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NETLMM WG S. Gundavelli (Editor) Internet-Draft K. Leung Intended status: Standards Track Cisco Expires:June 27,August 6, 2008 V. Devarapalli Azaire Networks K. Chowdhury Starent Networks B. Patil Nokia Siemens NetworksDecember 25, 2007February 03, 2008 Proxy Mobile IPv6draft-ietf-netlmm-proxymip6-08.txtdraft-ietf-netlmm-proxymip6-09.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire onJune 27,August 6, 2008. Copyright Notice Copyright (C) The IETF Trust(2007).(2008). Abstract Network-based mobility management enables IP mobility for a host without requiring its participation in any mobility relatedGundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 1] Internet-Draft Proxy Mobile IPv6December 2007February 2008 signaling. The Network is responsible for managing IP mobility on behalf of the host. The mobility entities in the network are responsible for tracking the movements of the host and initiating the required mobility signaling on its behalf. This specification describes a network-based mobility management protocol and is referred to as Proxy Mobile IPv6. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions & Terminology . . . . . . . . . . . . . . . . . . 4 2.1. Conventions used in this document . . . . . . . . . . . . 5 2.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 3. Proxy Mobile IPv6 Protocol Overview . . . . . . . . . . . . . 8 4. Proxy Mobile IPv6 Protocol Security . . . . . . . . . . . . . 14 4.1. Peer Authorization Database Entries . . . . . . . . . . . 15 4.2. Security Policy Database Entries . . . . . . . . . . . . . 15 5. Local Mobility Anchor Operation . . . . . . . . . . . . . . . 16 5.1. Extensions to Binding Cache Entry Data Structure . . . . . 16 5.2. Supported Home Network Prefix Models . . . . . . . . . . . 18 5.3. Signaling Considerations . . . . . . . . . . . . . . . . . 18 5.3.1. Processing Binding Registrations . . . . . . . . . . . 18 5.3.2. Initial Binding Registration (New Mobility Session) . 20 5.3.3. Binding Lifetime Extension (No handoff) . . . . . . . 21 5.3.4. Binding Lifetime Extension (After handoff) . . . . . . 22 5.3.5. Binding De-Registration . . . . . . . . . . . . . . . 22 5.3.6. Constructing the Proxy Binding Acknowledgement Message . . . . . . . . . . . . . . . . . . . . . . . 23 5.4. Multihoming Support . . . . . . . . . . . . . . . . . . .2425 5.4.1. Binding Cache entry lookup considerations . . . . . . 26 5.5. Timestamp Option for Message Ordering . . . . . . . . . .2831 5.6. Routing Considerations . . . . . . . . . . . . . . . . . .3033 5.6.1. Bi-Directional Tunnel Management . . . . . . . . . . .3033 5.6.2. Forwarding Considerations . . . . . . . . . . . . . .3134 5.7. Local Mobility Anchor Address Discovery . . . . . . . . .3235 5.8. Mobile Prefix Discovery Considerations . . . . . . . . . .3236 5.9. Route Optimizations Considerations . . . . . . . . . . . .3336 6. Mobile Access Gateway Operation . . . . . . . . . . . . . . .3336 6.1. Extensions to Binding Update List Entry Data Structure . .3437 6.2. Mobile Node's Policy Profile . . . . . . . . . . . . . . .3538 6.3. Supported Access Link Types . . . . . . . . . . . . . . .3538 6.4. Supported Address ConfigurationModelsModes . . . . . . . . . .3639 6.5. Access Authentication & Mobile Node Identification . . . .3639 6.6. Acquiring Mobile Node's Identifier . . . . . . . . . . . .3639 6.7. Home Network Emulation . . . . . . . . . . . . . . . . . .3740 6.8. Link-Local and Global Address Uniqueness . . . . . . . . .3841 6.9. Signaling Considerations . . . . . . . . . . . . . . . . .3942 Gundavelli (Editor), et al. Expires August 6, 2008 [Page 2] Internet-Draft Proxy Mobile IPv6 February 2008 6.9.1. Binding Registrations . . . . . . . . . . . . . . . .3942 6.9.2. Router Solicitation Messages . . . . . . . . . . . . .4549 6.9.3. Default-Router Lifetime . . . . . . . . . . . . . . . 50 6.9.4. Retransmissions and Rate Limiting . . . . . . . . . .4551 6.10. Routing Considerations . . . . . . . . . . . . . . . . . .4651 6.10.1. Transport Network . . . . . . . . . . . . . . . . . .4652 6.10.2. Tunneling & Encapsulation Modes . . . . . . . . . . .4652 6.10.3.Routing State . . . . . . . . . . . . . . . . . . . . 47 6.10.4.Local Routing . . . . . . . . . . . . . . . . . . . .48 Gundavelli, et al. Expires June 27, 2008 [Page 2] Internet-Draft Proxy Mobile IPv6 December 2007 6.10.5.53 6.10.4. Tunnel Management . . . . . . . . . . . . . . . . . .49 6.10.6.53 6.10.5. Forwarding Rules . . . . . . . . . . . . . . . . . . .4953 6.11. Supporting DHCPv6 based Address Configuration on the Access Link . . . . . . . . . . . . . . . . . . . . . . .5055 6.12. Home Network Prefix Renumbering . . . . . . . . . . . . .5156 6.13. Mobile Node Detachment Detection and Resource Cleanup . .5156 6.14. Allowing network access to other IPv6 nodes . . . . . . .5257 7. Mobile Node Operation . . . . . . . . . . . . . . . . . . . .5357 7.1. Moving into a Proxy Mobile IPv6 Domain . . . . . . . . . .5357 7.2. Roaming in the Proxy Mobile IPv6 Domain . . . . . . . . .54 7.3. IPv6 Host Protocol Parameters . . . . . . . . . . . . . . 5458 8. Message Formats . . . . . . . . . . . . . . . . . . . . . . .5559 8.1. Proxy Binding Update Message . . . . . . . . . . . . . . .5659 8.2. Proxy Binding Acknowledgement Message . . . . . . . . . .5761 8.3. Home Network Prefix Option . . . . . . . . . . . . . . . .5862 8.4.Access Technology TypeHandoff Indicator Option . . . . . . . . . . . . . .60. . . 63 8.5. Access Technology Type Option . . . . . . . . . . . . . . 64 8.6. Mobile Node Interface Identifier Option . . . . . . . . .61 8.6.66 8.7. Link-local Address Option . . . . . . . . . . . . . . . .62 8.7.67 8.8. Timestamp Option . . . . . . . . . . . . . . . . . . . . .63 8.8.67 8.9. Status Values . . . . . . . . . . . . . . . . . . . . . .6468 9. Protocol Configuration Variables . . . . . . . . . . . . . . .6670 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .6771 11. Security Considerations . . . . . . . . . . . . . . . . . . .6872 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .6973 13. References . . . . . . . . . . . . . . . . . . . . . . . . . .6973 13.1. Normative References . . . . . . . . . . . . . . . . . . .6973 13.2. Informative References . . . . . . . . . . . . . . . . . .7074 Appendix A. Proxy Mobile IPv6 interactions with AAA Infrastructure . . . . . . . . . . . . . . . . . . .7175 Appendix B. Supporting Shared-Prefix Model using DHCPv6 . . . . .7175 Appendix C. Routing State . . . . . . . . . . . . . . . . . . . . 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .7277 Intellectual Property and Copyright Statements . . . . . . . . . .74 Gundavelli,79 Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 3] Internet-Draft Proxy Mobile IPv6December 2007February 2008 1. Introduction IP mobility for IPv6 hosts is specified in Mobile IPv6 [RFC-3775]. Mobile IPv6 requires client functionality in the IPv6 stack of a mobile node. Exchange of signaling messages between the mobile node and home agent enables the creation and maintenance of a binding between the mobile node's home address and its care-of-address. Mobility as specified in [RFC-3775] requires the IP host to send IP mobility management signaling messages to theHome Agent,home agent, which is located in the network. Network-based mobility is another approach to solving the IP mobility challenge. It is possible to support mobility for IPv6 nodes without host involvement by extending Mobile IPv6 [RFC-3775] signaling messages between a network node andreusing thea home agent. This approach to supporting mobility does not require the mobile node to be involved in the exchange of signaling messages between itself and theHome Agent.home agent. A proxy mobility agent in the network performs the signaling with the home agent and does the mobility management on behalf of the mobile node attached to the network. Because of the use and extension of Mobile IPv6 signaling and home agent functionality, this protocol is referred to as Proxy Mobile IPv6 (PMIPv6). Network deployments which are designed to support mobility would be agnostic to the capability in the IPv6 stack of the nodes which it serves. IP mobility for nodes which have mobile IP client functionality in the IPv6 stack as well as thosehostsnodes which do not, would be supported by enabling Proxy Mobile IPv6 protocol functionality in the network. The advantages of developing a network based mobility protocol based on Mobile IPv6 are: o Reuse of home agent functionality and the messages/format used in mobility signaling. Mobile IPv6 is a mature protocol with several implementations that have undergone interoperability testing. o A common home agent would serve as the mobility agent for all types of IPv6 nodes. The problem statement and the need for a network based mobility protocol solution has been documented in [RFC-4830]. Proxy Mobile IPv6 is a solution that addresses these issues and requirements. 2. Conventions & TerminologyGundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 4] Internet-Draft Proxy Mobile IPv6December 2007February 2008 2.1. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC-2119]. 2.2. Terminology All the general mobility related terms used in this document are to be interpreted as defined in the Mobile IPv6 base specification [RFC- 3775]. This document adopts the terms, Local Mobility Anchor (LMA) and Mobile Access Gateway (MAG) from the NETLMM Goals document [RFC- 4831]. This document also provides the following context specific explanation to the following terms used in this document. Proxy Mobile IPv6 Domain (PMIPv6-Domain) Proxy Mobile IPv6 domain refers to the network where the mobility management of a mobile node is handled using the Proxy Mobile IPv6 protocol as defined in this specification. The Proxy Mobile IPv6 domain includes local mobility anchors and mobile access gateways between which security associations can be setup and authorization for sending Proxy Binding Updates on behalf of the mobile nodes can be ensured. Local Mobility Anchor (LMA) Local Mobility Anchor is the home agent for the mobile node in the Proxy Mobile IPv6 domain. It is the topological anchor point for the mobile node's home network prefix and is the entity that manages the mobile node's binding state. The local mobility anchor has the functional capabilities of a home agent as defined in Mobile IPv6 base specification [RFC-3775] with the additional capabilities required for supporting Proxy Mobile IPv6 protocol as defined in this specification. Mobile Access Gateway (MAG) Mobile Access Gateway is a function that manages the mobility related signaling for a mobile node that is attached to its access link. It is responsible for tracking the mobile node's movementsonto and from the access link and for signaling the mobile node's local mobility anchor.Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 5] Internet-Draft Proxy Mobile IPv6December 2007February 2008 Mobile Node (MN) Throughout this document, the term mobile node is used to refer to an IP host or router whose mobility is managed by the network. The mobile node may be operating in IPv6 mode, IPv4 mode or in IPv4/IPv6 dual mode. The mobile node is not required to participate in any IP mobility related signaling for achieving mobility for an IP address that is obtained in that Proxy Mobile IPv6 domain.This document further uses explicit text when referring to a mobile node that is involved in mobility related signaling as per the Mobile IPv6 specification [RFC-3775].LMA Address (LMAA) The address that is configured on the interface of the local mobility anchor and is the transport endpoint of the bi- directional tunnel established between the local mobility anchor and the mobile access gateway. This is the address to where the mobile access gateway sends the Proxy Binding Update messages. When supporting IPv4 traversal, i.e., when the network between the local mobility anchor and the mobile access gateway is an IPv4 network, this address will be an IPv4 address and will be referred to as IPv4-LMAA, as specified in [ID-IPV4-PMIP6]. Proxy Care-of Address (Proxy-CoA) Proxy-CoA is the address configured on the interface of the mobile access gateway and is the transport endpoint of the tunnel between the local mobility anchor and the mobile access gateway. The local mobility anchor views this address as the Care-of Address of the mobile node and registers it in the Binding Cache entry for that mobile node. When the transport network between the mobile access gateway and the local mobility anchor is an IPv4 network and if the care-of address that is registered at the local mobility anchor is an IPv4 address, the term, IPv4-Proxy-CoA is used, as specified in [ID-IPV4-PMIP6]. Mobile Node's Home Address (MN-HoA) MN-HoA isthe home address of a mobile node in a Proxy Mobile IPv6 domain. It isan address fromitsa mobile node's home network prefixobtained by a mobile nodein a Proxy Mobile IPv6 domain. The mobile nodecan continuewill be able to use this address as long as it is attached to the access network that is in the scope of that Proxy Mobile IPv6 domain. Unlike in Mobile IPv6 where the home agent is aware of the home address of the mobile node, in Proxy Mobile IPv6, the mobility entities are only aware of the mobile node's home network prefix and are not always aware of the exact address(es) that the mobile node configured on its interface from that prefix. Mobile Node's Home Network Prefix (MN-HNP)Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 6] Internet-Draft Proxy Mobile IPv6December 2007February 2008 This is the on-link IPv6 prefix that is always present in the Router Advertisements that the mobile node receives when it is attached to any of the access links in that Proxy Mobile IPv6 domain. This home network prefix is topologically anchored at the mobile node's local mobility anchor. The mobile node configures its interface with an address from this prefix. If the mobile node connects to the Proxy Mobile IPv6 domain through multiple interfaces, simultaneously, each of the connected interface will be assigned a unique home network prefix and under a different mobility session. Mobile Node's Home Link This is the link on which the mobile node obtained its Layer-3 address configuration for the attached interface after it moved into that Proxy Mobile IPv6 domain. This is the link that conceptually follows the mobile node. The network will ensure the mobile node always sees this link with respect to the layer-3 network configuration, on any access link that it attaches to in that Proxy Mobile IPv6 domain. Multihomed Mobile Node A mobile node that connects to the Proxy Mobile IPv6 domain through more than one interface and uses these interfaces simultaneously is referred to as a multihomed mobile node. Mobile Node Identifier (MN-Identifier) The identity of a mobile node in the Proxy Mobile IPv6 domain. This is the stable identifier of a mobile node that the mobility entities in a Proxy Mobile IPv6 domain can always acquire and use it for predictably identifying a mobile node. This is typically an identifier such as NAI or other identifier such as a MAC address. Mobile Node Interface Identifier (MN-Interface-Identifier) The interface identifier that identifies a given interface of a mobile node. For those interfaces that have a layer-2 identifier, the interface identifier can be based on that layer-2 identifier. The interface identifier in some cases is generated by the mobile node and conveyed to the access router or the mobile access gateway. In some cases, there might not be any interface identifier associated with the mobile node's interface. Policy ProfileGundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 7] Internet-Draft Proxy Mobile IPv6December 2007February 2008 Policy Profile is an abstract term for referring to a set of configuration parameters that are configured for a given mobile node. The mobility entities in the Proxy Mobile IPv6 domain require access to these parameters for providing the mobility management to a given mobile node. The specific details on how the network entities obtain this policy profile is outside the scope of this document. Proxy Binding Update (PBU) A binding registration request message sent by a mobile access gateway to a mobile node's local mobility anchor for establishing a binding between the mobile node's MN-HNP and the Proxy-CoA. Proxy Binding Acknowledgement (PBA) A binding registration reply message sent by a local mobility anchor in response to a Proxy Binding Update request message that it received from a mobile access gateway. 3. Proxy Mobile IPv6 Protocol Overview This specification describes a network-based mobility management protocol. It is called Proxy Mobile IPv6 and is based on Mobile IPv6 [RFC-3775]. Proxy Mobile IPv6 protocol is intended for providing network-based IP mobility management support to a mobile node, without requiring the participation of the mobile node in any IP mobility related signaling. The mobility entities in the network will track the mobile node's movements and will initiate the mobility signaling and setup the required routing state. The core functional entities in the NETLMM infrastructure are the Local Mobility Anchor (LMA) and the Mobile Access Gateway (MAG). The local mobility anchor is responsible for maintaining the mobile node's reachability state and is the topological anchor point for the mobile node's home network prefix. The mobile access gateway is the entity that performs the mobility management on behalf of a mobile node and it resides on the access link where the mobile node is anchored. The mobile access gateway is responsible for detecting the mobile node's movementson itsto and from the access link and forsendinginitiating binding registrations to the mobile node's local mobility anchor. The architecture of a Proxy Mobile IPv6 domain is shown in Figure 1.Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 8] Internet-Draft Proxy Mobile IPv6December 2007February 2008 +----+ +----+ |LMA1| |LMA2| +----+ +----+ LMAA1 -> | | <-- LMAA2 | | \\ //\\ \\ // \\ \\ // \\ +---\\------------- //------\\----+ ( \\ IPv4/IPv6 // \\ ) ( \\ Network // \\ ) +------\\--------//------------\\-+ \\ // \\ \\ // \\ \\ // \\ Proxy-CoA1--> | | <-- Proxy-CoA2 +----+ +----+ |MAG1|-----{MN2} |MAG2| +----+ | +----+ | | | MN-HoA1 --> | MN-HoA2 | <-- MN-HoA3 {MN1} {MN3} Figure 1: Proxy Mobile IPv6 Domain Once a mobile node enters a Proxy Mobile IPv6 domain and attaches to an access link, the mobile access gateway on that access link, after identifying the mobile node and acquiring its identity, will determine if the mobile node is authorized for the network-based mobility management service. If the network determines that the network-based mobility management service needs to be offered to that mobile node, the network will ensure that the mobile node using any of the address configuration mechanisms permitted by the network will be able to obtain the address configuration on the connected interface and move anywhere in that Proxy Mobile IPv6 domain. The obtained address configuration includes the address(es) from its home network prefix, the default- router address on the link and other related configuration parameters. From the perspective of the mobile node, the entire Proxy Mobile IPv6 domain appears as a single link, the network ensures that the mobile node believes it is always on the same link where it obtained its initial address configuration, even afterGundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 9] Internet-Draft Proxy Mobile IPv6December 2007February 2008 changing its point of attachment in that network. The mobile node may be operating in an IPv4-only mode, IPv6-only mode or in dual IPv4/IPv6 mode. Based on what is enabled in the network for that mobile node, the mobile node will be able to obtain an IPv4, IPv6 or dual IPv4/IPv6 addresses and move anywhere in that Proxy Mobile IPv6 domain. However, the specific details related to the IPv4 addressing or IPv4 transport support are specified in the companion document [ID-IPV4-PMIP6]. If the mobile node connects to the Proxy Mobile IPv6 domain, through multiple interfaces and over multiple access networks, the network will allocate a unique home network prefix for each of the connected interfaces and the mobile node will be able to configure an address(es) on those interfaces from the respective home network prefixes.IfHowever, if the mobile node performsa handoveran handoff from one interface to anotherinand if thesame Proxy Mobile IPv6 domain, thenlocal mobility anchor receives an handoff hint from the serving mobile access gateway about the same, the local mobility anchor will assign the same prefix to the newinterface, if it receives the handover hints from the mobile access gateway in the signaling messages. Gundavelli,interface. Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 10] Internet-Draft Proxy Mobile IPv6December 2007February 2008 +-----+ +-----+ +-----+ | MN | | MAG | | LMA | +-----+ +-----+ +-----+ | | | MN Attached | | | | | | MN Attached Event | | (Acquire MN-Id and Profile) | | | | | |----- PBU ----------->| | | | | | Accept PBU | | (Allocate MN-HNP, Setup BCE and Tunnel) | | | | |<--------- PBA -------| | | | | Accept PBA | | (Setup Tunnel and Routing) | | | | | |==== Bi-Dir Tunnel ===| | | | |--- Rtr Sol --------->| | | | | |<------- Rtr Adv -----| | | | | IP Address | | Configuration | | | | | Figure 2: Mobile Node Attachment - Signaling Call Flow Figure 2 shows the signaling call flow when the mobile node enters the Proxy Mobile IPv6 domain. For updating the local mobility anchor about the current location of the mobile node, the mobile access gateway sends a Proxy Binding Update message to the mobile node's local mobility anchor. Upon accepting this Proxy Binding Update message, the local mobility anchor sends a Proxy Binding Acknowledgement message including the mobile node's home network prefix. It also creates the Binding Cache entry and establishes a bi-directional tunnel to the mobile access gateway.Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 11] Internet-Draft Proxy Mobile IPv6December 2007February 2008 The mobile access gateway on receiving the Proxy Binding Acknowledgement message sets up a bi-directional tunnel to the local mobility anchor and sets up the data path for the mobile node's traffic. At this point the mobile access gateway will have all the required information for emulating the mobile node's home link. It sends Router Advertisement messages to the mobile node on the access link advertising the mobile node's home network prefix as the hosted on-link-prefix. The mobile node on receiving these Router Advertisement messages on the access link will attempt to configure its interface either using stateful or stateless address configuration modes, based on the modes that are permitted on that access link. At the end of a successful address configuration procedure, the mobile node will end up with an address from its home network prefix. Once the address configuration is complete, the mobile node has a valid address from its home network prefix at the current point of attachment. The serving mobile access gateway and the local mobility anchor also have proper routing states for handling the traffic sent to and from the mobile node using an address from its home network prefix. The local mobility anchor, being the topological anchor point for the mobile node's home network prefix, receives any packets that are sent by any correspondent node to the mobile node. The local mobility anchor forwards these received packets to the mobile access gateway through the bi-directional tunnel. The mobile access gateway on other end of the tunnel, after receiving the packet, removes the outer header and forwards the packet on the access link to the mobile node. The mobile access gateway typically acts as a default router on the access link. Any packet that the mobile node sends to any correspondent node will be received by the mobile access gateway and will be sent to its local mobility anchor through the bi-directional tunnel. The local mobility anchor on the other end of the tunnel, after receiving the packet, removes the outer header and routes the packet to the destination.Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 12] Internet-Draft Proxy Mobile IPv6December 2007February 2008 +-----+ +-----+ +-----+ +-----+ | MN | |p-MAG| | LMA | |n-MAG| +-----+ +-----+ +-----+ +-----+ | | | | | |==Bi-Dir Tunnel=| | MN Detached | | | | MN Detached Event | | | | | | | |-- DeReg PBU -->| | | | | | | | Accept PBU | | | (Start MinDelayBeforeBCEDelete Timer) | | | | | |<-------- PBA --| | | | | | MN Attached | | | | | | MN Attached Event | | | (Acquire MN-Id and Profile) .... Registration steps as in fig 2. .... | | |==Bi-Dir Tunnel=| |--- Rtr Sol ------------------------------------->| | | | | |<------------------------------------ Rtr Adv ----| | | | | MN retains HoA/HNP | | | | Figure 3: Mobile Node Handoff - Signaling Call Flow Figure 3 shows the signaling call flow for the mobile node's handoff from previously attached mobile access gateway (p-MAG) to the newly attached mobile access gateway (n-MAG). This call flow reflects only a specific message ordering, it is possible the registration message from the n-MAG may arrive before the de-registration message from the p-MAG arrives. After obtaining the initial address configuration in the Proxy Mobile IPv6 domain, if the mobile node changes its point of attachment, the mobile access gateway on the previous link will detect the mobile node's detachment from the link and will signal the local mobility anchor and will remove the binding and routing state for that mobile node. However, the local mobility anchor upon accepting the request Gundavelli (Editor), et al. Expires August 6, 2008 [Page 13] Internet-Draft Proxy Mobile IPv6 February 2008 will wait for certain amount of time before it deletes the binding, for allowing a smooth handoff. The mobile access gateway on the new access link upon detecting theGundavelli, et al. Expires June 27, 2008 [Page 13] Internet-Draft Proxy Mobile IPv6 December 2007mobile node on its access link will signal the local mobility anchor for updating the binding state. Once that signaling is complete, the mobile node will continue to receive the Router Advertisements containing its home network prefix, making it believe it is still on the same link and it will use the same address configuration on the new access link. 4. Proxy Mobile IPv6 Protocol Security The signaling messages, Proxy Binding Update and Proxy Binding Acknowledgement, exchanged between the mobile access gateway and the local mobility anchor MUST be protected using end-to-end security association(s) offering integrity and data origin authentication. The mobile access gateway and the local mobility anchor MUST implement IPsec for protecting the Proxy Mobile IPv6 signaling messages [RFC-4301]. That is, IPsec isthe default security mechanism for securing the signaling messages. However in certain deployments of this protocol, othermandatory to implement securitymechanisms MAY be applied and the signaling messages must be protected using the semantics provided by that respectivemechanism.The specification of the other security mechanisms are beyond the scope of this documentHowever, additional documents may specify alternative mechanisms. IPsec ESP [RFC-4303] in transport mode with mandatory integrity protection SHOULD be used for protecting the signaling messages. Confidentiality protection of these messages is not required. IKEv2 [RFC-4306] SHOULD be used to setup security associations between the mobile access gateway and the local mobility anchor to protect the Proxy Binding Update and Proxy Binding Acknowledgement messages. The mobile access gateway and the local mobility anchor can use any of the authentication mechanisms, as specified in IKEv2, for mutual authentication. The Mobile IPv6 specification [RFC-3775] requires the home agent to prevent a mobile node from creating security associations or creating binding cache entries for another mobile node's home address. In the protocol described in this document, the mobile node is not involved in creating security associations for protecting the signaling messages or sending binding updates. Therefore, the local mobility anchor MUSTallow onlyrestrict the creation and manipulation of proxy bindings to specifically authorized mobile access gatewaysto create binding cache entries on behalf of the mobile nodes.and prefixes. Theactual mechanism by which thelocal mobility anchorverifies if a specific mobile access gateway is authorizedMUST be locally configurable tosend Proxy Binding Updates on behalf ofauthorize such specific combinations. Additional mechanisms such as amobile node ispolicy store or AAA may be employed, but these are outside the scope of thisdocument. One possible way this could be achieved is by sending a query to the Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 14] Internet-Draft Proxy Mobile IPv6December 2007 policy store, such as AAA.February 2008 specification. 4.1. Peer Authorization Database Entries This section describes PAD entries [RFC-4301] on the mobile access gateway and the local mobility anchor. The PAD entries are only example configurations. Note that the PAD is a logical concept and a particular mobile access gateway or a local mobility anchor implementation can implement the PAD in any implementation specific manner. The PAD state may also be distributed across various databases in a specific implementation. mobile access gateway PAD: - IF remote_identity = lma_identity_1 Then authenticate (shared secret/certificate/EAP) and authorize CHILD_SA for remote address lma_addres_1 local mobility anchor PAD: - IF remote_identity = mag_identity_1 Then authenticate (shared secret/certificate/EAP) and authorize CHILD_SAs for remote address mag_address_1 Figure 4: PAD Entries The list of authentication mechanisms in the above examples is not exhaustive. There could be other credentials used for authentication stored in the PAD. 4.2. Security Policy Database Entries This section describes the security policy entries [RFC-4301] on the mobile access gateway and the local mobility anchor required to protect the Proxy Mobile IPv6 signaling messages. The SPD entries are only example configurations. A particular mobile access gateway or a local mobility anchor implementation could configure different SPD entries as long as they provide the required security. In the examples shown below, the identity of the mobile access gateway is assumed to be mag_1, the address of the mobile access gateway is assumed to be mag_address_1, and the address of the local mobility anchor is assumed to be lma_address_1.Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 15] Internet-Draft Proxy Mobile IPv6December 2007February 2008 mobile access gateway SPD-S: - IF local_address = mag_address_1 & remote_address = lma_address_1 & proto = MH & local_mh_type = BU & remote_mh_type = BA Then use SA ESP transport mode Initiate using IDi = mag_1 to address lma_address_1 local mobility anchor SPD-S: - IF local_address = lma_address_1 & remote_address = mag_address_1 & proto = MH & local_mh_type = BA & remote_mh_type = BU Then use SA ESP transport mode Figure 5: SPD Entries 5. Local Mobility Anchor Operation The local mobility anchor MUST support the home agent function as defined in [RFC-3775] and additionally the extensions defined in this specification. A home agent with these modifications and enhanced capabilities for supporting Proxy Mobile IPv6 protocol is referred to as the local mobility anchor. This section describes the operational details of the local mobility anchor. 5.1. Extensions to Binding Cache Entry Data Structure Every local mobility anchor MUST maintain a Binding Cache entry for each currently registered mobile node. Binding Cache entry is a conceptual data structure, described in Section 9.1 [RFC-3775]. For supporting this specification, the Binding Cache Entry data structure needs to be extended with the following additional fields. o A flag indicating whether or not this Binding Cache entry is created due to a proxy registration. This flag is enabled for Binding Cache entries that are proxy registrations and is turned off for all otherentries that are created due to the registrations directly sent by the mobile node.entries. o The identifier of the registered mobile node, MN-Identifier. This identifier is obtained from the Mobile Node Identifier Option [RFC-4283] present in the received Proxy Binding Update request.Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 16] Internet-Draft Proxy Mobile IPv6December 2007February 2008 o The interface identifier of the mobile node's connected interface on the access link. This identifier can be acquired from the Mobile Node Interface Identifier option, present in the received Proxy Binding Update request. If the option was not present in the request,thisthe value MUST be set to ALL_ZERO. o The Link-local address of the mobile node on the interface attached to the access link. This is obtained from the Link-local Address option, present in the Proxy Binding Update request. If the option was not present in the request, the value MUST be set to ALL_ZERO. o The IPv6 home network prefixofthat is assigned to theregisteredmobilenode.node's connected interface. The home network prefix of the mobile node may have been statically configured in the mobile node's policy profile, or, it may have been dynamically allocated by the local mobility anchor. The IPv6 home network prefix also includes the corresponding prefix length. o The interface identifier (If-Id) of the bi-directional tunnelestablishedbetween the local mobility anchor and the mobile access gateway where the mobile node is currently anchored. This is internal to the local mobility anchor. The tunnel interface identifier is acquired during the tunnel creation. o The access technologythroughtype, using which the mobile node is currentlyconnected.attached. This is obtained from the Access Technology Type option, present in the Proxy Binding Updatemessage.request. o The 64-bit timestamp value of the most recently accepted Proxy Binding Update request sent for this mobile node. This isobtained fromthe time-of-day on the local mobility anchor, when the message was received. If the Timestampoption,option is not present in therequest.Proxy Binding Update request (i.e., when sequence number based scheme is in use), the value MUST be set to ALL_ZERO. Typically, theMN-Identifiermobile node's home network prefix is the key for locating a Binding Cacheentry. However,entry in all cases except whensupporting multihomingthereMAY be more than one Binding Cache entry withhas been an handoff of thesame MN-Identifiermobile node's session to a new mobile access gateway andinthat mobile access gateway is unaware of the home network prefix that was assigned to the handed of session. In suchcaseshandoff cases, the Binding Cache entry can be locatedusing any ofunder thefollowing key combinations: o MN-Identifier, MN-HNP o MN-Identifier, Proxy-CoA o MN-Identifier, MN-Interface-Identifier o MN-Identifier, Access Technology Type (When MN-Interface- Identifier is not present) Gundavelli,considerations specified in Section 5.4.1. Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page 17] Internet-Draft Proxy Mobile IPv6December 2007February 2008 5.2. Supported Home Network Prefix Models This specification supports Per-MN-Prefix model and does not support Shared-Prefix model. As per the Per-MN-Prefix model, there will be a unique home network prefix assigned to each mobile node and no other node shares an address from that prefix. The assigned prefix is unique to a mobile node and also unique to a given interface of the mobile node. If the mobile node attaches to the Proxy Mobile IPv6 domain through multiple interfaces and simultaneously, each of those connected interfaces will be assigned a different prefix. The mobile node's home network prefix is always hosted on the access link where the mobile node is anchored. Conceptually, the entire home network prefix follows the mobile node as it moves within the Proxy Mobile IPv6 domain. The local mobility anchor is not required to perform any proxy ND operations [RFC-4861] for defending the mobile node's home address on the home link. However, from the routing perspective, the home network prefix is topologically anchored on the local mobility anchor. 5.3. Signaling Considerations This section provides the rules for processing the signaling messages. The processing rules specified in this section and other related sections are chained and are in a specific order. When applying these considerations for processing the signaling messages, the specified order MUST be maintained. 5.3.1. Processing Binding RegistrationsUpon receiving a1. The received Proxy Binding Updaterequestmessage (a Binding UpdateRequestmessage with the 'P' flag set)from a mobile access gateway on behalf of a mobile node, the local mobility anchorMUSTprocess the request as defined in Section 10.3 [RFC-3775]; additionally the following considerations mustbeapplied. 1. The local mobility anchor MUST observe the rulesauthenticated as described in Section9.2 [RFC-3775]4.0. When IPsec is used for message authentication, the SPI in the IPsec header [RFC-4306] of the received packet is needed for locating the security association, for authenticating the Proxy Binding Update message. 2. The local mobility anchor MUST observe the rules described in Section 9.2 [RFC-3775] when processing MobilityHeadersHeader in the received Proxy Binding Update request.2.Additionally, the rules specified in Section 10.3 [RFC-3775] MUST be applied when processing this message. 3. The local mobility anchor MUST ignore the check, specified in Section 10.3.1 [RFC-3775], related to the presence of Home Gundavelli (Editor), et al. Expires August 6, 2008 [Page 18] Internet-Draft Proxy Mobile IPv6 February 2008 Address destination option in the Proxy Binding Update request. 4. The local mobility anchor MUST identify the mobile node from the identifier present in the Mobile Node Identifier option [RFC- 4283] of the Proxy Binding Update request. If the Mobile Node Identifier option is not present in the Proxy Binding Update request, the local mobility anchor MUST reject the request andGundavelli, et al. Expires June 27, 2008 [Page 18] Internet-Draft Proxy Mobile IPv6 December 2007send a Proxy Binding Acknowledgement message with Status field set to MISSING_MN_IDENTIFIER_OPTION (Missing mobile nodeidentifier)identifier option) and the identifier in the Mobile Node Identifier Option carried in the message MUST be set to a zero length identifier.3.5. The local mobility anchor MUST apply the required policy checks, as explained in Section 4.0, to verify the sender is a trusted mobile access gateway, authorized to send Proxy Binding Update requests on behalf of this mobile node. 6. If the local mobility anchor determines that the requesting node is not authorized to send Proxy Binding Update requests for the identified mobile node, it MUST reject the request and send a Proxy Binding Acknowledgement message with Status field set to MAG_NOT_AUTHORIZED_FOR_PROXY_REG (not authorized to send proxy binding registrations). 7. If the local mobility anchor cannotauthorizeidentify the mobile node based on the identifier present in the Mobile Node Identifier option [RFC-4283]present in theof Proxy Binding Update request, it MUST reject theProxy Binding Updaterequest and send a Proxy Binding Acknowledgement message with Status field set to 133 (Nothome agentlocal mobility anchor for this mobile node).4.8. If the local mobility anchor determines that the mobile node is not authorized for the network-based mobility management service, it MUST reject the request and send a Proxy Binding Acknowledgement message with Status field set to PROXY_REG_NOT_ENABLED (Proxy Registration not enabled).5.9. The local mobility anchor MUSTignoreapply thecheck,considerations specified in Section10.3.1 [RFC-3775], related to5.5, for processing thepresence of Home Address destinationSequence Number field and the Timestamp option (if present), in the Proxy Binding Update request.6. The local mobility anchor MUST authenticate the Proxy Binding Update request as described in Section 4.0. When IPsec is used for message authentication, the SPI in the IPsec header [RFC- 4306] of10. If thereceived packetHome Network Prefix option (containing either ALL_ZERO or some prefix value) isneeded for locating the security association, for authenticating the Proxy Binding Update request. 7. The local mobility anchor MUST apply the required policy checks, as explainednot present inSection 4.0, to verifythesender is a trusted mobile access gateway, authorized to sendProxy Binding Updaterequests on behalf of this mobile node. 8. Ifrequest, the local mobility anchordetermines that the requesting node is not authorized to send Proxy Binding Update requests, itMUST reject the request and send a Proxy Binding Acknowledgement message with Status field set toMAG_NOT_AUTHORIZED_FOR_PROXY_REG (Not authorized to send proxy registrations). 