the Home Agent may be configured with static routes to the
Mobile Network Prefix via the Mobile Router's Home Address. In that Mobile Network Prefix via the Mobile Router's Home Address. In that
case, the routes are set independently of the binding flows and the case, the routes are set independently of the binding flows and the
returning Home of a Mobile Router. The benefit is that such movement returning Home of a Mobile Router. The benefit is that such movement
does not induce any additional signalling in the form of routing does not induce any additional signalling in the form of routing
updates in the Home Network. The drawback of that model is that the updates in the Home Network. The drawback of that model is that the
routes are present even if the related Mobile Routers that are not routes are present even if the related Mobile Routers that are not
reachable (at Home or bound) at a given point of time. reachable (at Home or bound) at a given point of time.
4. Message Formats 4. Message Formats
4.1. Binding Update 4.1. Binding Update
A new flag `R' is included in the Binding Update to indicate to the A new flag (R) is included in the Binding Update to indicate to the
Home Agent if the Binding Update is coming from a Mobile Router Home Agent if the Binding Update is coming from a Mobile Router
and not from a mobile node. The rest of the Binding Update format and not from a mobile node. The rest of the Binding Update format
remains the same as defined in [1]. remains the same as defined in [1].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # | | Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|H|L|K|R| Reserved | Lifetime | |A|H|L|K|R| Reserved | Lifetime |
skipping to change at page 9, line 39 skipping to change at page 9, line 39
The Mobile Router Flag is set to indicate to the Home Agent The Mobile Router Flag is set to indicate to the Home Agent
that the Binding Update is from a Mobile Router. If the flag that the Binding Update is from a Mobile Router. If the flag
is set to 0, the Home Agent assumes that the Mobile Router is is set to 0, the Home Agent assumes that the Mobile Router is
just behaving as a Mobile Node, and MUST NOT forward packets just behaving as a Mobile Node, and MUST NOT forward packets
destined for the mobile network to the Mobile Router. destined for the mobile network to the Mobile Router.
Mobility Options Mobility Options
Variable length field which can include zero or more mobility Variable length field which can include zero or more mobility
options. This document defines two new mobility options in options. This document defines a new mobility option in
addition to what is defined in [1]. The receiver MUST skip and addition to what is defined in [1].
ignore any options which it does not understand.
For a description of the other fields in the message, see [1].
4.2. Binding Acknowledgement 4.2. Binding Acknowledgement
There is no change in the Binding Acknowledgement format from what A new flag (R) is included in the Binding Acknowledgement to indicate
is used in Mobile IPv6 [1]. However, this document introduces the that the Home Agent which processed the corresponding Binding Update
following new status values for the binding acknowledgement. supports Mobile Routers. The flag is set only if the corresponding
Binding Update had the Mobile Router flag (R) set to 1. The rest of
the Binding Acknowledgement format remains the same as defined in
[1].
Status 0 1 2 3
2 Mobile Router Binding Update accepted 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status |K|R| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Mobile Router Flag (R)
The Mobile Router Flag is set to indicate that the Home Agent
which processed the Binding Update supports Mobile Routers. It
is set to 1 only if the corresponding Binding Update had the
Mobile Router flag set to 1.
For a description of the other fields in the message, see [1].
This document also introduces the following new Binding
Acknowledgement status values.
140 Mobile Router Operation not permitted 140 Mobile Router Operation not permitted
141 Invalid Prefix 141 Invalid Prefix
142 Not Authorized for Prefix 142 Not Authorized for Prefix
143 Forwarding Setup failed 143 Forwarding Setup failed
Status values less than 128 indicate that the Binding Update was Status values less than 128 indicate that the Binding Update was
processed successfully by the receiving nodes. Values greater than processed successfully by the receiving nodes. Values greater than
128 indicate that the Binding Update was rejected by the receiving 128 indicate that the Binding Update was rejected by the Home Agent.
node.
4.3. Mobile Network Prefix Option 4.3. Mobile Network Prefix Option
The Mobile Network Prefix Option is included in the Binding Update The Mobile Network Prefix Option is included in the Binding Update
to indicate to the Home Agent the prefix information for the mobile to indicate to the Home Agent the prefix information for the mobile
network. There could be multiple Mobile Network Prefix Options network. There could be multiple Mobile Network Prefix Options
if the Mobile Router has more than one IPv6 prefix in the Mobile if the Mobile Router has more than one IPv6 prefix in the mobile
Network and wants the Home Agent to forward packets for each of these network and wants the Home Agent to forward packets for each of these
prefixes to the Mobile Router's current location. prefixes to the Mobile Router's current location.
The Mobile Network Prefix Option has an alignment requirement of The Mobile Network Prefix Option has an alignment requirement of
8n+4. Its format is as follows. 8n+4. 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 | Length | Reserved | Prefix Length | | Type | Length | Reserved | Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 11, line 23 skipping to change at page 12, line 5
Prefix Length Prefix Length
8 bit unsigned integer indicating the prefix length of the IPv6 8 bit unsigned integer indicating the prefix length of the IPv6
prefix contained in the option. prefix contained in the option.
Mobile Network Prefix Mobile Network Prefix
A 16 byte field contains the Mobile Network Prefix. A 16 byte field contains the Mobile Network Prefix.
4.4. Mobile Network Prefix Length Option
The Mobile Network Prefix Length Option can be used by the Mobile
Router if the Mobile Network Prefix can be deduced from the Home
Address of the Mobile Router. If there is only one Mobile Network
Prefix owned by the Mobile Router, using this option helps in
saving 16 bytes in the Binding Update by not including the prefix
information.
There can only be one instance of this option in a Binding Update.
The Mobile Network Prefix Option cannot be present in the Binding
Update if this option is present.
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 | Length | Reserved | Prefix Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBA
Length
8 bit unsigned integer indicating the length in octets of the
option excluding the type and length field. Set to 2.
Reserved
This field is unused for now. The value MUST be initialized to
zero by the sender, and MUST be ignored by the receiver.
Prefix Length
8 bit unsigned integer indicating the prefix length of the IPv6
prefix from which the Home Address included in the Binding
Update was configured.
5. Mobile Router Operation 5. Mobile Router Operation
Mobile Router operation is derived largely from the combined Mobile Router operation is derived largely from the combined
behaviors of a Host, of a Router [6], and of a Mobile Node [1] (also behaviors of a Host, of a Router [6], and of a Mobile Node [1].
please see definition of a Mobile Host in [8]).
A Mobile Node can act in two different ways: (1) as a Mobile Host A Mobile Node can act in two different ways: (1) as a Mobile Host
(in which case the Mobile IPv6 Home Agent doesn't maintain any prefix (in which case the Mobile IPv6 Home Agent doesn't maintain any prefix
information related to the Mobile Host's Home Address, but does information related to the Mobile Host's Home Address, but does
maintain a binding cache entry related to the Mobile Host's Home maintain a binding cache entry related to the Mobile Host's Home
Address) and (2) as a Mobile Router (in which case, in addition to Address) and (2) as a Mobile Router (in which case, in addition to
maintaining the binding cache entry corresponding to the Mobile maintaining the binding cache entry corresponding to the Mobile
Router Home Address, the Mobile IPv6 Home Agent also maintains Router Home Address, the Mobile IPv6 Home Agent also maintains
forwarding information related to prefixes assigned to the mobile forwarding information related to prefixes assigned to the mobile
network). The distinction between the the two modes is represented network). The distinction between the the two modes is represented
by the value of the Mobile Router flag 'R'. by the value of the Mobile Router flag (R).
A Mobile Router MUST implement all requirements for IPv6 Mobile
Nodes, Section 8.5 in [1]. However if a Mobile Router is not
expected to initiate sessions of its own and behaves purely as a
router serving the mobile network most of the time, then the Route
Optimization functionality MAY be implemented.
