< 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
	A. Examples of Operation 28		11. Contributors 28
	B. Changes from Previous Version 31		12. Acknowledgements 28
			A. Examples of NEMO Basic Support Operation 31
			B. Changes from Previous Version 34
	Addresses 32
	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 24 ¶		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 5 ¶		skipping to change at page 36, line 5 ¶
	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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