9.MISSING_HOME_NETWORK_PREFIX_OPTION (Missing home network Gundavelli (Editor), et al. Expires August 6, 2008 [Page 19] Internet-Draft Proxy Mobile IPv6 February 2008 prefix option). 11. If theHome Network PrefixHandoff Indicator option is not present in the Proxy Binding Update request, the local mobility anchor MUST reject the request and send a Proxy Binding Acknowledgement message with Status field set toMISSING_HOME_NETWORK_PREFIX_OPTIONMISSING_HANDOFF_INDICATOR_OPTION (Missingmobile node's home network prefixhandoff indicator option).10.12. If the Access Technology Type option is not present in the Proxy Binding Update request, the local mobility anchor MUST rejectGundavelli, et al. Expires June 27, 2008 [Page 19] Internet-Draft Proxy Mobile IPv6 December 2007the request and send a Proxy Binding Acknowledgement message with Status field set to MISSING_ACCESS_TECH_TYPE_OPTION (Missingmobile node'saccess technologytype). 11. The local mobility anchor MUST apply the considerationstype option). 13. Considerations specified in Section5.5,5.4.1 MUST be applied forprocessing the Sequence Number field and the Timestamp option, inperforming theProxyBindingUpdate request. 12. The local mobility anchor MUST use the identifier from the Mobile Node Identifier Option [RFC-4283] presentCache entry existence test. If those checks specified in Section 5.4.1, result in associating the received Proxy Binding Update requestand MUST apply multihomingto a new mobility session creation request, considerationsspecified infrom Section5.4 for performing the5.3.2 (Initial BindingCache entry existence test or for identifying the mobility session.Registration - New Mobility Session), MUST be applied. If those checks result in associating theentry does not exist, the local mobility anchor MUST consider thisrequestasto aninitial binding registration request. If the entry exists, the localexisting mobilityanchor MUST consider this request as a binding re-registration request. However, fromsession, theperspective offollowing checks determine themobile access gatewaynext set of processing rules thatsentneeds to be applied. * If the Handoff Indicator field in the Handoff Indicator option present in therequest, this binding re-registrationrequestmayis set to a value of 5 (Handoff state not changed), considerations from Section 5.3.3 (Binding Lifetime Extension- No handoff) MUST bean initialapplied. * If the received Proxy Binding Update requestafterhas themobile node's attachment to that mobile access gateway.lifetime value of zero, considerations from Section 5.3.5 (Binding De- Registration) MUST be applied. * For all other cases, considerations from Section 5.3.4 (Binding Lifetime Extension - After handoff) MUST be applied. 14. When sending the Proxy Binding Acknowledgement message with any Status field value, the message MUST be constructed as specified in Section 5.3.6. 5.3.2. Initial BindingRegistration:Registration (New Mobility Session) 1. If the Home Network Prefix option present in the Proxy Binding Update request has the value0::/0,set to ALL_ZERO, the local mobility anchorSHOULDMUST allocate a prefixfor the mobile nodeandsendassign it to aProxy Binding Acknowledgement message including the Home Network Prefix option containingnew mobility session created for theallocated prefix value.mobile node. The local mobility anchor MUST ensure the allocated prefix is not in use by any othernode.node Gundavelli (Editor), et al. Expires August 6, 2008 [Page 20] Internet-Draft Proxy Mobile IPv6 February 2008 or mobility session. 2. If the local mobility anchor is unable to allocateaany home network prefix for the mobile node, it MUST reject the request and send a Proxy Binding Acknowledgement message with Status field set to 130 (Insufficient resources). 3. If the Home Network Prefix option present in the request has a specific prefix hint, the local mobility anchor before accepting that request, MUST ensure the prefix is owned by the local mobility anchor and further the mobile node is authorized to use that prefix. If the mobile node is not authorized to use that prefix, the local mobility anchor MUST reject the request and send a Proxy Binding Acknowledgement message with Status field set to NOT_AUTHORIZED_FOR_HOME_NETWORK_PREFIX (Mobile node not authorized to use that prefix).Gundavelli, et al. Expires June 27, 2008 [Page 20] Internet-Draft Proxy Mobile IPv6 December 20074. Upon accepting the request, the local mobility anchor MUST create a Binding Cache entry for the mobile node. It must set the fields in the Binding Cache entry to the accepted values for thatbinding. If there isregistration. 5. The local mobility anchor MUST establish aLink-local Address option present in the request, the address must be copied to the link-local address field in the Binding Cache entry. 5. Upon accepting the Proxy Binding Update request, the local mobility anchor MUST establish a bi-directional tunnelbi-directional tunnel to the mobile accessgateway, as described in [RFC-2473].gateway (if there does not exist one) that sent the request and setup the routing state. Considerations from Section 5.6mustMUST beapplied. Binding Re-Registration: 1. If the requesting prefix in the Home Network Prefix option is a non 0::/0 value and is different from what is present in the currently active Binding Cache entryapplied forthat mobile node,creating the routing state. 6. The local mobility anchor MUSTreject the request andsendathe Proxy Binding Acknowledgement message with the Status field set to129 (Administratively Prohibited). 2. If there is a Link-local Address option present0 (Proxy Binding Update Accepted). The message MUST be constructed as specified in Section 5.3.6. 5.3.3. Binding Lifetime Extension (No handoff) 1. Upon accepting the Proxy Binding Update requestwith a value other than ALL_ZERO (not set), and upon acceptingfor extending the bindingre-registration request,lifetime, received from the same mobile access gateway that last updated the binding (i.e., when there is no handoff), the local mobility anchor MUST update the Binding Cache entry with the accepted registration values. However, if the link- local address value in the Link-local address option is ALL_ZERO value, the link-local address field in the Binding Cache entrytoMUST NOT be updated. 2. The local mobility anchor MUST send theaddress value received inProxy Binding Acknowledgement message with therequest. 3.Status field set to 0 (Proxy Binding Update Accepted). The message MUST be constructed as specified in Section 5.3.6. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 21] Internet-Draft Proxy Mobile IPv6 February 2008 5.3.4. Binding Lifetime Extension (After handoff) 1. Upon acceptingathe Proxy Binding Update request for extending thelifetime of a currently activebindingforlifetime, received from a new mobilenode,access gateway where the mobile node's session is handed off, the local mobility anchor MUST update theexistingBinding Cache entryfor this mobile node. Unless there exists an established bi-directional tunnel to the mobile access gatewaywith thesame transport and encapsulation mode,accepted registration values. However, if the link-local address value in the Link-local address option is ALL_ZERO value, the link-local address field in the Binding Cache entry MUST NOT be updated. 2. The local mobility anchor MUSTcreate a tunnel toremove the previously created route for the mobileaccess gateway, as described in [RFC-2473] and also deletenode's home network prefix. Additionally, if there are no other mobile node's sessions sharing theexistingtunnelrouteto the previous mobile accessgateway. Itgateway, the tunnel MUSTalso sendbe deleted. 3. The local mobility anchor MUST establish aProxy Binding Acknowledgement messagebi-directional tunnel to the mobile access gatewaywith the Status field set to 0 (Proxy Binding Update Accepted). Binding De-Registration: 1. If the received Proxy Binding Update request with the lifetime value of zero and the prefix inthat sent theHome Network Prefix option is a non 0::/0 value and is differentrequest. Considerations fromwhat is present in the currently active Binding Cache entrySection 5.6 MUST be applied forthat mobile node,creating the routing state. 4. The local mobility anchor MUSTreject the request andsenda Proxy Gundavelli, et al. Expires June 27, 2008 [Page 21] Internet-Draftthe ProxyMobile IPv6 December 2007Binding Acknowledgement message with the Status field set to129 (Administratively Prohibited). 2.0 (Proxy Binding Update Accepted). The message MUST be constructed as specified in Section 5.3.6. 5.3.5. Binding De-Registration 1. If the received Proxy Binding Update request with the lifetime value of zero, has a Source Address in the IPv6 header (or the address in the Alternate Care-of Address option, if the option is present) different from what is present in the Proxy-CoA address field in the Binding Cacheentry existing for that mobile node,entry, the local mobility anchorSHOULDMUST ignore the request.3.2. Upon accepting the Proxy Binding Update requestfor a mobile node,with the lifetime value of zero, the local mobility anchor MUST wait for MinDelayBeforeBCEDelete amount of time, before it deletes themobile node'sBinding Cache entry.Within this wait period, ifHowever, it MUST send thelocal mobility anchor receives aProxy BindingUpdate requestAcknowledgement messagefor the same mobile nodewith thelifetime value of greaterStatus field set to 0 (Proxy Binding Update Accepted). The message MUST be constructed as specified in Section 5.3.6. * During this wait period, the local mobility anchor SHOULD drop the mobile node's data traffic. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 22] Internet-Draft Proxy Mobile IPv6 February 2008 * During this wait period, if the local mobility anchor receives a valid Proxy Binding Update request for the same mobility session with the lifetime value of greater than zero, and if that request is accepted, then the Binding Cache entry MUST NOT be deleted, but must be updated with the newly accepted registrationvalues. The local mobility anchor MUST sendvalues and additionally theProxy Binding Acknowledgement message, immediately upon acceptingwait period should be ended. * By therequest. However, withinend of this wait period, if the local mobility anchordoesdid not receive any validbinding registrationProxy Binding Update request forthat mobile node, then at the end ofthiswait period,mobility session, then it MUST delete themobile node'sBinding Cache entry and remove the routing state created for thatmobile node. In addition, during this MinDelayBeforeBCEDelete wait period, the localmobilityanchor MUST continue to route the mobile node's data traffic.session. 5.3.6. Constructing the Proxy Binding AcknowledgementMessage:Message o The local mobility anchor when sending the Proxy Binding Acknowledgement message to the mobile access gateway MUST construct the message as specified below. IPv6 header (src=LMAA, dst=Proxy-CoA) Mobility header-BA /*P- BA /* P flagis set*/must be set */ Mobility Options -Home Network Prefix Option - Link-local Address Option (optional) - Timestamp Option (optional) -Mobile Node Identifier Option(Mandatory)(mandatory) - Home Network Prefix option (mandatory) - Handoff Indicator option (mandatory) - Access Technology Type option(Mandatory)(mandatory) - Timestamp Option (optional) - Mobile Node Interface Identifier option(Optional) Gundavelli, et al. Expires June 27, 2008 [Page 22] Internet-Draft Proxy Mobile IPv6 December 2007(optional) - Link-local Address option (optional) Figure 6: Proxy Binding Acknowledgement message format o The Source Address field in the IPv6 header of the message MUST be set to the destination address of the received Proxy Binding Update request. o The Destination Address field in the IPv6 header of the message MUST be set to the source address of the received Proxy Binding Update request.o The Home Network PrefixWhen there is no Alternate Care-of Address optionMUST bepresent in theProxy Binding Acknowledgement message. Ifrequest, theoption was not present indestination address is therequest and ifsame as theStatus field value is set to MISSING_HOME_NETWORK_PREFIX_OPTION,Proxy-CoA address, otherwise, thevalue MUST be set to ALL_ZERO. o The Access Technology Type option MUSTaddress may not bepresent. The access technology type valuethe same as the Proxy-CoA. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 23] Internet-Draft Proxy Mobile IPv6 February 2008 o The Mobile Node Identifier option [RFC-4283] MUST be present. The identifier field in the option MUST be copied from theAccess Technology TypeMobile Node Identifier option in the received Proxy Binding Update request. If the option was not present in therequest and ifrequest, theStatus field value is set to MISSING_ACCESS_TECH_TYPE_OPTION,identifier in thevalueoption MUST be set to0.a zero length identifier. o TheMobile Node Interface IdentifierHome Network Prefix optionMAYMUST bepresent, if the same option was present in the corresponding Proxy Binding Update request message. opresent. * If the Status field is set to a value greater than or equal to 128, i.e., if the binding requestwasis rejected, then the prefix value in the Home Network Prefix option MUST be set to the prefix valuefromin thereceivedHome Network Prefixoption.option of the received Proxy Binding Update request. But, if the option was not present in the request, the value in the option MUST be set to ALL_ZERO. * For all other cases, the prefix value in the option MUST be set to the allocated prefix value for thatmobile node.mobility session. o TheLink-local AddressHandoff Indicator option MUST bepresentpresent. The handoff indicator field in theProxy Binding Acknowledgement message if and only ifoption MUST be copied from thesameHandoff Indicator optionwas presentin thecorrespondingreceived Proxy Binding Updaterequest message. orequest. If theStatus field is set to a value greater than or equal to 128, i.e., if the binding requestoption wasrejected, thennot present in the request, thelink- local addressvalue in theLink-local Addressoption MUST be set tothe value from the received Link-local Address option.zero. oIf there is an existing Binding Cache entry for the mobile node with the link-local address value of ALL_ZERO (value not set), or if there was no existing Binding Cache entry, thenThe Access Technology Type option MUST be present. The access technology type field in thelink-local addressoption MUST be copied from theLink-local AddressAccess Technology Type option in the received Proxy Binding Update request.For all other cases, it Gundavelli, et al. Expires June 27, 2008 [Page 23] Internet-Draft Proxy Mobile IPv6 December 2007If the option was not present in the request, the value in the option MUST becopied fromset to zero. o The Timestamp option MUST be present, if themobile node'ssame option was present in the received Proxy BindingCache entry. oUpdate request. Considerations from Section 5.5 must be applied for constructing the Timestamp option. o Theidentifier in theMobile Node Interface Identifier option[RFC-4283]MUST be present, if the same option was present in the received Proxy Binding Update request. The interface identifier value MUST be copied from the Mobile Node Interface Indicator option present in the received Proxy Binding Update request. o The Link-local Address option MUST be present, if the same option was present in the received Proxy Binding Update request. * If theStatus fieldreceived Proxy Binding Update request has the Link-local Address option with any value other than ALL_ZERO, the same value MUST be copied to the Link-local Address option in the Gundavelli (Editor), et al. Expires August 6, 2008 [Page 24] Internet-Draft Proxy Mobile IPv6 February 2008 reply. * If there is no existing Binding Cache entry (i.e., if this is a request for a new mobility session), or if there is an existing Binding Cache entry with the link-local address value set toMISSING_MN_IDENTIFIER_OPTION,ALL_ZERO, then theidentifierlink-local address in theMobile Node Identifier Optionoption MUST beset to a zero length identifier.copied from the Link-local Address option present in the received Proxy Binding Update request. * For all other cases, the link-local address in the option MUST be copied from the Link-local Address field of the Binding Cache entry. o If IPsec is used for protecting the signaling messages, the message MUST be protected, using the security association existing between the local mobility anchor and the mobile access gateway. oTheUnlike in Mobile IPv6 [RFC-3775], the Type 2 Routing header MUST NOT be present in the IPv6 header of the packet. 5.4. Multihoming SupportWhen aThis specification allows mobilenode connectsnodes to connect to a Proxy Mobile IPv6 domain through multiple interfacessimultaneously,and for simultaneous access. Following are thelocal mobility anchorkey aspects of this multihoming support. o When a mobile node connects to a Proxy Mobile IPv6 domain through multiple interfaces and for simultaneous access, the local mobility anchor MUST allocate a unique home network prefix for each of the connected interfaces. o The local mobility anchor MUST manage each of the allocated home network prefixes as part of a separate mobility session, each under a separate Binding Cache entry and with its own lifetime. o The local mobility anchor MUST allow fora handoveran handoff between two different interfaces of the mobile node. In such a case, the home network prefix that is associated with a specific interface identifier of a mobile node will be updated with the new interface identifier. The decision on when to create a new mobility session and when to update an existing mobility session MUST be based on the Handover hint present in the signaling messages and under the considerations specified in this section.The local mobility anchor MUST apply the following multihoming considerations when processing a received Proxy Binding Update request message. Processing De-Registration Message: 1. If the received Proxy Binding Update message has lifetime value of zero, the local mobility anchor MUST verify if there is an Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page24]25] Internet-Draft Proxy Mobile IPv6December 2007 existingFebruary 2008 5.4.1. Binding Cache entry lookup considerations There can be multiple Binding Cache entries forthea given mobilenode, identified by the MN-Identifier and with the Proxy-CoA address matching the source address in the IPv6 header of the received packet. If there existsnode. When doing a lookup for a mobile node's Binding Cacheentry,entry for processing a received Proxy Binding Update request message, the local mobility anchor MUSTconsiderapply themessage as a request for de-registering that specific mobility session. If there does not exist a Binding Cache entry,following multihoming considerations (in themessage MUST be ignored.specified order). These rules are chained with the processing rules specified in Section 5.3. 5.4.1.1. Home Network Prefix Option(Non-Zero Prefix)(NON_ZERO Value) present in therequest:request +=====================================================================+ | Registration/De-Registration Message | +=====================================================================+ | HNP (NON_ZERO Value) | +=====================================================================+ | ATT | +=====================================================================+ | IID Option Present | IID Option Not present | +=====================================================================+ | HI | +==================================+==================================+ | BCE Lookup Key: (Home Network Prefix) | +=====================================================================+ Figure 7: BCE lookup using home network prefix 1. The local mobility anchor MUST verify if there is an existing Binding Cache entryfor the mobile node, identified by the MN- Identifier andwith the home network prefix value matching the prefix value in the Home Network PrefixOptionoption of the received Proxy Binding Update request. [BCE(HNP) == PBU(HNP)] 2. If thereisdoes not exist aMobile Node Interface Identifier Option present inBinding Cache entry (matching therequest, itMN- HNP), the request MUST beignoredconsidered as a request forthis search.creating a new mobility session. 