5.1. Data Structures 5.1. Data Structures
Like a Mobile Host, a Mobile Router also maintains a Binding Update Like a Mobile Host, a Mobile Router also maintains a Binding Update
List, described in section 11.1 of Mobile IPv6 specification[1]. The List, described in Section 11.1 of Mobile IPv6 specification[1]. The
Binding Update list is a conceptual data structure which records Binding Update list is a conceptual data structure which records
information that is sent in the Binding Updates. There is one entry information that is sent in the Binding Updates. There is one entry
per each destination that the Mobile Router is currently sending per each destination that the Mobile Router is currently sending
Binding Updates to. Binding Updates to.
This document introduces a new Prefix Information field in the This document introduces a new Prefix Information field in the
Binding Update list structure. This field is used to store any Binding Update list structure. This field is used to store any
prefix information that the Mobile Router includes in the Binding prefix information that the Mobile Router includes in the Binding
Update. If the Mobile Router sets the Mobile Router flag 'R' in the Update. If the Mobile Router sets the Mobile Router flag (R) in the
Binding Update, but does not include any prefix information in it Binding Update, but does not include any prefix information in it
(implicit mode), this field is set to null. this field is set to null. The Mobile Router does not include prefix
information in the Binding Update in the implicit mode or when it
runs a dynamic routing protocol with its Home Agent.
Similar to a Mobile Host, a Mobile Router stores the information Similar to a Mobile Host, a Mobile Router stores the information
regarding status of flags of the Binding Update, in the corresponding regarding status of flags of the Binding Update, in the corresponding
Binding Update List entry. This document introduces a new mobile Binding Update List entry. This document introduces a new mobile
router flag 'R' for this entry. The status of this flag is stored in router flag (R) for this entry. The status of this flag is stored in
the Binding Update list whenever a Binding Update is sent. the Binding Update list whenever a Binding Update is sent.
A Mobile Router also maintains a Home Agent list populated according A Mobile Router also maintains a Home Agent list populated according
to the same procedure as a Mobile Host. to the same procedure as a Mobile Host.
5.2. Sending Binding Updates 5.2. Sending Binding Updates
A Mobile Router sends Binding Updates to its Home Agent according to A Mobile Router sends Binding Updates to its Home Agent as described
the same procedures that a Mobile Host uses. The Mobile Router uses in [1]. It uses one of the following modes to instruct the Home
one of the following modes to instruct the Home Agent to determine Agent to determine the prefixes that belong to the Mobile Router. In
the prefixes owned by the Mobile Router. In all three modes, the all the modes, the Mobile Router sets the Mobile Router flag (R).
Mobile Router sets the Mobile Router flag 'R'.
Implicit: Implicit:
In this mode, the Mobile Router does not include either a In this mode, the Mobile Router does not include either a
Mobile Network Prefix Option or a Mobile Network Prefix Length Mobile Network Prefix Option or a Mobile Network Prefix Length
Option in the Binding Update (but it does include the Home Option in the Binding Update (but it does include the Home
Address Option in the Destination Options header, as all Mobile Address Option in the Destination Options header, as all Mobile
Hosts do). The Home Agent can use any mechanism (not defined Hosts do). The Home Agent can use any mechanism (not defined
in this document) to determine the Mobile Network Prefix(es) in this document) to determine the Mobile Network Prefix(es)
owned by the Mobile Router and setup forwarding for the Mobile owned by the Mobile Router and setup forwarding for the mobile
Network. One example would be manual configuration at the network. One example would be manual configuration at the
Home Agent mapping the Mobile Router's Home Address to the Home Agent mapping the Mobile Router's Home Address to the
information required for setting up forwarding for the Mobile information required for setting up forwarding for the mobile
Network. network.
Explicit Network: Explicit:
In this mode, the Mobile Router includes one or more Mobile In this mode, the Mobile Router includes one or more Mobile
Network Prefix Options in the Binding Update. These options Network Prefix Options in the Binding Update. These options
contain information about the Mobile Network Prefix(es) contain information about the Mobile Network Prefix(es)
configured on the mobile network. configured on the mobile network.
Explicit Prefix Length: A Mobile Router MUST implement atleast one mode and MAY implement
both modes. If the Mobile Router flag is set, Home Registration flag
In this mode, the Mobile Router instructs the Home Agent to (H) MUST be set.
derive the Mobile Network Prefix by using: (1) the Home
Address in the Home Address Option carried in the Destination
Options header of the same packet that carries the Mobility
Header containing this Binding Update and (2) the prefix length
carried in the Mobile Network Prefix Length Option. In this
case, Mobile Router includes one and only one Mobile Network
Prefix Length Option. It MUST NOT include a Mobile Network
Prefix Option if this method is used.
If the Mobile Router flag is set, Home Registration flag 'H' MUST be
set.
5.3. Receiving Binding Acknowledgements 5.3. Receiving Binding Acknowledgements
The Mobile Router receives Binding Acknowledgements from the The Mobile Router receives Binding Acknowledgements from the Home
Home Agent, corresponding to the Binding Updates it sent. If the Agent, corresponding to the Binding Updates it sent. If the Binding
Binding Acknowledgement status is set to '2' (Mobile Router Binding Acknowledgement status is set to '0' (Binding Update accepted) and
Update accepted), the Mobile Router assumes that the Home Agent has the Mobile Router flag (R) is set to 1, the Mobile Router assumes
successfully processed the Binding Update and has set up forwarding that the Home Agent has successfully processed the Binding Update
for the Mobile Network.The Mobile Router can then start using the and has set up forwarding for the mobile network. The Mobile Router
bi-directional tunnel for reverse tunneling traffic from the mobile can then start using the bi-directional tunnel for reverse tunneling
network. traffic from the mobile network. If the Mobile Router flag (R) is
not set, then the Mobile Router concludes that its current Home
Agent does not support Mobile Routers and performs Dynamic Home
Agent Discovery again to discover Home Agents which support Mobile
Routers. Additional the Mobile Router MUST also de-register with the
Home Agent which did not support Mobile Routers before attempting
registration with another Home Agent.
5.4. Error Processing 5.4. Error Processing
If the Binding Acknowledgement status is set to a value between 128 If the Binding Acknowledgement status is set to a value between 128
and 140, the Mobile Router takes necessary actions as described in and 140, the Mobile Router takes necessary actions as described in
the Mobile IPv6 specification [1]. the Mobile IPv6 specification [1].
If the Binding Acknowlegement status is set to '0' (Binding Update
accepted), the Mobile Router concludes that the Home Agent which
processed the Binding Update is a MIPv6 Home Agent that has not
implemented support for Mobile Routers. It should send a similar
Binding Update to another Home Agent on the link. If no Home Agent
replies positively then the Mobile Router MUST refrain from sending
any Binding Update with the Mobile Router flag set to any home agent
on the home link and log the information.
If the Mobile Router sent a Binding Update to the Home Agent in If the Mobile Router sent a Binding Update to the Home Agent in
implicit mode (i.e. the prefix field in the Binding Update list implicit mode (i.e. the prefix field in the Binding Update list
entry is null) then the Mobile Router interprets only the error entry is null) then the Mobile Router interprets only the error
status '140' (Mobile Router Operation not permitted) and '143' status '140' (Mobile Router Operation not permitted) and '143'
(Forwarding Setup failed) For this Binding Update, the Mobile Router (Forwarding Setup failed). For this Binding Update, the Mobile
MUST discard Binding Acknowledgements with codes '141' and '142'. Router MUST discard Binding Acknowledgements with codes '141' and
'142'.
For the same Binding Update, if the status is '140', then the Mobile For the same Binding Update, if the status is '140', then the Mobile
Router should send a similar Binding Update (implicit mode) to Router should send a similar Binding Update (implicit mode) to
another Home Agent on the same home link. If no Home Agent replies another Home Agent on the same home link. If no Home Agent replies
positively then the Mobile Router MUST refrain from sending any positively then the Mobile Router MUST refrain from sending any
Binding Update with the Mobile Router flag set to any Home Agent on Binding Update with the Mobile Router flag set to any Home Agent on
the home link, and log the information. the home link, and log the information.