3. If there exists a Binding Cache entrymatching the specified criteria, the local mobility anchor MUST consider the message as a request for updating that specific mobility session. The local mobility anchor upon accepting the request MUST update the existing Binding Cache entry(matching MN-HNP), andassignif thehome network prefix presentmobile node identifier in theBinding Cache entry. If thereentry does notexist a Binding Cache entry matching this specified criteria,match the mobile node identifier in thebelow considerations MUST be applied.Mobile NodeInterfaceIdentifierOption not present inoption of the received Proxy Binding Update request, therequest: 1. Thelocal mobility anchor MUSTverify if there is an existing Binding Cache entry for the mobile node, identified byreject theMN- Identifier andrequest with theinterface identifierStatus field value set toALL_ZERO. 2. If there doesNOT_AUTHORIZED_FOR_HOME_NETWORK_PREFIX (mobile node is notexist a Binding Cache entry, the local mobility anchor upon acceptingauthorized for therequest MUST assign a newrequesting home networkprefix and create a new Binding Cache entry. 3.prefix). [BCE(MN- Identifier) != PBU(MN-Identifier)] Gundavelli (Editor), et al. Expires August 6, 2008 [Page 26] Internet-Draft Proxy Mobile IPv6 February 2008 4. If there exists a Binding Cache entry (matching MN-Identifier and MN-HNP) and ifthe Handoff Indicator field in the Access Technology Type option present in the received Proxy Binding Update message is set to value 1 (Attachment over a new interface), the local mobility anchor upon acceptingany one or more of these below stated conditions match, the request MUSTassign a new home network prefix and createbe considered as anewrequest for updating that Binding Cache entry.4.[BCE(MN-Identifier) == PBU(MN- Identifier)] * If thereexistsis a Mobile Node Interface Identifier option present in the request, and if the interface identifier value in that option matches the interface identifier value in the Binding Cache entry andiftheHandoff Indicatoraccess technology type field in the Access Technology Type option present in thereceived Proxy Binding Update messagerequest matches the access technology type in the Binding Cache entry . [BCE(ATT, MN-Interface-Identifier) == PBU(ATT, MN-Interface-Identifier)] * If the Handoff Indicator field in the Handoff Indicator option present in the request is set toeithera valueGundavelli, et al. Expires June 27, 2008 [Page 25] Internet-Draft Proxy Mobile IPv6 December 2007of 2 (Handoff betweeninterfaces) or 3 (Handoff between mobile access gateways fortwo different interfaces of thesamemobilenode's interface),node). * If there is no Mobile Node Interface Identifier option present in thelocal mobility anchor upon acceptingrequest, therequest MUST updateinterface identifier value in theexistingBinding Cache entryand assignis set to ALL_ZERO, thehome network prefixaccess technology type field in the Access Technology Type option present in theBinding Cache entry. 5. If there exists arequest matches the access technology type in the Binding Cache entry and if the Handoff Indicator field in theAccess Technology TypeHandoff Indicator option present in thereceived Proxy Binding Update messagerequest is set to a value4of 3 (Handoffstate unknown), the local mobility anchor SHOULD wait till the existing Binding Cache entry is de-registered by the previously servingbetween mobile accessgateway, before it assignsgateways for the samehome network prefix or updatesinterface). * If the Proxy-CoA address in theexistingBinding Cacheentry. However, if there is no de-registration message that is received within MinDelayBeforeNewBCEAssign amount of time,entry matches thelocal mobility anchor upon acceptingsource address of the requestMUST assign a new home network prefix and create a new Binding Cache entry. The local mobility anchor MAY also choose to assign a new home network prefix(or the address in the alternate Care-of Address option, if the option is present) andwithout waiting for a de-registration message. It can useif the access technology typevaluefield in the Access Technology Type option present in the requestand as inputs for this decision. 6. Either upon creating a new Binding Cache entry or from matching an existing Binding Cache entry, after applying the above considerations,matches the access technologyfield in the Binding Cache entry MUST be copied from the Access Technologytypeoption present in the received Proxy Binding Update message. The interface identifier fieldin the Binding Cacheentryentry. [BCE(Proxy-CoA, ATT) == PBU(Proxy-CoA, ATT)]. 5. For all other cases, the message MUST beset to ALL_ZERO.considered as a request for creating a new mobility session. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 27] Internet-Draft Proxy Mobile IPv6 February 2008 5.4.1.2. Mobile Node Interface Identifier Option present in therequest:request +=====================================================================+ | Registration/De-Registration Message | +=====================================================================+ | HNP (ALL_ZERO Value) | +=====================================================================+ | ATT | +=====================================================================+ | IID Option Present (NON_ZERO Value) | +=====================================================================+ | HI | +==================================+==================================+ | BCE Lookup Keys: (MN-Identifier + Access Technology Type + | | MN-Interface-Identifier) | +=====================================================================+ Figure 8: BCE Lookup using Interface Identifier 1. The local mobility anchor MUST verify if there is an existing Binding Cacheentry forentry, with the mobilenode, identified bynode identifier matching theMN-identifier in the received Mobile Node Identifier option, access technology type matching the value in the received Access Technology Type option andwiththe interface identifier value matching the identifiervalue presentin the received Mobile Node Interface IdentifierOption.option. [BCE(MN-Identifier, ATT, MN-Interface- Identifier) == PBU(MN-Identifier, ATT, MN-Interface-Identifier)] 2. If there exists a Binding Cacheentry, the local mobility anchor upon accepting the request MUST update the existing Binding Cacheentry (matching MN-Identifier, ATT andassign the home network prefix present inMN-Interface-Identifier), the request MUST be considered as a request for updating that Binding Cache entry. 3. If there does not exist a Binding Cache entry (matching MN- Identifier, ATT and MN-Interface-Identifier) andifthe Handoff Indicator field in theAccess Technology TypeHandoff Indicator option present in thereceived Proxy Binding Update messagerequest is set tovalue 1 (Attachment overanew interface),value of 2 (Handoff between two different interfaces of the mobile node). The local mobility anchorupon Gundavelli, et al. Expires June 27, 2008 [Page 26] Internet-Draft Proxy Mobile IPv6 December 2007 acceptingMUST apply therequestfollowing additional considerations. [PBU(HI) == 2] * The local mobility anchor MUSTassign a new home network prefixverify if there exists one andcreate a new Binding Cache entry. 4. If there does not exist aonly one Binding Cache entryand ifwith theHandoff Indicator fieldmobile node identifier matching the identifier in theAccess Technology TypeMobile Node Identifier option present in thereceived Proxy Binding Update message is set to value 2 (Handoff between interfaces), the local mobility anchor MUST verify if there exists onerequest andonly one Binding Cache entryforthe mobile node, identified by the MN-Identifier and withany interface identifier value. If there exists only one suchan entry,entry (matching thelocal mobility anchor upon acceptingMN- Gundavelli (Editor), et al. Expires August 6, 2008 [Page 28] Internet-Draft Proxy Mobile IPv6 February 2008 Identifier), the request MUSTupdate the existing Binding Cache entry and assign the home network prefix present in thebe considered as a request for updating that Binding Cache entry.5.[BCE(MN-Identifier) == PBU(MN-Identifier)] 4. If there does not exist a Binding Cache entry (matching MN- Identifier, ATT and MN-Interface-Identifier) and if the Handoff Indicator field in theAccess Technology TypeHandoff Indicator option present in thereceived Proxy Binding Update messagerequest is set to a value2of 4 (Handoffbetween interfaces),state unknown), the local mobility anchor MUST apply the following additional considerations. * The local mobility anchor MUST verify if there existsaone and only one Binding Cache entryfor the mobile node, identified by the MN-Identifier andwith thehome network prefix valuemobile node identifier matching theprefix valueidentifier in thereceived Home Network Prefix option. If there exists a Binding Cache entry, the local mobility anchor upon acceptingMobile Node Identifier option present in the requestMUST assign the same prefix, else it MUST assign a new home network prefixandcreate a new Binding Cache entry. 6.for any interface identifier value. If there existsa Binding Cacheonly one such entryand if(matching theHandoff Indicator field in the Access Technology Type option present in the received Proxy Binding Update message is set to value 4 (Handoff state unknown),MN- Identifier), the local mobility anchor SHOULD wait till the existing Binding Cache entry is de-registered by the previously serving mobile accessgateway. However, if there is nogateway, before the request can be considered as a request for updating that Binding Cache entry. However, if there is no de-registration message that is received withina givenMaxDelayBeforeNewBCEAssign amount of time, the local mobility anchor upon accepting the request MUSTassign a new home network prefix and createconsider the request as anewrequest for updating that Binding Cache entry. The local mobility anchor MAY also choose toassigncreate a newhome network prefixmobility session and without waiting for ade-registrationde- registration message.7. Either upon creating a new Binding Cache entry or from matching an existing Binding Cache entry, after applying the above considerations, the interface identifier field in5. For all other cases, theBinding Cache entrymessage MUST beset to the value present in the receivedconsidered as a request for creating a new mobility session. 5.4.1.3. Mobile Node Interface Identifier Optionand the access technology type MUST be copied from the Access Technology type optionnot present in thereceived Proxy Binding Update message. Gundavelli,request Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page27]29] Internet-Draft Proxy Mobile IPv6December 2007 5.5. Timestamp Option forFebruary 2008 +=====================================================================+ | Registration/De-Registration MessageOrdering| +=====================================================================+ | HNP (ALL_ZERO Value) | +=====================================================================+ | ATT | +=====================================================================+ | IID Option Not Present | +=====================================================================+ | HI | +==================================+==================================+ | BCE Lookup Key: (MN-Identifier) | +=====================================================================+ Figure 9: BCE Lookup using MobileIPv6 [RFC-3775] uses the Sequence Number field in binding registration messages as a way for the home agent to process the binding updates in the order they were sent by a mobile node.Node Identifier 1. Thehome agentlocal mobility anchor MUST verify if there exists one and only one Binding Cache entry with the mobile nodeare required to manage this counter overidentifier matching thelifetime of a binding. However,identifier inProxythe MobileIPv6, asNode Identifier option present in themobile node moves fromrequest. 2. If there exists only onemobile access gateway to anothersuch entry (matching the MN-Identifier) andintheabsenceHandoff Indicator field in the Handoff Indicator option present in the request is set to a value ofmechanisms such as context transfer2 (Handoff between two different interfaces of the mobileaccess gateways,node), theserving mobile access gateway willrequest MUST beunable to determine the sequence numberconsidered as a request for updating thatit needs to use inBinding Cache entry. [PBU(HI) == 2] 3. If there exists only one such entry (matching thesignaling messages. Hence,MN-Identifier) and thesequence number scheme, as specifiedHandoff Indicator field in[RFC-3775], will be insufficient for Proxy Mobile IPv6. Ifthe Handoff Indicator option present in the request is set to a value of 4 (Handoff state unknown), the local mobility anchorcannot determine the sending order ofSHOULD wait till thereceived binding registration messages, it may potentially process an older message sentexisting Binding Cache entry is de-registered byathe previously serving mobile accessgateway wheregateway, before themobile node was previously anchored, resulting in an incorrectrequest can be considered as a request for updating that Binding Cache entry.For solving this problem, this specification adopts two alternative solutions. One is based on timestamps and the other based on sequence numbers, as defined in [RFC-3775]. The basic principle behind the use of timestamps in binding registration messagesHowever, if there isthat the node generating theno de-registration messageinsertsthat is received within MaxDelayBeforeNewBCEAssign amount of time, thecurrent time-of-day, andlocal mobility anchor upon accepting thenode receivingrequest MUST consider themessage checksrequest as a request for updating thatthis timestamp is greater than all previously accepted timestamps.Binding Cache entry. Thetimestamp based solution may be used, when the serving mobile access gateways in a Proxy Mobile IPv6 domain do not have the abilitylocal mobility anchor MAY also choose toobtain the last sequence number that was sent increate abinding registration messagenew mobility session and without waiting forupdatingagiven mobile node's binding. As an alternative to the Timestamp based approach, the specification also allowsde-registration message. 4. For all other cases, theuse of Sequence Number based scheme,message MUST be considered asper [RFC- 3775]. However,a request forthis scheme to work, the serving mobile access gateways increating a new mobility session. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 30] Internet-Draft Proxy Mobile IPv6domain MUST have the ability to obtainFebruary 2008 5.5. Timestamp Option for Message Ordering Mobile IPv6 [RFC-3775] uses thelast sequence number that was sentSequence Number field inabinding registrationmessagemessages as a way forupdatingthe home agent to process the binding updates in the order they were sent by agivenmobilenode's binding.node. Thesequence number MUST be maintained onhome agent and the mobile node are required to manage this counter over the lifetime of aperbinding. However, in Proxy Mobile IPv6, as the mobile nodebasismoves from one mobile access gateway to another andMUST be synchronizedin the absence of mechanisms such as context transfer between the mobile access gateways, the serving mobile accessgateways. This maygateway will beachieved by using context transfer schemes or by maintainingunable to determine the sequence number that it needs to use ina policy store. However,thespecific details on howsignaling messages. Hence, themobile node'ssequence numberis synchronized between different mobile access gateways is outside the scope of this document. Gundavelli, et al. Expires June 27, 2008 [Page 28] Internet-Draftscheme, as specified in [RFC-3775], will be insufficient for Proxy MobileIPv6 December 2007 Using Timestamps based approach: 1. AIPv6. If the local mobility anchorimplementation MUST support Timestamp option. Ifcannot determine theTimestamp option is present insending order of the receivedProxybinding registration messages, it may potentially process an older message sent by a mobile access gateway where the mobile node was previously anchored, resulting in an incorrect BindingUpdate request message, thenCache entry. For solving this problem, this specification adopts two alternative solutions. One is based on timestamps and thelocal mobility anchor MUST include a valid Timestamp optionother based on sequence numbers, as defined in [RFC-3775]. The basic principle behind the use of timestamps in binding registration messages is that the node generating the message inserts the current time-of-day, and the node receiving theProxy Binding Acknowledgementmessage checks thatit sends tothis timestamp is greater than all previously accepted timestamps. The timestamp based solution may be used, when the serving mobile accessgateway. 2. All the mobility entitiesgateways in a Proxy Mobile IPv6 domain do not have the ability to obtain the last sequence number thatare exchangingwas sent in a binding registrationmessages usingmessage for updating a given mobile node's binding. As an alternative to the Timestampoption must have adequately synchronized time-of-day clocks. This isbased approach, theessential requirementspecification also allows the use of Sequence Number based scheme, as per [RFC- 3775]. However, for thissolutionscheme towork. If this requirement is not met,work, thesolution will not predictably workserving mobile access gateways in a Proxy Mobile IPv6 domain MUST have the ability to obtain the last sequence number that was sent in a binding registration message for updating a given mobile node's binding. The sequence number MUST be maintained on a per mobile node basis and MUST be synchronized between the serving mobile access gateways. This may be achieved by using context transfer schemes or by maintaining the sequence number in a policy store. However, the specific details on how the mobile node's sequence number is synchronized between different mobile access gateways is outside the scope of this document. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 31] Internet-Draft Proxy Mobile IPv6 February 2008 Using Timestamps based approach: 1. A local mobility anchor implementation MUST support Timestamp option. If the Timestamp option is present in the received Proxy Binding Update request message, then the local mobility anchor MUST include a valid Timestamp option in the Proxy Binding Acknowledgement message that it sends to the mobile access gateway. 2. All the mobility entities in a Proxy Mobile IPv6 domain that are exchanging binding registration messages using the Timestamp option must have adequately synchronized time-of-day clocks. This is the essential requirement for this solution to work. If this requirement is not met, the solution will not predictably work in all cases. 3. The mobility entities in a Proxy Mobile IPv6 domain SHOULD synchronize their clocks to a common time source. For synchronizing the clocks, the nodes may use Network Time Protocol [RFC-4330]. Deployments may also adopt other approaches suitable for that specific deployment. Alternatively, if there is mobile node generated timestamp that is increasing at every attachment to the access link and if that timestamp is available to the mobile access gateway (Ex: The timestamp option in the SEND messages that the mobile node sends), the mobile access gateway can use this timestamp or sequence number in the Proxy Binding Update messages and does not have to depend on any external clock source. However, the specific details on how this is achieved is outside the scope of this document. 4. When generating the timestamp value for building the Timestamp option, the mobility entities MUST ensure that the generated timestamp is the elapsed time past the same reference epoch, as specified in the format for the Timestamp option [Section8.7].8.8]. 5. If the Timestamp option is present in the received Proxy Binding Update message, the local mobility anchor MUST ignore the sequence number field in the message. However, it MUST copy the sequence number from the received Proxy Binding Update message to the Proxy Binding Acknowledgement message. 6. Upon receipt of a Proxy Binding Update message with the Timestamp option, the local mobility anchor MUST check the timestamp field for validity. In order for it to be considered valid, the timestamp value contained in the Timestamp option MUST be close enough (within TimestampValidityWindow amount of time difference) to the local mobility anchor's time-of-day clock and the timestamp MUST be greater than all previously accepted timestamps Gundavelli (Editor), et al. Expires August 6, 2008 [Page 32] Internet-Draft Proxy Mobile IPv6 February 2008 in the Proxy Binding Update messages sent for that mobile node.Gundavelli, et al. Expires June 27, 2008 [Page 29] Internet-Draft Proxy Mobile IPv6 December 20077. If the timestamp value in the received Proxy Binding Update is valid (validity as specified in the above considerations), the local mobility anchor MUST return the same timestamp value in the Timestamp option included in the Proxy Binding Acknowledgement message that it sends to the mobile access gateway. 8. If the timestamp value in the received Proxy Binding Update is lower than the previously accepted timestamp in the Proxy Binding Update messages sent for that mobility binding, the local mobility anchor MUST reject the Proxy Binding Update request and send a Proxy Binding Acknowledgement message with Status field set to TIMESTAMP_LOWER_THAN_PREV_ACCEPTED (Timestamp lower than previously accepted timestamp). The message MUST also include the Timestamp option with the value set to the current time-of- day on the local mobility anchor. 9. If the timestamp value in the received Proxy Binding Update is not valid (validity as specified in the above considerations), the local mobility anchor MUST reject the Proxy Binding Update and send a Proxy Binding Acknowledgement message with Status field set to TIMESTAMP_MISMATCH (Timestamp mismatch). The message MUST also include the Timestamp option with the value set to the current time-of-day on the local mobility anchor. Using Sequence Number based approach: 1. If the Timestamp option is not present in the received Proxy Binding Update request, the local mobility anchor MUST fallback to the Sequence Number based scheme. It MUST process the sequence number field as specified in [RFC-3775]. Also, it MUST NOT include the Timestamp option in the Proxy Binding Acknowledgement messages that it sends to the mobile access gateway. 2. An implementation MUST support Sequence Number based scheme, as per [RFC-3775]. 5.6. Routing Considerations 5.6.1. Bi-Directional Tunnel Management o A bi-directional tunnel MUST be established between the local mobility anchor and the mobile access gateway with IP-in-IP encapsulation, as described in [RFC-2473]. The tunnel end points Gundavelli (Editor), et al. Expires August 6, 2008 [Page 33] Internet-Draft Proxy Mobile IPv6 February 2008 are the Proxy-CoA and LMAA. When using IPv4 transport with a specific encapsulation mode, the end points of the tunnel are theGundavelli, et al. Expires June 27, 2008 [Page 30] Internet-Draft Proxy Mobile IPv6 December 2007IPv4-LMAA and IPv4-Proxy-CoA, as specified in [ID-IPV4-PMIP6]. o The bi-directional tunnel MUST be used for routing the mobile node's data traffic between the mobile access gateway and the local mobility anchor. The tunnel hides the topology and enables a mobile node to use an address from its home network prefix from any access link attached to the mobile access gateway. o The bi-directional tunnel is established after accepting the Proxy Binding Update request message. The created tunnel may be shared with other mobile nodes attached to the same mobile access gateway and with the local mobility anchor having a Binding Cache entry for those mobile nodes. Implementations MAY choose to use static tunnels instead of dynamically creating and tearing them down on a need basis. o Implementations MAY use a software timer for managing the tunnel lifetime and a counter for keeping a count of all the mobile nodes that are sharing the tunnel. The timer value MUST be set to the accepted binding lifetime and will be updated after each periodic re-registration for extending the lifetime. If the tunnel is shared for multiple mobile nodes, the tunnel lifetime MUST be set to the highest binding lifetime that is granted to any one of those mobile nodes sharing that tunnel. 5.6.2. Forwarding Considerations Intercepting Packets Sent to the Mobile Node's Home Network: o When the local mobility anchor is serving a mobile node, it MUST be able to receive packets that are sent to the mobile node's home network. In order for it to receive those packets, it MUST advertise a connected route in to the Routing Infrastructure for the mobile node's home network prefix or for an aggregated prefix with a larger scope. This essentially enables IPv6 routers in that network to detect the local mobility anchor as the last-hop router for that prefix. Forwarding Packets to the Mobile Node: o On receiving a packet from a correspondent node with the destination address matching a mobile node's home network prefix, the local mobility anchor MUST forward the packet through the bi- directional tunnel setup for that mobile node. The format of the tunneled packet is shown below. However, when using IPv4 Gundavelli (Editor), et al. Expires August 6, 2008 [Page 34] Internet-Draft Proxy Mobile IPv6 February 2008 transport, the format of the packet is as described in [ID-IPV4- PMIP6].Gundavelli, et al. Expires June 27, 2008 [Page 31] Internet-Draft Proxy Mobile IPv6 December 2007IPv6 header (src= LMAA, dst= Proxy-CoA /* Tunnel Header */ IPv6 header (src= CN, dst= MN-HOA ) /* Packet Header */ Upper layer protocols /* Packet Content*/ Figure7:10: Tunneled Packets from LMA to MAG Forwarding Packets Sent by the Mobile Node: o All the reverse tunneled packets that the local mobility anchor receives from the mobile access gateway, after removing the tunnel header MUST be routed to the destination specified in the inner packet header. These routed packets will have the source address field set to the mobile node's home address. 5.7. Local Mobility Anchor Address Discovery Dynamic Home Agent Address Discovery, as explained in Section 10.5 [RFC-3775], allows a mobile node to discover all the home agents on its home link by sending an ICMP Home Agent Address Discovery Request message to the Mobile IPv6 Home-Agents anycast address, derived from its home network prefix. The DHAAD message in the current form cannot be used in Proxy Mobile IPv6 for discovering the address of the mobile node's local mobility anchor. In Proxy Mobile IPv6, the local mobility anchor will not be able to receive any messages sent to the Mobile IPv6 Home-Agents anycast address corresponding to the mobile node's home network prefix, as the prefix is not hosted on any of its interfaces. Further, the mobile access gateway will not predictably be able to locate the serving local mobility anchor that has the mobile node's binding cache entry. Hence, this specification does not support Dynamic Home Agent Address Discovery protocol. In Proxy Mobile IPv6, the address of the local mobility anchor configured to serve a mobile node can be discovered by the mobility entities in other ways. This may be a configured entry in the mobile node's policy profile, or it may be obtained through mechanisms outside the scope of this document.5.8. Mobile Prefix Discovery Considerations The ICMP Mobile Prefix Advertisement message, described in Section 6.8 and Section 11.4.3 of [RFC-3775], allows a home agent to send a Mobile Prefix Advertisement to the mobile node. Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page32]35] Internet-Draft Proxy Mobile IPv6December 2007 In ProxyFebruary 2008 5.8. MobileIPv6, thePrefix Discovery Considerations This specification does not support mobilenode's home networkprefixis hosted on the access link connected to the mobile access gateway, but it is topologically anchored on the local mobility anchor. Since there is no physical home-link for thediscovery. The mobilenode's home networkprefixon the local mobility anchor anddiscovery mechanism asthe mobile node is always on the link where the prefix is hosted, any prefix change messages can just be advertised by the mobile access gateway on the access link and thus therespecified in [RFC-3775] isno applicability of this message fornot applicable to Proxy Mobile IPv6.Hence, this specification does not support Mobile Prefix Discovery.5.9. Route Optimizations Considerations The Route Optimization in Mobile IPv6, as defined in [RFC-3775], enables a mobile node to communicate with a correspondent node directly using its care-of address and further the Return Routability procedure enables the correspondent node to have reasonable trust that the mobile node is reachable at both its home address and care-of address. In Proxy Mobile IPv6, the mobile node is not involved in any IP mobility related signaling. The mobile node uses only its home address for all its communication and the Care-of address (Proxy-CoA) is not visible to the mobile node. Hence, the Return Routability procedure as defined in Mobile IPv6 [RFC-3775] cannot be used in Proxy Mobile IPv6. 6. Mobile Access Gateway Operation The Proxy Mobile IPv6 protocol described in this document introduces a new functional entity, the Mobile Access Gateway (MAG). The mobile access gateway is the entity that is responsible for detecting the mobile node's movementson itsto and from the access link and sending the binding registration requests to the local mobility anchor. In essence, the mobile access gateway performs mobility management on behalf of a mobile node. The mobile access gateway is a function that typically runs on an access router. However, implementations MAY choose to split this function and run it across multiple systems. The specifics on how that is achieved or the signaling interactions between those functional entities are beyond the scope of this document. The mobile access gateway has the following key functional roles: o It is responsible for detecting the mobile node's movements on the access link and for initiating the mobility signaling with the mobile node's local mobility anchor.Gundavelli, et al. Expires June 27, 2008 [Page 33] Internet-Draft Proxy Mobile IPv6 December 2007o Emulation of the mobile node's home link on the access link by sending Router Advertisements with the mobile node's home network prefix information. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 36] Internet-Draft Proxy Mobile IPv6 February 2008 o Responsible for setting up the data path for enabling the mobile node to configure an address from its home network prefix and use it from its access link. 6.1. Extensions to Binding Update List Entry Data Structure Every mobile access gateway MUST maintain a Binding Update List. Each entry in the Binding Update List represents a mobile node's mobility binding with its local mobility anchor. The Binding Update List is a conceptual data structure, described in Section 11.1 [RFC- 3775]. For supporting this specification, the conceptual Binding Update List entry data structure needs be extended with the following additional fields. o The Identifier of the attached mobile node, MN-Identifier. This identifier is acquired during the mobile node's attachment to the access link through mechanisms outside the scope of this document. o The interface identifier of the mobile node's connected interface. This address can be acquired from the received Router Solicitation messages from the mobile node or during the mobile node's attachment to the access network. This is typically a Layer-2 identifier conveyed by the mobile node; however, the specific details on how that is conveyed is out of scope for this specification. If this identifier is not available, the value MUST be set to ALL_ZERO. o The IPv6 home network prefix of the attached mobile node. The home network prefix of the mobile node is acquired from the mobile node's local mobility anchor through the received Proxy Binding Acknowledgement messages. The IPv6 home network prefix also includes the corresponding prefix length. o The Link-local address of the mobile node on the interface attached to the access link. o The IPv6 address of the local mobility anchor serving the attached mobile node. This address is acquired from the mobile node's policy profile or from other means. o TheInterfaceinterface identifier (If-Id) of the access link where the mobile node is currently attached. This is internal to the mobileGundavelli, et al. Expires June 27, 2008 [Page 34] Internet-Draft Proxy Mobile IPv6 December 2007access gateway and is used to associate the Proxy Mobile IPv6 tunnel to therightaccess link where the mobile node is attached.o The interface identifier (If-Id) of the bi-directional tunnelGundavelli (Editor), et al. Expires August 6, 2008 [Page 37] Internet-Draft Proxy Mobile IPv6 February 2008 o The interface identifier (If-Id) of the bi-directional tunnel between the mobile node's local mobility anchor and the mobile access gateway. This is internal to the mobile access gateway. The tunnel interface identifier is acquired during the tunnel creation. 6.2. Mobile Node's Policy Profile A mobile node's policy profile contains the essential operational parameters that are required by the network entities for managing the mobile node's mobility service. These policy profiles are stored in a local or a remote policy store. The mobile access gateway and the local mobility anchor MUST be able to obtain a mobile node's policy profile. The policy profile MAY also be handed over to a serving mobile access gateway as part of a context transfer procedure during a handoff or the serving mobile access gateway MAY be able to dynamically generate this profile. The exact details on how this achieved is outside the scope of this document. However, this specification requires that a mobile access gateway serving a mobile node MUST have access to its policy profile. The following are the mandatory fields of the policy profile: o The mobile node's identifier (MN-Identifier) o The IPv6 address of the local mobility anchor (LMAA) The following are the optional fields of the policy profile: o The mobile node's IPv6 home network prefix (MN-HNP) o The mobile node's IPv6 home network Prefix lifetime o Supported address configuration procedures (Stateful, Stateless or both)onfor theaccess linksmobile node in the Proxy Mobile IPv6 domain 6.3. Supported Access Link Types This specification supports only point-to-point access link types and thus it assumes that the mobile node and the mobile access gateway are the only two nodes on the access link. The link is assumed to have multicast capability. This protocol may also be used on other link types, as long as the link is configured in such a way that it guarantees a point-to-point delivery between the mobile node and the mobile access gateway for all the protocol traffic.Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page35]38] Internet-Draft Proxy Mobile IPv6December 2007February 2008 6.4. Supported Address ConfigurationModelsModes A mobile node in the Proxy Mobile IPv6 domain can configure one or more IPv6 addresses on its interface using Stateless or Stateful address autoconfiguration procedures. The Router Advertisement messages sent on the access link specify the address configuration methods permitted on that access link for that mobile node. However, the advertised flags with respect to the address configuration will be consistent for a mobile node, on any of the access links in that Proxy Mobile IPv6 domain. Typically, these configuration settings will be based on the domain wide policy or based on a policy specific to each mobile node. When stateless address autoconfiguration is supported on the access link, the mobile node can generate one or more IPv6 addresses bycombining the network prefix advertised on the access link with an interface identifier, using the techniques described instandard IPv6 mechanisms such as Stateless Autoconfiguration specification [RFC-4862] oras perPrivacy extension specification[RFC-4941].[RFC- 4941]. When stateful address autoconfiguration is supported on the link, the mobile node can obtain the address configuration from the DHCPv6 serverusingby standard DHCPv6client protocol,mechanisms, as specified in DHCPv6 specification [RFC-3315]. Additionally, other address configuration mechanisms specific to the access link between the mobile node and the mobile access gateway may also be used for pushing the address configuration to the mobile node. This specification does not change the behavior of address configuration mechanisms in any way. 6.5. Access Authentication & Mobile Node Identification When a mobile node attaches to an access link connected to the mobile access gateway, the deployed access security protocols on that link SHOULD ensure that the network-based mobility management service is offered only after authenticating and authorizing the mobile node for that service. The exact specifics on how this is achieved or the interactions between the mobile access gateway and the access security service is outside the scope of this document. This specification goes with the stated assumption of having an established trust between the mobile node and the mobile access gateway, before the protocol operation begins. 6.6. Acquiring Mobile Node's Identifier All the network entities in a Proxy Mobile IPv6 domain MUST be able to identify a mobile node, using its MN-Identifier. This identifier MUST be stable across the Proxy Mobile IPv6 domain and the entitiesGundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page36]39] Internet-Draft Proxy Mobile IPv6December 2007February 2008 must be able to use this identifier in the signaling messages. Typically, this identifier is obtained as part of the access authentication or through other means as specified below. o The identifier of the mobile node that the mobile access gateway obtains typically as part of the access authentication or from the notified network attachment event, can be a temporary identifier andthisfurther that temporary identifier mayalso changebe different at eachre-authentication. However, there- authentication. The mobile access gateway MUST be able to use this temporary identifier and obtain the mobile node'sMN-Identifierstable identifier from the policystore, such as fromstore. For instance, in AAA-based systems the RADIUS attribute,Chargeable-User- Identifier [RFC-4372].Chargeable-User-Identifier [RFC- 4372] may be used. o The MN-Identifier that the policy store delivers to the mobile access gateway may not be the true identifier of the mobile node. However, the mobility access gateway MUST be able to use this identifier in the signaling messages exchanged with the local mobility anchor. o The mobile access gateway MUST be able to identify the mobile node by its MN-Identifier and it MUST be able to associate this identity to thesender of any IPv4 or IPv6 packets onpoint-to-point link sharing with theaccess link.mobile node. 6.7. Home Network Emulation One of the key functions of a mobile access gateway is to emulate the mobile node's home network on the access link. It must ensure, the mobile node believes it is still connected to its home link or on the link where it obtained its initial address configuration after it moved into that Proxy Mobile IPv6 domain. For emulating the mobile node's home link on the access link, the mobile access gateway must be able to send Router Advertisements advertising the mobile node's home network prefix and other address configuration parameters consistent with its home link properties. Typically, these configuration settings will be based on the domain wide policy or based on a policy specific to each mobile node. Typically, the mobile access gateway learns the mobile node's home network prefix information from the received Proxy Binding Acknowledgement message or it may be obtained from the mobile node's policy profile. However, the mobile access gateway SHOULD send the Router Advertisements advertising the mobile node's home network prefix only after successfully completing the binding registration with the mobile node's local mobility anchor. When advertising the home network prefix in the Router Advertisement Gundavelli (Editor), et al. Expires August 6, 2008 [Page 40] Internet-Draft Proxy Mobile IPv6 February 2008 messages, the mobile access gateway MAY set the prefix lifetime valueGundavelli, et al. Expires June 27, 2008 [Page 37] Internet-Draft Proxy Mobile IPv6 December 2007for the advertised prefix to any chosen value at its own discretion. An implementation MAY choose to tie the prefix lifetime to the mobile node's binding lifetime. The prefix lifetime can also be an optional configuration parameter in the mobile node's policy profile. 