For the same Binding Update, if the status is '143', then the Mobile For the same Binding Update, if the status is '143', then the Mobile
Router should send a similar Binding Update (implicit mode) to Router should send a similar Binding Update (implicit mode) to
another Home Agent on the same home link. If no Home Agent replies another Home Agent on the same home link. If no Home Agent replies
positively then Mobile Router SHOULD refrain from sending this positively then Mobile Router SHOULD refrain from sending this
Binding Update to any Home Agent on the home link, and MAY send Binding Update to any Home Agent on the home link, and MAY send
Binding Updates in another mode (e.g. explicitly include a prefix) Binding Updates in another mode (e.g. explicitly include a prefix)
to a Home Agent on the same home link. to a Home Agent on the same home link.
If the Mobile Router sent a Binding Update to Home Agent in any other If the Mobile Router sent a Binding Update to Home Agent in explict
mode than implicit mode (i.e. the prefix field in the Binding Update mode then the Mobile Router interprets only the error status
list entry is not null) then the Mobile Router interprets only the '141' (Invalid Prefix) and '142' (Not Authorized for Prefix).
error status '141' (Invalid Prefix) and '142' (Not Authorized for For this Binding Update, the Mobile Router MUST discard Binding
Prefix). For this Binding Update, the Mobile Router MUST discard Acknowledgements with codes '140' and '143'.
Binding Acknowledgements with codes '140' and '143'.
For the same Binding Update, if the status is set to '141', then the For the same Binding Update, if the status is set to '141', then the
Mobile Router should send a similar Binding Update (same explicit Mobile Router should send a similar Binding Update to another Home
prefix(es) or prefix lengths) to another Home Agent on the same home Agent on the same home link. If no Home Agent replies positively
link. If no Home Agent replies positively then Mobile Router SHOULD then Mobile Router SHOULD refrain from sending this Binding Updates
refrain from sending this Binding Updates to any Home Agent on the to any Home Agent on the home link. At this point, Mobile Router MAY
home link. At this point, Mobile Router MAY try to obtain and own a try to obtain and own a prefix by the same means that it initially
prefix by the same means that it initially got attributed the Invalid got assigned the current Mobile Network Prefix. Alternatively,
Prefix in question. Alternatively, Mobile Router MAY send Binding Mobile Router MAY send Binding Updates in another mode (e.g.
Updates in another mode (e.g. implicit mode) to a Home Agent on the implicit mode) to a Home Agent on the same home link.
same home link.
For the same Binding Update, if the status is set to '142', then the For the same Binding Update, if the status is set to '142', then the
Mobile Router should send a similar Binding Update (same explicit Mobile Router should send a similar Binding Update to another Home
prefix(es) or prefix lens) to another Home Agent on the same home Agent on the same home link. If no Home Agent replies positively
link. If no Home Agent replies positively then Mobile Router SHOULD then Mobile Router SHOULD refrain from sending this Binding Updates
refrain from sending this Binding Updates to any Home Agent on the to any Home Agent on the home link. Additionally, the Home Agent
home link. Additionally, the Home Agent MUST stop advertising MUST stop advertising the respective prefix(es) in the mobile network
the respective prefix(es) in the mobile network with associated with associated Router Advertisements, and modify its own forwarding
Router Advertisements, and modify its own forwarding information information accordingly. Following this, the Mobile Router MAY send
accordingly. Following this, the Mobile Router MAY send Binding Binding Updates in another mode (e.g. implicit) to a Home Agent on
Updates in another mode (e.g. implicit) to a Home Agent on the same the same home link.
home link.
If at the end of this Error Processing procedure the Mobile Router If at the end of this Error Processing procedure the Mobile Router
has tried every available modes of sending Binding Updates and still has tried every available modes of sending Binding Updates and still
has not received a positive Binding Acknowledgement (status value has not received a positive Binding Acknowledgement (status value
between 0 and 127) for this Home Address from any Home Agent on its between 0 and 127) for this Home Address from any Home Agent on its
home link, then the Mobile Router MUST stop sending Binding Updates home link, then the Mobile Router MUST stop sending Binding Updates
with the Mobile Router flag set for this Home Address and log the with the Mobile Router flag set for this Home Address and log the
information. information.
In all the above cases, the Mobile Router MUST conclude that the Home In all the above cases, the Mobile Router MUST conclude that the Home
Agent did not create a binding cache entry for the Mobile Router's Agent did not create a binding cache entry for the Mobile Router's
Home Address. Home Address.
5.5. Establishment of Bi-directional Tunnel 5.5. Establishment of Bi-directional Tunnel
When a successful Binding Acknowledgement with status set to '2' When a successful Binding Acknowledgement is received, the Mobile
(Mobile Router Binding Update accepted) is received, the Mobile Router sets up its endpoint of the bi-directional tunnel.
Router set up its endpoint of the bi-directional tunnel.
The bi-directional tunnel between Mobile Router and Home Agent allows The bi-directional tunnel between Mobile Router and Home Agent allows
packets to flow in both directions between these entities, while the packets to flow in both directions between these entities, while the
Mobile Router is connected to a Visited Link. The bi-directional Mobile Router is connected to a Visited Link. The bi-directional
tunnel involves two virtual links [3]: one virtual link has the tunnel involves two virtual links [3]: one virtual link has the
address of the tunnel entry point as the Care-of Address of the address of the tunnel entry point as the Care-of Address of the
Mobile Router and the tunnel exit point as the address of the Mobile Router and the tunnel exit point as the address of the
Home Agent; the other virtual link has as tunnel entry point the Home Agent; the other virtual link has as tunnel entry point the
Home Agent address and as tunnel exit point the Care-of Address Home Agent address and as tunnel exit point the Care-of Address
of the Mobile Router. Both addresses are unicast addresses. All of the Mobile Router. Both addresses are unicast addresses. All
IPv6 traffic to and from the Mobile Network is sent through this IPv6 traffic to and from the mobile network is sent through this
bi-directional tunnel. bi-directional tunnel.
A Mobile Router MAY limit the number of mobile routers that attach to A Mobile Router MAY limit the number of mobile routers that attach to
its mobile network (the number of levels in the nested aggregation) its mobile network (the number of levels in the nested aggregation)
by means of setting the Tunnel Encapsulation Limit field of the by means of setting the Tunnel Encapsulation Limit field of the
Tunnel Encapsulation option. Tunnel Encapsulation option.
A Mobile Router uses the Tunnel Hop Limit that is normally assigned A Mobile Router uses the Tunnel Hop Limit that is normally assigned
to routers (not to hosts). See [3]. to routers (not to hosts). Please refer to [3] for more details.
5.6. Neighbour Discovery for Mobile Router 5.6. Neighbor Discovery for Mobile Router
A Mobile Router MAY be configured to send Router Advertisements and When the Mobile Router is at home, it MAY be configured to send
reply to Router Solicitations on the interface attached to the home Router Advertisements and reply to Router Solicitations on the
link. The value of the Router Lifetime field MUST be set to zero to interface attached to the home link. The value of the Router
prevent other nodes from configuring the Mobile Router as the default Lifetime field MUST be set to zero to prevent other nodes from
router. configuring the Mobile Router as the default router.
A Mobile Router SHOULD NOT send unsolicited Router Advertisements A Mobile Router SHOULD NOT send unsolicited Router Advertisements
and SHOULD NOT reply to Router Solicitations on any egress interface and SHOULD NOT reply to Router Solicitations on any egress interface
when that interface is attached to a visited link. However, the when that interface is attached to a visited link. However, the
Mobile Router SHOULD reply with Neighbor Advertisements to Neighbor Mobile Router SHOULD reply with Neighbor Advertisements to Neighbor
Solicitations received on the egress interface, for topologically Solicitations received on the egress interface, for topologically
correct addresses. correct addresses.
A Mobile Router MUST NOT ignore Router Advertisements received on A router typically ignores router advertisements sent by other
the egress interface. The received Router Advertisements MAY be routers on a link. However, a Mobile Router MUST NOT ignore Router
used for address configuration, default router selection or movement Advertisements received on the egress interface. The received Router
detection. Advertisements MAY be used for address configuration, default router
selection or movement detection.
5.7. Multicast Groups for Mobile Router 5.7. Multicast Groups for Mobile Router
When at home, the Mobile Router joins the multicast group All Routers When at home, the Mobile Router joins the multicast group All Routers
Address with scopes '1' interface-local (on the home-advertising Address with scopes '1' interface-local (on the home-advertising
interface) and '2' link-local on any of its egress interfaces. When interface) and '2' link-local on any of its egress interfaces. When
in a visited network, the Mobile Router MUST NOT join the above in a visited network, the Mobile Router MUST NOT join the above
multicast groups on the corresponding interface. multicast groups on the corresponding interface.
5.8. Returning Home
When the Mobile Router realizes it has returned to its home link
through movement detection mechanisms, it MUST de-register with
its Home Agent. The Mobile Router MUST implement and follow the
returning home procedures defined for a mobile node in [1]. In
addition, the Mobile Router MAY start behaving as a router on its
egress interface. In particular,
- The Mobile Router MAY send router advertisements on its egress
interfaces. But the router lifetime SHOULD be set to 0, so that
hosts on the home link do not pick the Mobile Router as the
default router.
- The Mobile Router MAY join the All Routers multicast group on the
home link.
- The Mobile Router MAY send routing protocol messages on its
egress interface if it is configured to run a dynamic routing
protocol.
6. Home Agent Operation 6. Home Agent Operation
In order for a Mobile Router to operate correctly, the Home Agent In order for a Mobile Router to operate correctly, the Home Agent
MUST satisfy all the requirements listed in section 8.4 of [1]. The MUST satisfy all the requirements listed in Section 8.4 of [1]. The
Home Agent MUST implement all the modes described in Section 5.2. Home Agent MUST implement both modes described in Section 5.2 of this
document.
6.1. Data Structures 6.1. Data Structures
6.1.1. Binding Cache 6.1.1. Binding Cache
The Home Agent maintains Binding Cache Entries for each Mobile Router The Home Agent maintains Binding Cache Entries for each Mobile Router
that is currently registered with the Home Agent. The Binding Cache that is currently registered with the Home Agent. The Binding Cache
is a conceptual data structure described in detail in [1]. is a conceptual data structure described in detail in [1].
The Home Agent might need to store the Mobile Network Prefixes The Home Agent might need to store the Mobile Network Prefixes
associated with a Mobile Router in the corresponding Binding Cache associated with a Mobile Router in the corresponding Binding Cache
Entry. This is required if the Binding Update (that created the Entry. This is required if the Binding Update (that created the
Binding Cache Entry) contained explicit prefix information. This Binding Cache Entry) contained explicit prefix information. This
information can be used later to cleanup routes installed in explicit information can be used later to cleanup routes installed in explicit
mode, when the Binding Cache Entry is removed, and to maintain the mode, when the Binding Cache Entry is removed, and to maintain the
routing table, for instance should the routes be manually removed. routing table, for instance should the routes be manually removed.
The Home Agent also stores the status of the Mobile Router Flag 'R' The Home Agent also stores the status of the Mobile Router Flag (R)
in the Binding Cache entry. in the Binding Cache entry.
6.1.2. Prefix Table 6.1.2. Prefix Table
In some deployment scenarios it may be necessary for the Home Agent The Home Agent SHOULD be able to prevent a Mobile Router from
to prevent a misbehaving Mobile Router from claiming mobile network claiming Mobile Network Prefixes that belong to another Mobile
prefixes belonging to another Mobile Router. The Home Agent can Router. The Home Agent can prevent such attacks if it maintains a
prevent such attacks if it maintains a Prefix Table and verifies the Prefix Table and verifies the Prefix Information provided by the
Prefix Information provided by the Mobile Router against the entries Mobile Router against the entries in the Prefix Table. The Prefix
in the Prefix Table. However, this verification is done only if the Table SHOULD be used by the Home Agent when it processes a Binding
Binding Update contained explicit prefix information in the form of Update in explicit mode. It is not required when a dynamic routing
either the Mobile Network Prefix Option or the Mobile Network Prefix protocol is run between the Mobile Router and the Home Agent.
Length Option.
Each entry in the Prefix Table conceptually contains the following Each entry in the Prefix Table conceptually contains the following
fields: fields:
- The Home Address of the Mobile Router. This field is used as the - The Home Address of the Mobile Router. This field is used as the
key for searching the pre-configured prefix table. key for searching the pre-configured prefix table.
- The Mobile Network Prefix of the Mobile Router associated with - The Mobile Network Prefix of the Mobile Router associated with
the Home Address. the Home Address.
6.2. Mobile Network Prefix Registration 6.2. Mobile Network Prefix Registration
The Home Agent processes the Binding Update as described in section The Home Agent processes the Binding Update as described in Section
10.3.1 of the Mobile IPv6 specification [1]. This section describes 10.3.1 of the Mobile IPv6 specification [1]. This section describes
the processing of the Binding Update if the Mobile Router (R) flag is the processing of the Binding Update if the Mobile Router (R) flag is
set. The Home Agent performs the following check in addition. set. The Home Agent performs the following check in addition.
- The Home Registration (H) flag MUST be set. If not, the - The Home Registration (H) flag MUST be set. If not, the
Home Agent MUST reject the Binding Update and send a Binding Home Agent MUST reject the Binding Update and send a Binding
Acknowledgement with status set to 140. Note: The basic support Acknowledgement with status set to 140. Note: The basic support
does not allow sending Binding Update for a Mobile Network Prefix does not allow sending Binding Update for a Mobile Network Prefix
to correspondent nodes (for route optimization). to correspondent nodes (for route optimization).
- If the Mobile Network Prefix Length option is present in - Mobile IPv6 specification [1] requires that the Home Address in
the Binding Update, then there MUST be only one instance of the Binding Update should be configured from a prefix advertised
this option in the Binding Update. Also the Mobile Network on the home link. Otherwise the Binding Update is rejected
Prefix Option MUST NOT be present in the same Binding Update. with status value 132 [1]. This specification relaxes this
Otherwise, the Home Agent MUST discard the Binding Update and requirement so that the Home Agent rejects the Binding Update
send an ICMP Parameter Problem, Code 0, message to the Mobile only if Home Address does not belong to the prefix that the Home
Router. Agent is configured to serve.
If the Home Agent does not reject the Binding Update as described If the Home Agent does not reject the Binding Update as described
above, then it retrieves the Mobile Network Prefix information as above, then it retrieves the Mobile Network Prefix information as
described below. described below.
- If a Mobile Network Prefix Length Option is present in the
Binding Update, the Home Address in the Home Address destination
option MUST be an Home Address. In that case, the Mobile Network
Prefix is obtained from that Home Address and the prefix length
in the Mobile Network Prefix Length Option.
If the Home Agent verfies the prefix information with the Prefix
Table and the check fails, the Home Agent MUST discard the
Binding Update and send a Binding Acknowldegement with status set
to 142 (Not Authorized for Prefix).
- If a Mobile Network Prefix Option is present in the Binding - If a Mobile Network Prefix Option is present in the Binding
Update, the prefix information for the mobile network prefix is Update, the prefix information for the Mobile Network Prefix is
retrieved from the Mobile Network Prefix field and the Prefix retrieved from the Mobile Network Prefix field and the Prefix
Length field of the option. If the Binding Update contains more Length field of the option. If the Binding Update contains more
than one option, the Home Agent MUST set up forwarding for all of than one option, the Home Agent MUST set up forwarding for all of
the Mobile Network Prefixes. If the Home Agent fails to setup the Mobile Network Prefixes. If the Home Agent fails to setup
forwarding to all the prefixes listed in the Binding Update, then forwarding to all the prefixes listed in the Binding Update, then
it MUST NOT forward traffic to any of the prefixes, reject the it MUST NOT forward traffic to any of the prefixes, reject the
Binding Update and send a Binding Acknowledgement with status set Binding Update and send a Binding Acknowledgement with status set
to 141 (Invalid Prefix). to 141 (Invalid Prefix).