6.8. Link-Local and Global Address Uniqueness A mobile node in the Proxy Mobile IPv6 domain, as it moves from one mobile access gateway to the other, will continue to detect its home network and thus making it believe it is still on the same link. Every time the mobile node attaches to a new link, the event related to the interface state change will trigger the mobile node to perform DAD operation on the link-local and global addresses. However, if the mobile node is DNAv6 enabled, as specified in [ID-DNAV6], it may not detect the link change due to DNAv6 optimizations and may not trigger the duplicate address detection (DAD) procedure for establishing the link-local address uniqueness on that new link.Further, if the mobile node uses an interface identifier that is not based on EUI-64 identifier, such as specified in IPv6 Stateless Autoconfiguration specification [RFC-4862], there is a very low possibility ofThis leaves a room for link-local address collision between the two neighbors on that access link. For solving this problem, this specification allows the mobile access gateway to upload the mobile node's link-local address to the local mobility anchor using the Link-local Address option, exchanged in the binding registration messages. The mobile access gateway can learn the mobile node's link-local address, by snooping the DAD messages sent by the mobile node for establishing the link-local address uniqueness on the access link. Subsequently, at each handoff, the mobile access gateway can obtain this address from the local mobility anchor to ensure link-local address uniqueness and change its own link-local address, if it detects a collision. Alternatively, one of the workarounds for this issue is to set the DNAv6 configuration parameter, DNASameLinkDADFlag to TRUE and that will force the mobile node to redo DAD operation on the global and link-local addresses every time the interface detectsa handover,an handoff, even when DNAv6 does not detect a link change. However, this issuewillmay not impact point-to-point links based ona PPP session.PPP. Each time the mobile node moves and attaches to a new mobile access gateway,eitherthe PPP session [RFC-1661]is reestablishedcan be re-established, or if there are context transfer procedures in place, the entire PPP sessionmaycan be movedas part of context transfer procedures betweento theoldnew link and thenew mobile access gateway. Whenlink-local addresses of both themobile node triespeers will continue toestablish a PPP session withremain themobile Gundavelli, et al. Expires June 27, 2008 [Page 38] Internet-Draft Proxy Mobile IPv6 December 2007 access gateway, the PPP goes through the Network layer Protocol phase and the IPv6 Control Protocol, IPV6CP [RFC-5072] gets triggered. Both the PPP peers negotiate a unique identifier using Interface- Identifier option in IPV6CP andsame. In either of these approaches, thenegotiated identifier is used for generating a uniquelink-local address uniqueness onthat link. Now, ifthemobile node moves to a new mobile access gateway, the PPP session gets torn down withlink is assured. The specific details of how theold mobile access gateway and a newPPP sessiongets established with the new mobile access gateway, and the mobile node obtains a new link-local address. So, even if the mobile nodeisDNAv6 capable, the mobile node always configures a new link- local address whenever it moves to a new link. Ifre-established without impacting any layer-3 sessions or how the PPP sessionstate iscan be movedtobetween thenewmobile accessgateway as part of context transfer procedures that are in place, there will not be any change to the interface identifiers of the two nodes on that point-to-point change. The whole linkgateways ismoved tooutside thenew mobile access gateway and there will not be any need for establishing link- local address uniqueness on that link.scope of this Gundavelli (Editor), et al. Expires August 6, 2008 [Page 41] Internet-Draft Proxy Mobile IPv6 February 2008 document. The issue of address collision is not relevant to the mobile node's global address. Since there is a unique home network prefix assigned for each mobile node, the uniqueness for the mobile node's global address is assured on the access link. 6.9. Signaling Considerations 6.9.1. Binding Registrations 6.9.1.1. Mobile Node Attachment and Initial BindingRegistration:Registration 1. After detecting a new mobile node on its access link, the mobile access gatewaymustMUST identify the mobile node and acquire its MN- Identifier. If it determines that the network-based mobility management service needs to be offered to the mobile node, it MUST send a Proxy Binding Update message to the local mobility anchor.If there is no existing Binding Update List entry for that mobile node, the mobile access gateway MUST create a Binding Update List entry upon sending the Proxy Binding Update request.2. The Proxy Binding Update message MUST include the Mobile Node Identifier option [RFC-4283], carrying the MN-Identifier for identifying the mobilenode, thenode. 3. The Home Network Prefixoption, either the Timestampoptionor a valid sequence number and optionally the Link-local Address option. When Timestamp option is added toMUST be present in themessage,Proxy Binding Update message. If the mobile access gatewayMAY setlearns theSequence Number field to a value of a monotonically increasing counter andmobile node's home network prefix either from its policy store or from other means, thelocal mobility anchor will ignore this field, but will returnmobile access gateway MAY choose to specify the sameGundavelli, et al. Expires June 27, 2008 [Page 39] Internet-Draft Proxy Mobile IPv6 December 2007 valuein theProxy Binding Acknowledgement message. This will be usefulHome Network Prefix option formatchingrequesting thereplylocal mobility anchor tothe request message. 3. The Home Address optionallocate that prefix, otherwise it MUSTNOT be present in the Destination Option extension headerspecify a value of ALL_ZERO. If theProxy Binding Update message.specified value is ALL_ZERO, then the local mobility anchor will do the prefix assignment. 4. TheAccess Technology TypeHandoff Indicator option MUST be present in the Proxy Binding Update message. Theaccess technology Type field in the option MUST be set to the access technology using which the mobile node is currently attached to the mobile access gateway. TheHandoff Indicator field in theAccess Technology TypeHandoff Indicator option MUST be set to a value indicating theappropriate value.handoff hint. The specific details on how the mobile access gatewayis able to determinedetermines if the mobile node's current attachment is due toaan handoff of an existing mobility session or if it is as a result of an attachment over a different interface is outside the scope of this document.5.* The Handoff Indicator fieldin the Access Technology Type optionMUST be set to value 1 (Attachment over a new interface), if the mobile access gateway predictably knows that the mobile node's current attachment to the networkusing the currentover this interface isdue to neithernot as ahandover between two interfacesresult ofthe mobile node nor a handoveran handoff ofthean existing mobility sessionfor(over Gundavelli (Editor), et al. Expires August 6, 2008 [Page 42] Internet-Draft Proxy Mobile IPv6 February 2008 the same interface or through a different interface), but as a result ofthe mobile node between two mobile access gateways.an attachment over a new interface. This essentially serves as a request to the local mobility anchor toallocatecreate a newhome network prefix for thismobility session and not update any existing Binding Cache entry created for the same mobile node connected to the Proxy Mobile IPv6 domain through a different interface.6.* The Handoff Indicator fieldin the Access Technology Type optionMUST be set to value 2 (Handoff betweeninterfaces),two different interfaces of the mobile node), if the mobile access gateway definitively knows the mobile node's current attachment is due toaan handoff ofthean existing mobilitysessionsession, between two different interfaces of the mobile node.7.* The Handoff Indicator fieldin the Access Technology Type optionMUST be set to value 3 (Handoff between mobile access gateways for the same interface), if the mobile access gateway definitively knows the mobile node's current attachment is due toaan handoff ofthean existing mobility session betweendifferenttwo mobile access gateways and for the same interface of the mobile node.8.* The Handoff Indicator fieldin the Access Technology Type optionMUST be set to value 4 (HandoffState Unknown),state unknown), if the mobile access gateway cannotpredictably knowdetermine if the mobile node'ssessioncurrent attachment is due to an handoff of an existing mobility session. 5. Either the Timestamp option or a valid sequence number maintained on a per mobile node basis (if Sequence Number based scheme is in use) MUST be present. When Timestamp option is added to the message, the mobile access gateway SHOULD also set the Sequence Number field to ahandoff. Gundavelli, et al. Expires June 27, 2008 [Page 40] Internet-Draftvalue of a monotonically increasing counter (not to be confused with the per mobile node sequence number specified [RFC-3775]). The local mobility anchor will ignore this field when there is a Timestamp option present in the request, but will return the same value in the ProxyMobile IPv6 December 2007 9.Binding Acknowledgement message. This will be useful for matching the reply to the request message. 6. The Mobile Node Interface Identifier option carrying the interface identifier of the currently attached interface MUST be present in the Proxy Binding Update message, if the mobile access gateway knows the interface identifier of the mobile node's currently attached interface.The "P" Flag in the option MUST be set to 0, indicating that the carried identifier is the currently attached interface identifier.If the interface identifier is notknown, thisknown or if the identifier value is ALL_ZERO, this option MUST NOT be present.10. IfGundavelli (Editor), et al. Expires August 6, 2008 [Page 43] Internet-Draft Proxy Mobile IPv6 February 2008 7. The Access Technology Type option MUST be present in themobileProxy Binding Update message. The accessgateway learnstechnology type field in themobile node's home network prefix either from its policy store or from other means,option SHOULD be set to the type of access technology using which the mobile node is currently attached to the mobile accessgatewaygateway. 8. The Link-local Address option MAYchoosebe present in the Proxy Binding Update message. Considerations from Section 6.8 MUST be applied when using the link-local address option. * When uploading the link-local address tospecifythesamelocal mobility anchor, the value in theHome Network Prefixoptionfor requestingMUST be set to the link-local address that is configured on the currently attached interface of the mobile node. * When querying the local mobility anchorto allocate that prefix. Iffor thespecified value is 0::/0, thenmobile node's link-local address, the option MUST be set to ALL_ZERO value. This essentially serves as a request to the local mobility anchorwill considerto return the link-local address of the mobile node from the binding cache entry corresponding to this mobility session. 9. The Proxy Binding Update message MUST be constructed as specified in Section 6.9.1.5. 10. If there is no existing Binding Update List entry for that mobile node, the mobile access gateway MUST create arequestBinding Update List entry forprefix allocation.the mobile node upon sending the Proxy Binding Update request. 6.9.1.2. Receiving Binding RegistrationReply: 1. TheReply On receiving a Proxy Binding Acknowledgement message from the local mobility anchor, the mobile access gateway MUSTobserve the rules described in Section 9.2 [RFC-3775] when processing Mobility Headers inprocess the message as specified below. 1. The received Proxy Binding Acknowledgement message (a Binding Acknowledgement message with the 'P' flagset). 2. The messageset) MUST be authenticated as described in Section 4.0. When IPsec is used for message authentication, the SPI in the IPsec header[RFC-4306][RFC- 4306] of the received packet is needed for locating the security association, for authenticating the Proxy Binding Acknowledgementreply. 3.message . 2. The mobile access gateway MUSTapplyobserve theconsiderations specifiedrules described in Section5.5 for9.2 [RFC-3775] when processing Mobility Headers in theSequence Number field andGundavelli (Editor), et al. Expires August 6, 2008 [Page 44] Internet-Draft Proxy Mobile IPv6 February 2008 received Proxy Binding Acknowledgement message. 3. The mobile access gateway MUST apply the considerations specified in Section 5.5 for processing the Sequence Number field and the Timestampoption,option (if present), in the message. 4. The mobile access gateway MUST ignore any checks, specified in [RFC-3775] related to the presence of Type 2 Routing header in the Proxy Binding Acknowledgement message. 5.If the Timestamp option is present in the received Proxy Binding Acknowledgement message and with the Status field value set to any value other than TIMESTAMP_MISMATCH (Invalid Timestamp), theThe mobile access gateway MAY use thetimestamp valuemobile node identifier present in the Mobile Node Identifier option for matching the response to the requestmessagemessages that it sentrecently. For all other cases, it MAY userecently . However, if there are more than one request message in its request queue for the same mobile node, the sequence numberin combination withfield can be used for identifying theidentifier present inexact message from those messages. There are other ways to achieve this and implementations are free to adopt the best approach that suits their implementation. Additionally, if the received Proxy Binding Acknowledgement message does not match any of the Proxy Binding Update messages that it sent recently, the message MUST be ignored. 6. If the received Proxy Binding Acknowledgement message has any one or more of the following options, Handoff Indicator option, Access Technology Type option, Mobile Node Interface Identifier option, Mobile Node Identifier option, carrying optionfor matchingvalues that are different from theresponseoption values present in the corresponding request (Proxy Binding Update) message, the message MUST be ignored as the local mobility anchor is expected to echo back all these listed options and with therequest. Gundavelli, et al. Expires June 27, 2008 [Page 41] Internet-Draft Proxy Mobile IPv6 December 2007 6.same option values in the reply message. 7. If the received Proxy Binding Acknowledgement message has the Status field value set to PROXY_REG_NOT_ENABLED (Proxy registration not enabled for the mobile node), the mobile access gateway SHOULD NOT send binding registration requests again for that mobile node. Itmust alsoMUST deny the mobility service to that mobile node.7.8. If the received Proxy Binding Acknowledgement message has the Status field value set to TIMESTAMP_LOWER_THAN_PREV_ACCEPTED (Timestamp value lower than previously acceptedtimestamp),value), the mobile access gateway SHOULD try to register again to reassert the mobile node's presenceto the mobility anchor.on its access link. The mobile access gateway is not specifically required to synchronize its clock upon receiving this error code.8.Gundavelli (Editor), et al. Expires August 6, 2008 [Page 45] Internet-Draft Proxy Mobile IPv6 February 2008 9. If the received Proxy Binding Acknowledgement message has the Status field value set to TIMESTAMP_MISMATCH (InvalidTimestamp),timestamp value), the mobile access gateway SHOULD try to register again only after it has synchronized its clock to a common time source that is used by all the mobility entities in that domain for their clock synchronization. The mobile access gateway SHOULD NOT synchronize its clock to the local mobility anchor's system clock, based on the timestamp present in the received message.9.10. If the received Proxy Binding Acknowledgement message has the Status field value set to NOT_AUTHORIZED_FOR_HOME_NETWORK_PREFIX(Not(mobile node is not authorized forthatthe requesting home network prefix), the mobile access gateway SHOULDtry toNOT request forthatthe same prefix again, but can request the local mobility anchor to dynamically assign a prefix, by specifying a ALL_ZERO value in thebinding registration request, only after it learnedHome Network Prefix option carried in thevalidity of that prefix. 10.subsequent Proxy Binding Update message. 11. If the received Proxy Binding Acknowledgement message has the Status field value set to any value greater than or equal to 128 (i.e., if the binding is rejected), the mobile access gateway MUST NOT advertise the mobile node's home network prefix in the Router Advertisements sent on that access link and there by denying mobility service to the mobile node.11.12. If the received Proxy Binding Acknowledgement message has the Status field value set to 0 (Proxy Binding Update accepted), the mobile access gateway MUSTsetupupdate the routing state, as explained in section 6.10, and MUST also update the Binding Update List entry for reflecting the accepted binding registration status.12.13. If the received Proxy Binding Acknowledgement message has the address in the Link-local Address option set to a value that matches its own link-local address on that access interfaceGundavelli, et al. Expires June 27, 2008 [Page 42] Internet-Draft Proxy Mobile IPv6 December 2007where the mobile node is anchored, the mobile access gateway MUST change its link-local address on thatinterface.interface, to avoid link-local address collision on that access link. 6.9.1.3. Extending BindingLifetime:Lifetime 1. For extending the lifetime of a currently registered mobile node (i.e.,if there existsafter aBinding Update List entry for thatsuccessful initial binding registration from the same mobilenode),access gateway), the mobile access gatewayMUSTcan send a Proxy Binding Update message to the local mobilityanchor.anchor with a new lifetime value. This re-registration message MUST be constructed with the same set of options as the initial binding Gundavelli (Editor), et al. Expires August 6, 2008 [Page 46] Internet-Draft Proxy Mobile IPv6 February 2008 registration message, under the considerations specified in Section 6.9.1.1. However the following exceptions apply. 2. The prefix value in the Home Network Prefix optionpresent in the request SHOULDMUST be set to the currentlyregisteredassigned home networkprefix andprefix. 3. The Handoff Indicator field in the Handoff Indicator option MUST be set to a value of 5 (Handoff state not changed - Re- Registration). 4. The value in the Link-local Address optionMAY(if the option was present in the initial registration message) MUST be set toALL_ZERO or tothe link-local address of the mobilenode.node's attached interface. 6.9.1.4. Mobile Node Detachment and BindingDe-Registration:De-Registration 1. At any point,ifthe mobile access gateway detects that the mobile node has moved away from its access link, or if it decides to terminate the mobile node's mobility session, it SHOULD send a Proxy Binding Update message to the local mobility anchor with the lifetime value set to zero.2. Either upon receipt of a Proxy Binding AcknowledgementThis de-registration message MUST be constructed with the same set of options as the initial binding registration message, under the considerations specified in Section 6.9.1.1. However, the following exceptions apply. 2. The prefix value in the Home Network Prefix option MUST be set to the currently assigned home network prefix. 3. The Handoff Indicator field in the Handoff Indicator option MUST be set to a value of 4 (Handoff state unknown). 4. The value in the Link-local Address option (if the option was present in the initial registration message) MUST be set to the link-local address of the mobile node's attached interface. Either upon receipt of a Proxy Binding Acknowledgement message from the local mobility anchor or aftera MinPBUReplyTimeINITIAL_BINDINGACK_TIMEOUT [RFC- 3775] timeout waiting for the reply, the mobile access gateway MUST do the following: 1. It MUST remove the BindingCacheUpdate List entry forthatthe mobile node from its Binding UpdateList andList. 2. It MUST withdraw the mobile node's home network prefix as the hosted on-link prefix, by sending a Router Advertisement message with the prefix lifetime value set to zero. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 47] Internet-Draft Proxy Mobile IPv6 February 2008 3. It MUST remove the created routing state for tunneling the mobile node's traffic. 