If the Home Agent verifies the prefix information with the Prefix If the Home Agent verifies the prefix information with the Prefix
Table and the check fails, the Home Agent MUST discard the Table and the check fails, the Home Agent MUST discard the
Binding Update and send a Binding Acknowldegement with status set Binding Update and send a Binding Acknowldegement with status set
to 142 (Not Authorized for Prefix). to 142 (Not Authorized for Prefix).
- If there are no options in the Binding Update, the Home Agent - If there are is no option in the Binding Update carying
uses manual pre-configured information to determine the prefixes prefix information, the Home Agent uses manual pre-configured
assigned to the Mobile Router and for setting up forwarding for information to determine the prefixes assigned to the Mobile
the Mobile Network. If there is no information that the Home Router and for setting up forwarding for the mobile network. If
Agent can use, it MUST reject the Binding Update and send a there is no information that the Home Agent can use, it MUST
Binding Acknowledgement with status set to 143 (Forwarding Setup reject the Binding Update and send a Binding Acknowledgement with
failed). status set to 143 (Forwarding Setup failed).
If the Lifetime specified in the Binding Update is zero or the If the Lifetime specified in the Binding Update is zero or the
specified Care-of address matches the Home Address in the Binding specified Care-of address matches the Home Address in the Binding
Update, then this is a request to delete the cached binding for Update, then this is a request to delete the cached binding for
the home address and specified Mobile Network Prefixes. The the home address and specified Mobile Network Prefixes. The
Binding Update is processed according to the procedure described in Binding Update is processed according to the procedure described in
section 6.7. Section 6.7.
If all checks are passed, the Home Agent creates a binding cache If all checks are passed, the Home Agent creates a binding cache
entry for Mobile Router's Home Address, or updates the binding cache entry for Mobile Router's Home Address, or updates the binding cache
entry if it already exists. Otherwise, the Home Agent MUST NOT entry if it already exists. Otherwise, the Home Agent MUST NOT
register the binding of the Mobile Router's Home Address. register the binding of the Mobile Router's Home Address.
The Home Agent defends the Mobile Router's Home Address through Proxy The Home Agent defends the Mobile Router's Home Address through Proxy
Neighbor Discovery by multicasting onto the home like a Neighbor Neighbor Discovery by multicasting onto the home link a Neighbor
Advertisement message on behalf of the mobile router. All fields in Advertisement message on behalf of the mobile router. All fields in
each such Neighbor Advertisement message SHOULD be set in the same the Proxy Neighbor Advertisement message should be set in the same
way they would be set by the mobile router itself if sending this way they would be set by the Mobile Router itself if sending this
Neighbor Advertisement while at home, as described in [7], with the Neighbor Advertisement while at home, as described in [7], with the
exception that the Router (R) bit in the Advertisement MUST be set if exception that the Router (R) bit in the Advertisement MUST be set if
the Mobile Router (R) flag has been set in the Binding Update. the Mobile Router (R) flag has been set in the Binding Update.
The Home Agent also creates a bi-directional tunnel to the mobile The Home Agent also creates a bi-directional tunnel to the mobile
router for the requested Mobile Network Prefix, or update an existing router for the requested Mobile Network Prefix, or update an existing
bi-directional tunnel as described in section 6.4. bi-directional tunnel as described in Section 6.4.
6.3. Advertising Mobile Network Reachability 6.3. Advertising Mobile Network Reachability
In order to be able to receive packets meant for the mobile network, In order to be able to receive packets meant for the mobile network,
the Home Agent advertises reachability to the mobile network. If the the Home Agent advertises reachability to the mobile network. If the
Home Link is configured with a prefix that is an aggregation and if Home Link is configured with a prefix that is an aggregation and if
the Mobile Network Prefix is aggregated under that prefix, then the the Mobile Network Prefix is aggregated under that prefix, then the
routing updates advertising reachability to the mobile network are routing updates advertising reachability to the mobile network are
sent only on the Home Link. If the Home Agent is the only default sent only on the Home Link. If the Home Agent is the only default
router on the Home Link, routes to the Mobile Network Prefix get router on the Home Link, routes to the Mobile Network Prefix get
aggregated naturally under the Home Agent and the Home Agent does not aggregated naturally under the Home Agent and the Home Agent does not
have to do anything special. have to do anything special.
If the Home Agent receives routing updates through a dynamic routing If the Home Agent receives routing updates through a dynamic routing
protocol from the Mobile Router, those routes are propagated by protocol from the Mobile Router, those routes are propagated by
the routing protocol running on the Home Agent on the relevant the routing protocol running on the Home Agent on the relevant
interfaces. interfaces.
6.4. Establishment of Bi-directional Tunnel 6.4. Establishment of Bi-directional Tunnel
The establishment and operation of the bi-directional tunnel is The implementation of the bi-directional tunnels and the mechanism
implementation specific. However, all implementations MUST be of attaching them to the IP stack are outside the scope of this
capable of the following operations. specification. However, all implementations MUST be capable of the
following operations.
- The Home Agent can tunnel packets meant for the mobile network - The Home Agent can tunnel packets meant for the mobile network
prefix to the Mobile Router's current location, the Care-of prefix to the Mobile Router's current location, the Care-of
Address of the Mobile Router. Address of the Mobile Router.
- The Home Agent can accept packets tunneled by the Mobile Router - The Home Agent can accept packets tunneled by the Mobile Router
with source address of the outer IPv6 header set to the Care-of with source address of the outer IPv6 header set to the Care-of
Address of the Mobile Router. Address of the Mobile Router.
6.5. Forwarding Packets 6.5. Forwarding Packets
When the Home Agent receives a data packet destined for the mobile When the Home Agent receives a data packet destined for the mobile
network, it fowards the packet to the Mobile Router through the network, it MUST forward the packet to the Mobile Router through the
bi-directional tunnel. The Home Agent either uses only the routing bi-directional tunnel. The Home Agent either uses only the routing
table, only the Binding Cache or a combination of routing table table, only the Binding Cache or a combination of routing table
and Binding Cache to route packets to the mobile network. This is and Binding Cache to route packets to the mobile network. This is
implementation specific. Two examples are shown below. implementation specific. Two examples are shown below.
1. The Home Agent maintains a route to the Mobile Network Prefix 1. The Home Agent maintains a route to the Mobile Network Prefix
with the next hop set to the Mobile Router's Home Address. When with the next hop set to the Mobile Router's Home Address. When
the Home Agent tries to forward the packet to the next hop, it the Home Agent tries to forward the packet to the next hop, it
finds a binding cache entry for the home address. Then the Home finds a binding cache entry for the home address. Then the Home
Agent extracts the Mobile Router's Care-of address and tunnels Agent extracts the Mobile Router's Care-of address and tunnels
skipping to change at page 22, line 9 skipping to change at page 21, line 45
interface. When the packets are forwarded through the tunnel interface. When the packets are forwarded through the tunnel
interface, they get encapsulated automatically with the source interface, they get encapsulated automatically with the source
address and destination address in the outer IPv6 header set to address and destination address in the outer IPv6 header set to
the Home Agent's address and the Mobile Router's Care-of address, the Home Agent's address and the Mobile Router's Care-of address,
respectively. respectively.
6.6. Sending Binding Acknowledgements 6.6. Sending Binding Acknowledgements
A Home Agent serving a Mobile Router sends Binding Acknowledgements A Home Agent serving a Mobile Router sends Binding Acknowledgements
according to the same rules it uses for sending Binding according to the same rules it uses for sending Binding
Acknowledgements to Mobile Hosts, with the following enhancements. Acknowledgements to Mobile Hosts [1], with the following
enhancements.
The Home Agent sets the status code in the Binding Acknowledgement The Home Agent sets the status code in the Binding Acknowledgement
to '2' (Mobile Router Binding Update accepted) in order to indicate to '0' (Binding Update accepted) in order to indicate to the Mobile
to the Mobile Router that it accepted the Binding Update, set up the Router that it successfully processed the Binding Update. It also
tunnel endpoint and the necessary forwarding information. sets the Mobile Router flag (R) to indicate to the Mobile Router that
it has setup forwarding for the mobile network.
If the Home Agent is configured not to support mobile routers, it If the Home Agent is configured not to support mobile routers, it
sets the status code in the Binding Acknowledgement to '140' (Mobile sets the status code in the Binding Acknowledgement to '140' (Mobile
Router Operation not permitted). Router Operation not permitted).
If one or more prefixes received in the Binding Update are invalid If one or more prefixes received in the Binding Update are invalid
and the Home Agent cannot setup forwarding for the prefixes, the Home and the Home Agent cannot setup forwarding for the prefixes, the Home
Agent sets the status code in the Binding Acknowledgement to '141' Agent sets the status code in the Binding Acknowledgement to '141'
(Invalid Prefix) in order to indicate this to the Mobile Router. (Invalid Prefix) in order to indicate this to the Mobile Router.
If the Mobile Router is not authorized to use this Home Address to If the Mobile Router is not authorized to use this Home Address to
forward packets for one or more prefixes that are present in the forward packets for one or more prefixes that are present in the
Binding Update, the Home Agent sets the status code in the Binding Binding Update, the Home Agent sets the status code in the Binding
Acknowledgement to '142' (Not Authorized for Prefix) in order to Acknowledgement to '142' (Not Authorized for Prefix) in order to
indicate this. indicate this.
The Home Agent sets the status code to 143 (Forwarding Setup The Home Agent sets the status code to 143 (Forwarding Setup
failed) if it is unable to determine the information needed to setup failed) if it is unable to determine the information needed to setup
forwarding for the Mobile Network. This is used in the Implicit mode forwarding for the mobile network. This is used in the Implicit mode
where the Mobile Router does not include any prefix information in where the Mobile Router does not include any prefix information in
the Binding Update. the Binding Update.
6.7. Mobile Network Prefix De-Registration 6.7. Mobile Network Prefix De-Registration
The Mobile Router de-registers with the Home Agent by sending a The Mobile Router de-registers with the Home Agent by sending a
Binding Update with the lifetime set to zero. When the Home Agent Binding Update with the lifetime set to zero. When the Home Agent
successfully processes the de-registration BU, it deletes the Binding successfully processes the de-registration BU, it deletes the Binding
Cache Entry for the Mobile Router's Home Address and stops proxying Cache Entry for the Mobile Router's Home Address and stops proxying
the Home Address. This is described in detail in the Mobile IPv6 the Home Address. This is described in detail in the Mobile IPv6
specification [1]. specification [1].
In addition, the Home Agent also removes the bi-directional tunnel In addition, the Home Agent also removes the bi-directional tunnel
and stops forwarding packets to the mobile network. The HA should and stops forwarding packets to the mobile network. The Home Agent
keep all necessary information to clean up whichever routes it should keep all necessary information to clean up whichever routes it
installed, whether they come from implicit or explicit source. installed, whether they come from implicit or explicit source.
7. Support for Dynamic Routing Protocols 7. Modifications to Dynamic Home Agent Discovery
In the solution described so far, forwarding to the Mobile Network This document extends the Dynamic Home Agent Discovery mechanism
defined in [1], so that Mobile Routers attempt registration only with
Home Agents that support Mobile Routers.
7.1. Modified Dynamic Home Agent Discovery Request
A new flag (R) (Support for Mobile Routers) is introduced in the
Dynamic Home Agent Discovery Reguest message defined in [1]. The
Mobile Router sets this flag to indicate that it wants to discover
Home Agents that support Mobile Routers.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |R| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Mobile Router Support Flag (R)
A 1 bit flag which when set indicates that the Mobile Router
wants to discover Home Agents that support Mobile Routers.
For a description of the other fields in the message, see [1].
7.2. Modified Dynamic Home Agent Discovery Reply
A new flag (R) (Support for Mobile Routers) is introduced in the
Dynamic Home Agent Discovery Reply message defined in [1]. If a Home
Agent receives a Dynamic Home Agent Discovery request message with
the Mobile Router Support flag set, it MUST reply with a list of Home
Agents that support Mobile Routers. The Mobile Router Support flag
MUST be set if there is atleast one Home Agent that supports Mobile
Routers. If none of the Home Agents support Mobile Routers, the Home
Agent MAY reply with a list of Home Agents that support just Mobile
IPv6 Mobile Nodes. In this case, the Mobile Router Support flag MUST
be set to 0.
The modified message 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 | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |R| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
. .
. Home Agent Addresses .
. .
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Mobile Router Support Flag (R)
A 1 bit flag which when set indicates that the Home Agents
listed in this message support Mobile Routers.
For a description of the other fields in the message, see [1].
7.3. Modified Home Agent Information Option
A new flag (R) (Support for Mobile Routers) is introduced in the Home
Agent Information Option defined in [1]. If a Home Agent supports
Mobile Routers, it SHOULD set the flag.
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 | Length |R| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Agent Preference | Home Agent Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Mobile Router Support Flag (R)
A 1 bit flag which when set indicates that the Home Agent
supports Mobile Routers.
For a description of the other fields in the message, see [1].
8. Support for Dynamic Routing Protocols
In the solution described so far, forwarding to the mobile network
at the Home Agent is set up when the Home Agent receives a Binding at the Home Agent is set up when the Home Agent receives a Binding
Update from the Mobile Router. An alternative to this is for the Update from the Mobile Router. An alternative to this is for the
Home Agent and the Mobile Router to run a intra-domain routing Home Agent and the Mobile Router to run an intra-domain routing
protocol like RIPng [10] and OSPF [11] through the bi-directional protocol like RIPng [11] and OSPF [12] through the bi-directional
tunnel. The Mobile Router can continue running the same routing tunnel. The Mobile Router can continue running the same routing
protocol that it was running when it was attached to the home link. protocol that it was running when it was attached to the home link.
This feature is very useful when the Mobile Network is large with This feature is very useful when the mobile network is large with
multiple subnets containing different IPv6 prefixes. Routing changes multiple subnets containing different IPv6 prefixes. Routing changes
in the Mobile Network are propagated to the Home Agent quickly. in the mobile network are propagated to the Home Agent quickly.
Routing changes in the home link are also propogated to the Mobile Routing changes in the home link are also propogated to the Mobile
Router very quickly. Router very quickly.
When the Mobile Router is attached to the home link, it runs a When the Mobile Router is attached to the home link, it runs a
routing protocol by sending routing updates through its egress routing protocol by sending routing updates through its egress
interface. When the mobile router moves and attaches to a visited interface. When the mobile router moves and attaches to a visited
network, it MUST stop sending routing updates on the interface with network, it MUST stop sending routing updates on the interface with
which it attaches to the visited link. This is very important so which it attaches to the visited link. This is very important so
that IPv6 prefixes specific to the Mobile Network do not leak into that IPv6 prefixes specific to the mobile network do not leak into
the visited network. The Mobile Router then starts sending routing the visited network. The Mobile Router then starts sending routing
protocol messages through the bi-directional tunnel towards the Home protocol messages through the bi-directional tunnel towards the Home
Agent. Most routing protocols use link local addresses as source Agent. Most routing protocols use link local addresses as source
addresses for the routing information messages. The Mobile Router is addresses for the routing information messages. The Mobile Router is
allowed to use link local addresses for the inner IPv6 header of an allowed to use link local addresses for the inner IPv6 header of an
encapsulated packet. But these messages after decapsulation MUST NOT encapsulated packet. But these messages after decapsulation MUST NOT
be forwarded to another link by either the Mobile Router or the Home be forwarded to another link by either the Mobile Router or the Home
Agent. Agent.