4. It SHOULD teardown the point-to-point link shared with the mobile node. This action will force the mobile node to remove any IPv6 address configuration onthat accessthe interface connected to this point- to-point link. 6.9.1.5. Constructing the Proxy Binding UpdateMessage:Message o The mobile access gateway when sending the Proxy Binding Update request to the local mobility anchor MUST construct the message as specified below.Gundavelli, et al. Expires June 27, 2008 [Page 43] Internet-Draft Proxy Mobile IPv6 December 2007IPv6 header (src=Proxy-CoA, dst=LMAA) Mobility header-BU /*P- BU /* P & A flagsare set*/MUST be set */ Mobility Options - Mobile Node Identifier option (mandatory) - Home Network Prefix option (mandatory) -Link-local Address option (Optional) - Timestamp Option (optional) - Mobile Node IdentifierHandoff Indicator option (mandatory) - Access Technology Type option(Mandatory)(mandatory) - Timestamp option (optional) - Mobile Node Interface Identifier option(Optional)(optional) - Link-local Address option (optional) Figure8:11: Proxy Binding Update message format o The Source Address field in the IPv6 header of the message MUST be set to the address configured on the interface of the mobile access gateway.o The Destination AddressWhen there is no Alternate Care-of Address option present in the request, this address will be considered as the Proxy-CoA address for this binding registration request. However, when there is Alternate Care-of Address option present in the request, this address will be not be the considered as the Proxy- CoA address, but the address in the alternate Care-of Address option will be considered as the Proxy-CoA address. o The Destination Address field in the IPv6 header of the message MUST be set to the local mobility anchor address. o The Mobile Node Identifier option [RFC-4283] MUST be present. o The Home Network Prefix option MUST be present.The prefix value MAY be set 0::/0 or to a specific prefix value.Gundavelli (Editor), et al. Expires August 6, 2008 [Page 48] Internet-Draft Proxy Mobile IPv6 February 2008 o TheLink-local AddressHandoff Indicator optionMAYMUST be present.The value MAY be set to ALL_ZERO or the mobile node's link-local address.o The Access Technology Type option MUST be present. o Thevalue MUSTTimestamp option MAY beset to the type of the access technology using which the mobile node is currently attached to the mobile access gateway.present. o The Mobile Node Interface Identifier option MAY be present. oConsiderations from Section 5.5 must be applied for constructing the Timestamp option. oTheMobile Node Identifier option [RFC-4283] MUST be present, the identifier field in theLink-local Address optionMUSTMAY beset to mobile node's identifier, MN-Identifier.present. o If IPsec is used for protecting the signaling messages, the message MUST be protected, using the security association existing between the local mobility anchor and the mobile access gateway.Gundavelli, et al. Expires June 27, 2008 [Page 44] Internet-Draft Proxyo Unlike in Mobile IPv6December 2007[RFC-3775], the Home Address option [RFC- 3775] MUST NOT be present in the IPv6 Destination Options extension header of the Proxy Binding Update message. 6.9.2. Router Solicitation Messages The mobile node may send a Router Solicitation message on the access link whenever the link-layer detects a media change. The Source Address in the IPv6 header of the Router Solicitation message may either be the link-local address of the mobile node or an unspecified address (::). The Router Solicitation message that the mobile node sends is as specified in [RFC-4861]. 1. The mobile access gateway on receiving the Router Solicitation message SHOULD send a Router Advertisement containing the mobile node's home network prefix as the on-link prefix. However, before sending the Router Advertisement message containing the mobile node's home network prefix, it SHOULD complete the binding registration process with the mobile node's local mobility anchor. 2. If the local mobility anchor rejects the binding registration request, or, if the mobile access gateway failed to complete the binding registration process for whatever reasons, the mobile access gateway MUST NOT advertise the mobile node's home network prefix in the Router Advertisement messages that it sends on the access link. However, it MAY choose to advertise a local visited network prefix to enable the mobile node for regular IPv6 access. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 49] Internet-Draft Proxy Mobile IPv6 February 2008 6.9.3.Retransmissions and Rate Limiting The mobile access gatewayDefault-Router Lifetime This section isresponsible for retransmissionsa non-normative section andrate limitingonly provides some general guidance to implementations. In Proxy Mobile IPv6, thebinding registration requests that it sends for updating amobilenode's binding. Implementations MUST followaccess gateway is typically thebelow guidelines. 1. WhenIPv6 default-router for the mobile node on the accessgateway sends a Proxy Binding Update request,link, as itshould useis theconstant, INITIAL_BINDINGACK_TIMEOUT [RFC-3775], for configuringentity that sends theretransmission timer. 2. IfRouter Advertisements on the access link. However, as the mobile node moves from one accessgateway failslink to another, the serving mobile access gateway on those respective links will send the Router Advertisements and using their own link-local address. The mobile node on each of the attached links will receive Router Advertisement messages with avalid matching response within the retransmission interval, it SHOULD retransmitdifferent source address and this makes themessage untilmobile node believe that there is aresponsenew default-router on that access link. The mobile node will certainly detect the previous default-router loss by performing the Neighbor Unreachability Detection procedure per the standard IPv6 ND mechanisms, but it isreceived. However,important that the mobile access gatewayMUST ensureenables the mobile nodeis still attachedto withdraw theconnected link before retransmittingprevious default-router entry at themessage. 3. As specifiedearliest. This action will help inSection 11.8 [RFC-3775],minimizing packet losses during a hand off switch. Following are some considerations that implementations can apply. The Router Lifetime field in the Router Advertisement messages that the mobile access gatewayMUST use an exponential back-off process in whichsends on thetimeout periodaccess link SHOULD be kept to low. In access networks where SEND [RFC-3971] isdoubled upon each retransmission, until eithernot deployed, thenode receivesmobile access gateway can withdraw the previous default-router entry, by sending aresponse orRouter Advertisement using thetimeout period reacheslink-local address that of thevalue MAX_BINDACK_TIMEOUT [RFC-3775]. Theprevious mobile access gatewayGundavelli, et al. Expires June 27, 2008 [Page 45] Internet-Draft Proxy Mobile IPv6 December 2007 MAY continueand with the Router Lifetime field set tosend these messages atvalue zero, then thisslower rate indefinitely. 4. If Timestamp based scheme is in use, the retransmitted Proxy Binding Update messages MUST use the latest timestamp. If Sequence number scheme is in use,will force theretransmitted Proxy Binding Update messages MUST use a Sequence Number value greater than that used forflush of the previoustransmission of this Proxy Binding Update message, justdefault-router entry from the mobile node's cache, as specified in[RFC-3775]. 6.10. Routing Considerations This section describes howSection 6.3.5 [RFC-4861]. However, this approach requires the serving mobile access gatewayhandlesto learn thetraffic to/fromlink-local address of the previous mobile access gateway where the mobile nodethat is attached to onewas handed off. There are other solutions possible for this problem, including the assignment ofits access interface. Proxy-CoA LMAA | | +--+ +---+ +---+ +--+ |MN|----------|MAG|======================|LMA|----------|CN| +--+ +---+ +---+ +--+ IPv6 Tunnel Figure 9:a fixed link-local address for all the mobility entities in a Proxy Mobile IPv6Tunnel 6.10.1. Transport Network The transport network between the local mobility anchordomain and where SEND [RFC-3971] is not deployed. In such scenario, the mobileaccess gateway can be either an IPv6 or IPv4 network.node is not required to update the default-router entry. However, thisspecification only deals with the IPv6 transportis an implementation choice and has no bearing on thecompanion document [ID-IPV4-PMIP6] specifiesprotocol interoperability. Implementations are free to adopt therequired extensions for negotiating IPv4 transportbest approach that suits their target deployments. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 50] Internet-Draft Proxy Mobile IPv6 February 2008 6.9.4. Retransmissions andthe corresponding encapsulation mode for supporting this protocol operation. 6.10.2. Tunneling & Encapsulation ModesRate Limiting TheIPv6 address that amobilenode uses from its home network prefixaccess gateway istopologically anchored atresponsible for retransmissions and rate limiting the binding registration requests that it sends to the local mobility anchor.For aThe Retransmission and the Rate Limiting rules are as specified in [RFC-3775]. However, the following considerations MUST be applied. 1. When the mobilenode to use this address from anaccessnetwork attached togateway sends a Proxy Binding Update request, it should use the constant, INITIAL_BINDINGACK_TIMEOUT [RFC-3775], for configuring the retransmission timer, as specified in Section 11.8 [RFC-3775]. However, the mobile accessgateway, proper tunneling techniques havegateway is not required tobeuse a longer retransmission interval of InitialBindackTimeoutFirstReg as specified inplace. Tunneling hides[RFC-3775] for thenetwork topology and allowsinitial binding registration request. 2. If the mobilenode's IPv6 datagramaccess gateway fails tobe encapsulated asreceive apayload of another IPv6 packet and to be routed betweenvalid matching response for a registration or re-registration message within thelocal mobility anchor andretransmission interval, it SHOULD retransmit the message until a response is received. However, the mobile accessgateway. The Mobile IPv6 base specification [RFC-3775] defines the use of IPv6-over-IPv6 tunneling, between the home agent andgateway MUST ensure the mobile nodeand this specification extends the use ofis still attached to theGundavelli,connected link before retransmitting the message. 3. As specified in Section 11.8 [RFC-3775], the mobile access gateway MUST use an exponential back-off process in which the timeout period is doubled upon each retransmission, until either the node receives a response or the timeout period reaches the value MAX_BINDACK_TIMEOUT [RFC-3775]. The mobile access gateway MAY continue to send these messages at this slower rate indefinitely. 4. If Timestamp based scheme is in use, the retransmitted Proxy Binding Update messages MUST use the latest timestamp. If Sequence number scheme is in use, the retransmitted Proxy Binding Update messages MUST use a Sequence Number value greater than that used for the previous transmission of this Proxy Binding Update message, just as specified in [RFC-3775]. 6.10. Routing Considerations This section describes how the mobile access gateway handles the traffic to/from the mobile node that is attached to one of its access interface. Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page46]51] Internet-Draft Proxy Mobile IPv6December 2007 same tunneling mechanismFebruary 2008 Proxy-CoA LMAA | | +--+ +---+ +---+ +--+ |MN|----------|MAG|======================|LMA|----------|CN| +--+ +---+ +---+ +--+ IPv6 Tunnel Figure 12: Proxy Mobile IPv6 Tunnel 6.10.1. Transport Network The transport network between the local mobility anchor and the mobile accessgateway. On most operating systems, tunnels are implemented as a virtual point-to-point interface. The sourcegateway can be either an IPv6 or IPv4 network. However, this specification only deals with the IPv6 transport and thedestination address ofcompanion document [ID-IPV4-PMIP6] specifies thetwo end points of this virtual interface along withrequired extensions for negotiating IPv4 transport and the corresponding encapsulation modeare specifiedfor supporting thisvirtual interface. Any packet that isprotocol operation. 6.10.2. Tunneling & Encapsulation Modes The IPv6 address that a mobile node uses from its home network prefix is topologically anchored at the local mobility anchor. For a mobile node to use this address from an access network attached to a mobile access gateway, proper tunneling techniques have to be in place. Tunneling hides the network topology and allows the mobile node's IPv6 datagram to be encapsulated as a payload of another IPv6 packet and to be routed between the local mobility anchor and the mobile access gateway. The Mobile IPv6 base specification [RFC-3775] defines the use of IPv6-over-IPv6 tunneling, between the home agent and the mobile node and this specification extends the use of the same tunneling mechanism between the local mobility anchor and the mobile access gateway. On most operating systems, tunnels are implemented as a virtual point-to-point interface. The source and the destination address of the two end points of this virtual interface along with the encapsulation mode are specified for this virtual interface. Any packet that is routed over this interface gets encapsulated with the outer header and the addresses as specified for that point to point tunnel interface. For creating a point to point tunnel to any local mobility anchor, the mobile access gateway may implement a tunnel interface with the source address field set to its Proxy-CoA address and the destination address field set to the LMA address. The following are the supported packet encapsulation modes that can be used by the mobile access gateway and the local mobility anchor for routing mobile node's IPv6 datagrams. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 52] Internet-Draft Proxy Mobile IPv6 February 2008 o IPv6-In-IPv6 - IPv6 datagram encapsulated in an IPv6 packet [RFC- 2473]. o IPv6-In-IPv4 - IPv6 datagram encapsulation in an IPv4 packet. The details on how this mode is negotiated is specified in [ID-IPV4- PMIP6]. o IPv6-In-IPv4-UDP - IPv6 datagram encapsulation in an IPv4 UDP packet. This mode is specified in [ID-IPV4-PMIP6]. 6.10.3. Local RoutingState The following section explains the routing state forIf there is data traffic between a visiting mobile nodeonand a correspondent node that is locally attached to an access link connected to the mobile accessgateway. Thisgateway, the mobile access gateway MAY optimize on the delivery efforts by locally routingstate reflects only one specific way of implementationthe packets andone MAY chooseby not reverse tunneling them toimplement it in other ways.the mobile node's local mobility anchor. Thepolicy based route defined below acts as a traffic selection ruleconfiguration variable, EnableMAGLocalRouting MAY be used forrouting acontrolling this aspect. However, in some systems, this may have an implication on the mobile node's accounting and policy enforcement as the local mobility anchor is not in the path for that trafficthrough a specific tunnel created betweenand it will not be able to apply any traffic policies or do any accounting for those flows. This decision of path optimization SHOULD be based on the policy configured on the mobile accessgateway and thatgateway, but enforced by the mobile node's local mobilityanchor and with the specific encapsulation mode, as negotiated.anchor. Thebelow example identifiesspecific details on how this is achieved are beyond of therouting statescope of this document. 6.10.4. Tunnel Management All the considerations mentioned in Section 5.6.1 fortwo visiting mobile nodes, MN1 and MN2 with their respectivethe tunnel management on the local mobilityanchors LMA1 and LMA2. For all traffic fromanchor apply for the mobilenode, identified byaccess gateway as well. 6.10.5. Forwarding Rules Forwarding Packets sent to the Mobile Node's Home Network: o On receiving a packet from the bi-directional tunnel established with the mobile node'sMAC address, ingresslocal mobility anchor, the mobile access gateway MUST use the destination address of the inner packet for forwarding it on the interfaceor sourcewhere the destination network prefix(MN-HNP) to _ANY_DESTINATION_ route viais hosted. The mobile access gateway MUST remove the outer header before forwarding the packet. If the mobile access gateway cannot find the connected interfacetunnel0, next-hop LMAA. Gundavelli, et al. Expires June 27, 2008 [Page 47] Internet-Draft Proxy Mobile IPv6 December 2007 +==================================================================+ | Packet Source | Destination Address | Destination Interface | +==================================================================+ | MAC_Address_MN1, | _ANY_DESTINATION_ | Tunnel0 | | (IPv6 Prefix or |----------------------------------------------| | Input Interface) | Locally Connected | Tunnel0 | +------------------------------------------------------------------+ | MAC_Address_MN2, | _ANY_DESTINATION_ | Tunnel1 | + (IPv6 Prefix or -----------------------------------------------| | Input Interface | Locally Connected | direct | +------------------------------------------------------------------+ Figure 10: Example - Policy based Route Table +==================================================================+ | Interface | Source Address | Destination Address | Encapsulation | +==================================================================+ | Tunnel0 | Proxy-CoA | LMAA1 | IPv6-in-IPv6 | +------------------------------------------------------------------+ | Tunnel1 |IPv4-Proxy-CoA | IPv4-LMA2 | IPv6-in-IPv4 | +------------------------------------------------------------------+ Figure 11: Example - Tunnel Interface Table 6.10.4. Local Routing If there is data traffic between a visiting mobile node and a correspondent node that is locally attached to an access link connected to the mobile access gateway, the mobile access gateway MAY optimize on the delivery efforts by locally routing the packets and by not reverse tunneling them to the mobile node's local mobility anchor. The configuration variable, EnableMAGLocalRouting MAY be used for controlling this aspect. However, in some systems, this may have an implication on the mobile node's accounting and policy enforcement as the local mobility anchor is not in the pathfor thattraffic and it will not be able to apply any traffic policies or do any accounting for those flows. This decision of path optimization SHOULD be based on the policy configured on the mobile access gateway, but enforced by the mobile node's local mobility anchor. The specific details on how this is achieved are beyond of the scope of this document. Gundavelli, et al. Expires June 27, 2008 [Page 48] Internet-Draft Proxy Mobile IPv6 December 2007 6.10.5. Tunnel Management All the considerations mentioned in Section 5.6.1 for the tunnel management on the local mobility anchor apply for the mobile access gateway as well. 6.10.6. Forwarding Rules Forwarding Packets sent to the Mobile Node's Home Network: o On receiving a packet from the bi-directional tunnel established with the mobile node's local mobility anchor, the mobile access gateway MUST use the destination address of the inner packet for forwarding it on the interface where the destination network prefix is hosted. The mobile access gateway MUST remove the outer header before forwarding the packet. If the mobile access gateway cannot find the connected interface for that destination address, it MUST silently drop the packet. For reporting an error in such a scenario, in the form of ICMP control message, the considerations from Generic Packet Tunneling specification [RFC- 2473] must be applied. o On receiving a packet from a correspondent node that is locally connected and which is destined to a mobile node that is on another locally connected access link, the mobile access gateway MUST check the configuration variable, EnableMAGLocalRouting, to ensure the mobile access gateway is allowed to route the packet directly to the mobile node. If the mobile access gateway is not allowed to route the packet directly, it MUST route the packet through the bi-directional tunnel established between itself and the mobile node's local mobility anchor. Otherwise, it can route the packet directly to the mobile node. Forwarding Packets Sent by the Mobile Node: o On receiving a packet from a mobile node connected to its