When the Home Agent receives the encapsulated routing protocol When the Home Agent receives the encapsulated routing protocol
skipping to change at page 23, line 51 skipping to change at page 25, line 51
Similary, the Home Agent also sends routing updates through the Similary, the Home Agent also sends routing updates through the
bi-directional tunnel to the Mobile Router. The Mobile Router bi-directional tunnel to the Mobile Router. The Mobile Router
processes these routing protocol messages and updates its routing processes these routing protocol messages and updates its routing
table. For all routes advertised by the Home Agent, the Mobile table. For all routes advertised by the Home Agent, the Mobile
Router sets the outgoing interface to the bi-directional tunnel to Router sets the outgoing interface to the bi-directional tunnel to
the Home Agent. the Home Agent.
When the Mobile Router and the Home Agent exchange routes through When the Mobile Router and the Home Agent exchange routes through
a dynamic routing protocol, the Mobile Router should be careful in a dynamic routing protocol, the Mobile Router should be careful in
including the same mobile network prefixes in the Binding Update to including the same Mobile Network Prefixes in the Binding Update to
the HA and in the routing protocol updates. The HA depending on its the Home Agent and in the routing protocol updates. The Home Agent
configuration might not add routes based on the prefix information in depending on its configuration might not add routes based on the
the Binding Updates at all, and might use only the routing protocol prefix information in the Binding Updates at all, and might use only
updates. Moreover, including the same prefix information in both the the routing protocol updates. Moreover, including the same prefix
Binding Update and the routing protocol update is redundant. information in both the Binding Update and the routing protocol
update is redundant.
The tunneled routing messages MUST be authenticated and encrypted by Since the routing protocol messages from the Home Agent to the Mobile
using IPsec ESP [4] in tunnel mode. Router could potentially contain information about the internal
routing structure of the home network, these messages require
authentications and confidentiality protection. Confidentialy
protection using IPsec ESP [4] MUST be supported and SHOULD be
used. For protecting routing protocol messages using ESP, the
bi-directional tunnel between the Mobile Router and the Home
Agent should be treated as the outgoing interface, with link local
addresses as source and destination addresses for the messages.
IPsec ESP with a non-null encryption algorithm should be used
in transport mode for protecting the routing protocol messages.
Examples of SPD entries for protecting OSPFv3 messages are described
in [13].
8. Security Considerations 9. Security Considerations
All signaling messages between the Mobile Router and the Home Agent All signaling messages between the Mobile Router and the Home Agent
MUST be authenticated by IPsec [5]. The use of IPsec to protect MUST be authenticated by IPsec [5]. The use of IPsec to protect
Mobile IPv6 signaling messages is described in detail in the HA-MN Mobile IPv6 signaling messages is described in detail in the HA-MN
IPsec specification [2]. The signaling messages described in this IPsec specification [2]. The signaling messages described in this
document just extend Mobile IPv6 messages and do not require any document just extend Mobile IPv6 messages and do not require any
changes to what is described in the HA-MN IPsec specification. changes to what is described in the HA-MN IPsec specification.
The Mobile Router has to perform ingress filtering on packets
received from the mobile network to ensure that nodes in the Mobile
Network do not use the bi-directional tunnel to launch IP spoofing
attacks. In particular the Mobile Router SHOULD check that the IP
source address in the packets received from the nodes in the Mobile
Network belongs to the Mobile Network Prefix and is not the same as
one of the addresses used by the Mobile Router. In case the Mobile
Router receives a IP-in-IP tunneled packet from a node in the Mobile
Network and the Mobile Router has to forward the decapsulated packet,
it SHOULD perform the above mentioned checks on the source address of
the inner packet.
The Home Agent has to verify that packets received through the The Home Agent has to verify that packets received through the
bi-directional tunnel belong to the Mobile Network. This check is bi-directional tunnel belong to the mobile network. This check is
necessary in order to prevent nodes from using the Home Agent to necessary in order to prevent nodes from using the Home Agent to
launch attacks that would have otherwise been prevented by ingress launch attacks that would have otherwise been prevented by ingress
filtering. The source address of the outer IPv6 header MUST be set filtering. The source address of the outer IPv6 header MUST be set
the Mobile Router's current Care-of address. The source address of to the Mobile Router's current Care-of address. The source address
the inner IPv6 header MUST belong to the Mobile Network Prefix owned of the inner IPv6 header MUST be a topologically correct address with
by the Mobile Router. respect to the IPv6 prefixes used in the mobile network.
When the Mobile Router is running a dynamic routing protocol as When the Mobile Router is running a dynamic routing protocol as
described in section 7, it injects routing update messages into the described in Section 8, it injects routing update messages into the
Home Link. The Home Agent MUST verify that the Mobile Router is Home Link. The Home Agent MUST verify that the Mobile Router is
allowed to send routing updates before processing the messages and allowed to send routing updates before processing the messages and
propagating the routing information. propagating the routing information.
Please refer to the Mobile IPv6 specification [1] for security Please refer to the Mobile IPv6 specification [1] for security
considerations when the Mobile Router operates as a Mobile Host. considerations when the Mobile Router operates as a Mobile Host.
9. IANA Considerations 10. IANA Considerations
This document defines two new Mobility Header Options. This document defines a new Mobility Header Option, the Mobile
Network Prefix Option. This option is described in Section 4.3. The
type value for this option needs to be assigned from the same space
used by the mobility options defined in [1].
- Mobile Network Prefix Option. This document also defines the following new Binding Acknowledgement
status values. These status values are defined in Section 4.2
and need to be assigned from the same space used for Binding
Acknowledgement status values in [1].
- Mobile Network Prefix Length Option. - Mobile Router Operation not permitted
These options are described in section 4.3 and section 4.4. The type - Invalid Prefix
values for these options need to assigned from the same space used by
the mobility options defined in [1]
10. Contributors - Not Authorized for Prefix
- Forwarding Setup failed
11. Contributors
We would like to acknowledge Ludovic Bellier, Claude Castelluccia, We would like to acknowledge Ludovic Bellier, Claude Castelluccia,
Thierry Ernst, Miguel Catalina-Gallego, Christophe Janneteau, T.J. Thierry Ernst, Miguel Catalina-Gallego, Christophe Janneteau, T.J.
Kniveton, Hong-Yon Lach, Jari T. Malinen, Koshiro Mitsuya, Alexis Kniveton, Hong-Yon Lach, Jari T. Malinen, Koshiro Mitsuya, Alexis
Olivereau, Charles E. Perkins and Keisuke Uehara, for their work on Olivereau, Charles E. Perkins and Keisuke Uehara, for their work on
earlier proposals for Network Mobility. This document inherits a lot earlier proposals for Network Mobility. This document inherits a lot
of ideas from these proposals. of ideas from these proposals.
11. Acknowledgements 12. Acknowledgements
We thank all members of the NEMO Working Group, and of the preceding We thank all members of the NEMO Working Group, and of the preceding
MONET BoF for fruitful discussions on the mailing list and at IETF MONET BoF for fruitful discussions on the mailing list and at IETF
meetings. meetings.
Kent Leung, Marco Molteni and Patrick Wetterwald for their work on Kent Leung, Marco Molteni and Patrick Wetterwald for their work on
Network Mobility for IPv4 and IPv6. Network Mobility for IPv4 and IPv6.
Tim Leinmueller for many insightful remarks and implementation Tim Leinmueller for many insightful remarks and for Section 7.
aspects.
Normative References Jari Arkko, James Kempf and Chan-Wah Ng for their thorough review and
comments.
References
[1] D. Johnson, C. Perkins and J. Arkko. Mobility Support in IPv6. [1] D. Johnson, C. Perkins and J. Arkko. Mobility Support in IPv6.
Internet Draft, IETF. draft-ietf-mobileip-ipv6-24.txt (work in Internet Draft, IETF. draft-ietf-mobileip-ipv6-24.txt (work in
progress). June 2003. progress). June 2003.
[2] J. Arkko, V. Devarapalli and F. Dupont. Using IPsec to Protect [2] J. Arkko, V. Devarapalli and F. Dupont. Using IPsec to Protect
Mobile IPv6 Signaling between Mobile Nodes and Home Agents. Mobile IPv6 Signaling between Mobile Nodes and Home Agents.
Internet Draft, IETF. draft-ietf-mobileip-mipv6-ha-ipsec-06.txt Internet Draft, IETF. draft-ietf-mobileip-mipv6-ha-ipsec-06.txt
(work in progress). June 2003. (work in progress). June 2003.
skipping to change at page 27, line 31 skipping to change at page 29, line 31
[5] S. Kent and R. Atkinson. Security Architecture for the Internet [5] S. Kent and R. Atkinson. Security Architecture for the Internet
Protocol. RFC 2401, IETF. November 1998. Protocol. RFC 2401, IETF. November 1998.
[6] S. Deering and R. Hinden. Internet Protocol, Version 6 (IPv6) [6] S. Deering and R. Hinden. Internet Protocol, Version 6 (IPv6)
Specification. RFC 2460, IETF. December 1998. Specification. RFC 2460, IETF. December 1998.
[7] T. Narten, E. Nordmark and W. Simpson. Neighbour Discovery for [7] T. Narten, E. Nordmark and W. Simpson. Neighbour Discovery for
IP Version 6 (IPv6). RFC 2461, IETF. December 1998. IP Version 6 (IPv6). RFC 2461, IETF. December 1998.
Informative References References
[8] T. Ernst and H.-Y. Lach. Network Mobility Support Terminology. [8] J. Manner and M. Kojo. Mobility Related Terminology. Internet
Draft, IETF. draft-ietf-seamoby-mobility-terminology-05.txt
(work in progress). November 2003.
[9] T. Ernst and H.-Y. Lach. Network Mobility Support Terminology.
Internet Draft, IETF. draft-ietf-nemo-terminology-00.txt (work Internet Draft, IETF. draft-ietf-nemo-terminology-00.txt (work
in progress). May 2003. in progress). May 2003.
[9] T. Ernst. Network Mobility Support Goals and Requirements. [10] T. Ernst. Network Mobility Support Goals and Requirements.
Internet Draft, IETF. draft-ietf-nemo-requirements-01.txt (work Internet Draft, IETF. draft-ietf-nemo-requirements-01.txt (work
in progress). May 2003. in progress). May 2003.
[10] G. Malkin and R. Minnear. RIPng for IPv6. RFC 2080, IETF. [11] G. Malkin and R. Minnear. RIPng for IPv6. RFC 2080, IETF.
January 1997. January 1997.
[11] R. Coltun, D. Ferguson and J. Moy. OSPF for IPv6. RFC 2470, [12] R. Coltun, D. Ferguson and J. Moy. OSPF for IPv6. RFC 2470,
IETF. December 1999. IETF. December 1999.
A. Examples of Operation [13] M. Gupta and N. Melam. Authentication/Confidentiality for
OSPFv3. Internet Draft, IETF. draft-ietf-ospf-ospfv3-auth-04.txt
(work in progress). December 2003.
[14] T. Ernst. Network Mobility Support in IPv6. PhD Thesis,
University Joseph Fourier, Grenoble, France. October 2001.
[15] T. Ernst, K, Mitsuya and K. Uehara. Network Mobility from the
InternetCAR perspective. Journal of Interconnection Networks
(JOIN), Vol. 4, No. 3. September 2003.
A. Examples of NEMO Basic Support Operation
This section tries to illustrate the NEMO protocol using a Mobile This section tries to illustrate the NEMO protocol using a Mobile
Router and a Mobile Node belonging to different administrative Router and a Mobile Node belonging to different administrative
domains. The Mobile Router's mobile network consists of a Local domains. The Mobile Router's mobile network consists of a Local
Fixed Node (LFN) and a Local Fixed Router (LFR) [8]. The LFR has Fixed Node (LFN) and a Local Fixed Router (LFR) [9]. The LFR has
an access link to which other Mobile Nodes or Mobile Routers could an access link to which other Mobile Nodes or Mobile Routers could
attach to. attach to.
Figure 1 depicts the scenario where both the Mobile Router and the Figure 1 depicts the scenario where both the Mobile Router and the
Mobile Node are at home. Mobile Node are at home.
+----+ +-------+ +----+ +-------+
| MN | | HA_MN | | MN | | HA_MN |
+--+-+ 1:: +---+---+ +--+-+ 1:: +---+---+
2+-------------+3 2+-------------+3
skipping to change at page 31, line 7 skipping to change at page 34, line 7
|2 |2
+--+-+ +--+-+
| MN | | MN |
+----+ +----+
Figure 3: Mobile Node attached to Mobile Figure 3: Mobile Node attached to Mobile
Router on a Visited Link Router on a Visited Link
B. Changes from Previous Version B. Changes from Previous Version
The following changes have been made to this document from version 00 The following changes have been made to this document from version 01
- Clarified that Router flag must be set in the Proxy Neighbor - Dynamic Home Agent Discovery was modified to return only Home
Advertisement sent for a Mobile Router by the Home Aagent. Agents that support Mobile Routers. A new section was added to
(Issue 1). the specification. (Issue 16).
- Clarified that if the Router flag in the Binding Update is set, - A new flag (R) was introduced in the Binding Acknowledgement for
then the HA should assume that the Mobile Router wants to be the Home Agent to indicate to the Mobile Router that it processed
treated as a mobile node. (Issue 3). the Mobile Router flag (R) in the corresponding Binding Update.
(Issue 16).
- Added text to make it clear that the Home Agent must perform - Relaxed a Mobile IPv6 requirement which said the Home Agent MUST
ingress filtering on all packets reverse tunneled by the Mobile drop a Binding Update if the home address is not configured from
Router. (Issue 3). the home prefix. NEMO Home Agent drops the Binding Update only
if the Home Address does not belong to the prefix that the Home
Agent is currently configured to serve. (Issue 19)
- Extended Home Network concept has been removed from this - Explicit Prefix Length mode is removed. (Issue 20).
document. (Issue 5).
- Added text to clarify differences between Implicit mode and - Text related to Mobile Router performing ingress filtering was
running a dynamic routing protocol. (Issue 6). added to the Security Considerations section to prevent some
threats due to tunneling. (Issue 23).
- Clarified that Prefix Table is used only in explicit mode. In - Added a new section on Mobile Router returning home. (Issue 25).
Implicit mode the Prefix Table is not used. (Issue 7 and 12).
- Added text to specify the Home Agent must support all modes. The - Clarified that the Prefix Table is not required when a dynamic
Mobile Router needs to support only one mode. (Issue 11). routing protocol is being run between the Mobile Router and the
Home Agent. (Issue 26).
- Added text to support interoperability between a Mobile Router - Clarified the use of Prefix Table. (Issue 25).
and a legacy MIPv6 Home Agent. (Issue 15).
- Clarified Mobile Router sending router advertisements on its
egress interface when at home. (Issue 21 and 26).
- Clarified implementation requirements with respect to the Mobile
IPv6 specification. (Issue 27).
- Modified/added network mobility terms so that the NEMO
terminology document becomes an informative reference. (Issue
28).
- Provided more information for creating SPD entries for protecting
routing protocol messages. (Issue 29).
Authors Addresses Authors Addresses
Vijay Devarapalli Vijay Devarapalli
Nokia Research Center Nokia Research Center
313 Fairchild Drive 313 Fairchild Drive
Mountain View, CA 94043 Mountain View, CA 94043
USA USA
Email: vijay.devarapalli@nokia.com Email: vijay.devarapalli@nokia.com
skipping to change at page 33, line 4 skipping to change at page 36, line 4
France France
Email: Alexandru.Petrescu@motorola.com Email: Alexandru.Petrescu@motorola.com
Pascal Thubert Pascal Thubert
Cisco Systems Technology Center Cisco Systems Technology Center
Village d'Entreprises Green Side Village d'Entreprises Green Side
400, Avenue Roumanille 400, Avenue Roumanille
Biot - Sophia Antipolis 06410 Biot - Sophia Antipolis 06410
France France
Email: pthubert@cisco.com Email: pthubert@cisco.com
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Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
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