access link, the mobile access gateway MUST ensure that there is an established binding for that mobile node with its local mobility anchor before forwarding the packet directly to the destination or before tunneling the packet to the mobile node's local mobility anchor. o On receiving a packet from a mobile node connected to its access link to a destination that is locally connected, the mobile access gateway MUST check the configuration variable, EnableMAGLocalRouting, to ensure the mobile access gateway is allowed to route the packet directly to the destination. If the mobile access gateway is not allowed to route the packet directly, Gundavelli, et al. Expires June 27, 2008 [Page 49] Internet-Draft Proxy Mobile IPv6 December 2007 it MUST route the packet through the bi-directional tunnel established between itself and the mobile node's local mobility anchor. Otherwise, it can route the packet directly to the destination. o On receiving a packet from the mobile node connected to its access link, to a destination that is not directly connected, the packet MUST be forwarded to the local mobility anchor through the bi- directional tunnel established between itself and the mobile node's local mobility anchor. However, the packets that are sent with the link-local source address MUST NOT be forwarded. The format of the tunneled packet is shown below. However, when using IPv4 transport, the format of the tunneled packet is as described in [ID-IPV4-PMIP6]. IPv6 header (src= Proxy-CoA, dst= LMAA /* Tunnel Header */ IPv6 header (src= MN-HoA, dst= CN ) /* Packet Header */ Upper layer protocols /* Packet Content*/ Figure 12: Tunneled Packets from MAG to LMA 6.11. Supporting DHCPv6 based Address Configuration on the Access Link This section explains how Stateful Address Configuration using DHCPv6 can be enabled on the access link attached to a mobile access gateway and how a mobile node attached to that link can obtain an address from its home network prefix using DHCPv6. o For supporting Stateful Address Configuration using DHCPv6, the DHCPv6 relay agent [RFC-3315] service MUST be enabled on each of the access links in the Proxy Mobile IPv6 domain. Further, as specified in Section 20 [RFC-3315], the relay agent should be configured to use a list of destination addresses, which MAY include unicast addresses, the All_DHCP_Servers multicast address, or other addresses selected by the network administrator. o The DHCPv6 server in the Proxy Mobile IPv6 domain can be configured with a list of prefix pools (P1, P2, ..., Pn). Each one of these prefix pools corresponds to a home network prefix that a local mobility anchor allocates to a mobile node in that domain. However, the DHCPv6 server will not know the relation between a given address pool and a mobile node to whichdestination address, it MUST silently drop thecorresponding prefix is allocated. It just views these pools as prefixes hosted on different linkspacket. For reporting an error inthat domain. Gundavelli,such a scenario, in the form of ICMP control message, the Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page50]53] Internet-Draft Proxy Mobile IPv6December 2007February 2008 considerations from Generic Packet Tunneling specification [RFC- 2473] must be applied. oWhenOn receiving amobilepacket from a correspondent nodesendsthat is locally connected and which is destined to aDHCPv6 request message, the DHCP relay agent functionmobile node that is ontheanother locally connected accesslink will setlink, thelink-address field inmobile access gateway MUST check theDHCP messageconfiguration variable, EnableMAGLocalRouting, toan address inensure the mobilenode's home network prefix, so as to provide a prefix hintaccess gateway is allowed to route theDHCP Server for the address pool selection. The DHCP server on receiving the request frompacket directly to the mobilenode, will allocate an address from the prefix pool present in the link-address field of the request. o Oncenode. If the mobilenode obtains an address and moves to a different link and sends a DHCP request, the DHCP relay agent on the new link will set the prefix hint in the DHCP messagesaccess gateway is not allowed to route themobile node's home network prefix. The DHCP server will identify the client frompacket directly, it MUST route theClient-DUID option and present inpacket through therequestbi-directional tunnel established between itself andwill allocate the same address as before. o The DHCP based address configuration is not recommended for deployments wherethe mobile node's local mobilityanchor andanchor. Otherwise, it can route themobile access gateways are located in different administrative domains. For this configurationpacket directly towork, allthe mobileaccess gateways innode. Forwarding Packets Sent by theProxyMobileIPv6 domain should be able to ensure that the DHCP requestsNode: o On receiving a packet from agivenmobile nodeanchored on any ofconnected to its access link, the mobile accesslinks ingateway MUST ensure thatdomain, will always be handled bythere is an established binding for that mobile node with its local mobility anchor before forwarding thesame DHCP server. o The DHCP server should be configuredpacket directly tooffer low address lease times. A lease time that is too large preventstheDHCP server from reclaimingdestination or before tunneling theaddress even afterpacket to the mobile node's local mobilityanchor deletesanchor. o On receiving a packet from a mobile node connected to its access link to a destination that is locally connected, the mobilenode's binding cache entry. 6.12. Home Network Prefix Renumbering Ifaccess gateway MUST check the configuration variable, EnableMAGLocalRouting, to ensure the mobilenode's home network prefix gets renumbered or becomes invalid duringaccess gateway is allowed to route themiddle of a mobility session,packet directly to the destination. If the mobile access gateway is not allowed to route the packet directly, it MUSTwithdrawroute theprefix by sending a Router Advertisement onpacket through theaccess link with zero prefix lifetime forbi-directional tunnel established between itself and the mobile node'shome network prefix. Also, thelocal mobilityanchor andanchor. Otherwise, it can route the packet directly to the destination. o On receiving a packet from the mobile node connected to its accessgateway MUST delete the routing state forlink, to a destination thatprefix. However,is not directly connected, thespecific details on howpacket MUST be forwarded to the local mobility anchornotifiesthrough themobile access gateway aboutbi- directional tunnel established between itself and the mobile node'shome network prefix renumberinglocal mobility anchor. However, the packets that areoutsidesent with thescopelink-local source address MUST NOT be forwarded. The format ofthis document. 6.13. Mobile Node Detachment Detection and Resource Cleanup Before sending athe tunneled packet is shown below. Additionally, when using IPv4 transport, the format of the tunneled packet is as described in [ID-IPV4-PMIP6]. IPv6 header (src= Proxy-CoA, dst= LMAA /* Tunnel Header */ IPv6 header (src= MN-HoA, dst= CN ) /* Packet Header */ Upper layer protocols /* Packet Content*/ Gundavelli (Editor), et al. Expires August 6, 2008 [Page 54] Internet-Draft ProxyBinding Update messageMobile IPv6 February 2008 Figure 13: Tunneled Packets from MAG to LMA 6.11. Supporting DHCPv6 based Address Configuration on thelocal mobility anchor for extendingAccess Link This section explains how Stateful Address Configuration using DHCPv6 can be enabled on thelifetime of a currently existing binding ofaccess link attached to a mobilenode, the mobileaccess gatewayMUST make sure theand how a mobile nodeis stillattached to that link can obtain an address from its home network prefix using DHCPv6. o For supporting Stateful Address Configuration using DHCPv6, the DHCPv6 relay agent [RFC-3315] service MUST be enabled on each of the access links in the Proxy Mobile IPv6 domain. Further, as specified in Section 20 [RFC-3315], the relay agent should be configured to use a list of destination addresses, which MAY include unicast addresses, theconnected linkAll_DHCP_Servers multicast address, or other addresses selected byusing some reliable method. Ifthemobile access gateway cannot predictably detectnetwork administrator. o The DHCPv6 server in theGundavelli, et al. Expires June 27, 2008 [Page 51] Internet-DraftProxy Mobile IPv6December 2007 presencedomain can be configured with a list ofthe mobile node on the connected link, it MUST NOT attempt to extend the registration lifetimeprefix pools (P1, P2, ..., Pn). Each one ofthethese prefix pools corresponds to a home network prefix that a local mobility anchor allocates to a mobilenode. Further,node insuch scenario, the mobile access gateway SHOULD terminatethat domain. However, thebinding ofDHCPv6 server will not know the relation between a given address pool and a mobile nodeby sending a Proxy Binding Update messageto which themobile node's local mobility anchor with lifetime value set to 0.corresponding prefix is allocated. ItMUST also remove any local state suchjust views these pools asthe Binding Update List created forprefixes hosted on different links in thatmobile node. The specific detection mechanism of the loss ofdomain. o When avisitingmobile nodeonsends a DHCPv6 request message, theconnected link is specific toDHCP relay agent function on the access linkbetweenwill set themobile node andlink-address field in themobile access gateway and is outsideDHCP message to an address in thescope of this document. Typically, there are various link-layer specific events specificmobile node's home network prefix, so as toeach access technology thatprovide a prefix hint to the DHCP Server for themobile access gateway can dependaddress pool selection. The DHCP server onfor detectingreceiving thenode loss. In general,request from the mobileaccess gateway can depend on one or more ofnode, will allocate an address from thefollowing methods forprefix pool present in thedetection presencelink-address field of the request. o Once the mobile nodeon the connected link: o Link-layer event specificobtains an address and moves to a different link and sends a DHCP request, theaccess technology o PPP Session termination eventDHCP relay agent onpoint-to-pointthe new linktypes o IPv6 Neighbor Unreachability Detection eventwill set the prefix hint in the DHCP messages to the mobile node's home network prefix. The DHCP server will identify the client fromIPv6 stackthe Client-DUID option and present in the request and will allocate the same address as before. oNotification event fromThe DHCP based address configuration is not recommended for deployments where the local mobility anchor6.14. Allowing networkand the mobile access gateways are located in different administrative domains. For this configuration toother IPv6 nodes In somework, all the mobile access gateways in the Proxy Mobile IPv6deployments, network operators may wantdomain should be able toprovisionensure that the DHCP requests from a given mobile node anchored on any of the accessgatewaylinks in that domain, will always be handled by the same DHCP Gundavelli (Editor), et al. Expires August 6, 2008 [Page 55] Internet-Draft Proxy Mobile IPv6 February 2008 server. o The DHCP server should be configured to offernetwork-basedlow address lease times. A lease time that is too large prevents the DHCP server from reclaiming the address even after the local mobilitymanagement service only to some visitinganchor deletes the mobilenodes and enable just regular IP access to some other nodes. This requiresnode's binding cache entry. 6.12. Home Network Prefix Renumbering If the mobile node's home networkto have control on when to enable network-based mobility management service toprefix gets renumbered or becomes invalid during the middle of a mobility session, the mobilenode and when to enable regular IPv6 access. This specification does not disallow such configuration. Upon detectingaccess gateway MUST withdraw the prefix by sending amobile nodeRouter Advertisement onitsthe access link with zero prefix lifetime for the mobile node's home network prefix. Also, the local mobility anchor andafter policy considerations,the mobile access gateway MUSTdetermine if network- based mobility management service should be offered to that mobile node. Ifdelete themobile node is entitledrouting state fornetwork-basedthat prefix. However, the specific details on how the local mobilitymanagement service, thenanchor notifies the mobile access gatewaymust ensureabout the mobilenode believes it is on itsnode's homelink, as explained in various sectionsnetwork prefix renumbering are outside the scope of thisspecification. If the mobile node is not entitled fordocument. 6.13. Mobile Node Detachment Detection and Resource Cleanup Before sending a Proxy Binding Update message to thenetwork-basedlocal mobilitymanagement service, as determined from the policy considerations, the mobile access gateway MAY choose to offer regular IPv6 access toanchor for extending the lifetime of a currently existing binding of a mobilenode and in such scenarionode, thenormal IPv6 considerations Gundavelli, et al. Expires June 27, 2008 [Page 52] Internet-Draft Proxy Mobile IPv6 December 2007 apply. If IPv6mobile accessis enabled,gateway MUST make sure the mobile nodeSHOULD be ableis still attached toobtain an IPv6 addressthe connected link by usingnormal IPv6 address configuration procedures. The obtained address must be from a local visitor network prefix. This essentially ensures thatsome reliable method. If the mobile access gatewayfunctions as a normal access router to acannot predictably detect the presence of the mobile nodeattachedon the connected link, it MUST NOT attempt toits access link and with out impacting its host-based mobility protocol operation. 7. Mobile Node Operation This non-normative section explainsextend the registration lifetime of the mobilenode's operationnode. Further, ina Proxy Mobile IPv6 domain. 7.1. Moving into a Proxy Mobile IPv6 Domain Once asuch scenario, the mobile access gateway SHOULD terminate the binding of the mobile nodeentersby sending a ProxyMobile IPv6 domain and attachesBinding Update message toan access network,the mobileaccess gatewaynode's local mobility anchor with lifetime value set to 0. It MUST also remove any local state such as the Binding Update List entry created for that mobile node. The specific detection mechanism of the loss of a visiting mobile node on theaccessconnected linkdetectsis specific to theattachment ofaccess link between the mobile node andcompletes the binding registration withthe mobilenode's local mobility anchor. If the binding update operationaccess gateway and issuccessfully performed,outside the scope of this document. Typically, there are various link-layer specific events specific to each access technology that the mobile access gatewaywill createcan depend on for detecting therequired state and setupnode loss. In general, the mobile access gateway can depend on one or more of thedata pathfollowing methods for themobile node's data traffic. Ifdetection presence of the mobile nodeis IPv6 enabled,onattachingthe connected link: o Link-layer event specific to the accesslink, it will typically send Router Solicitation message [RFC-4861]. The mobile access gatewaytechnology o PPP Session termination event onthe accesspoint-to-point linkwill respond to the Router Solicitation message with a Router Advertisement. The Router Advertisement will havetypes Gundavelli (Editor), et al. Expires August 6, 2008 [Page 56] Internet-Draft Proxy Mobile IPv6 February 2008 o IPv6 Neighbor Unreachability Detection event from IPv6 stack o Notification event from themobile node's homelocal mobility anchor 6.14. Allowing networkprefix, default-router address andaccess to otheraddress configuration parameters. IfIPv6 nodes In some Proxy Mobile IPv6 deployments, network operators may want to provision the mobile access gatewayon the access link, receives a Router Solicitation message from the mobile node, before it completed the signaling with the mobile node's localto offer network-based mobilityanchor, themanagement service only to some visiting mobile nodes and enable just regular IP accessgateway may not knowto some other nodes. This requires themobile node's homenetworkprefixto have control on when to enable network-based mobility management service to a mobile node andmay not be ablewhen toemulate theenable regular IPv6 access. This specification does not disallow such configuration. Upon detecting a mobilenode's home linknode ontheits accesslink. In such scenario,link and after policy considerations, the mobilenode may notice a slight delay before it receives a Router Advertisement message.access gateway MUST determine if network- based mobility management service should be offered to that mobile node. If thereceived Router Advertisement has the Managed Address Configuration flag set,mobile node is entitled for network-based mobility management service, then the mobilenode, as it would normally do, will send a DHCPv6 Request [RFC-3315]. The DHCP relay service enabled on thataccesslink willgateway must ensure the mobile nodewill obtain its IPv6 address as a lease frombelieves it is on its homenetwork prefix.link, as explained in various sections of this specification. If thereceived Router Advertisement does not have the Managed Address Configuration flag set and if themobile node isallowed to use an autoconfigured address,not entitled for the network-based mobility management service, as determined from the policy considerations, the mobilenode will be ableaccess gateway MAY choose toobtain Gundavelli, et al. Expires June 27, 2008 [Page 53] Internet-Draft Proxy Mobile IPv6 December 2007 anoffer regular IPv6address using an interface identifier generated as peraccess to theAutoconf specification [RFC-4862] or as permobile node and in such scenario thePrivacy Extensions specification [RFC-4941].normal IPv6 considerations apply. If IPv6 access is enabled, the mobile nodeis IPv4 enabled and if the network permits, it willSHOULD be able to obtainthe IPv4an IPv6 addressconfiguration for the connected interface byusingDHCP [RFC-2131]. The details related to IPv4 support is specified in the companion document [ID-IPV4-PMIP6]. Once thenormal IPv6 address configurationis complete,procedures. The obtained address must be from a local visitor network prefix. This essentially ensures that the mobilenode can continue to use this address configuration as longaccess gateway functions asit isa normal access router to a mobile node attached to its access link and with out impacting its host-based mobility protocol operation. 7. Mobile Node Operation This non-normative section explains thenetwork that ismobile node's operation inthe scope of thata Proxy Mobile IPv6 domain.7.2. Roaming in the7.1. Moving into a Proxy Mobile IPv6 DomainAfter obtaining the address configuration in theWhen a mobile node enters a Proxy Mobile IPv6domain, as the mobile node movesdomain andchanges its point of attachment from oneattaches to an access network, the mobile access gatewaytoon theother, it can still continue to useaccess link detects thesame address configuration. As long asattachment of theattached access networkmobile node and completes the binding registration with the mobile node's local mobility anchor. If the binding update operation isinsuccessfully performed, thescope of thatmobile access gateway will create the required state and setup the data path for Gundavelli (Editor), et al. Expires August 6, 2008 [Page 57] Internet-Draft Proxy Mobile IPv6domain,February 2008 the mobilenode will always detect the same link, where it obtained its initial address configuration.node's data traffic. If the mobile nodeperforms DHCP operation,is IPv6 enabled, on attaching to the access link, it willalways obtain the same address as before. However, thetypically send Router Solicitation message [RFC-4861]. The mobilenodeaccess gateway on the access link willalways detectrespond to the Router Solicitation message with anew default-router on each connected link, but still advertisingRouter Advertisement. The Router Advertisement will have the mobile node's home networkprefix as the on-link prefixprefix, default-router address andwith theother address configurationparameters consistent with its home link properties. 7.3. IPv6 Host Protocol Parameters This specification does not require any changes toparameters. If the mobile access gateway on the access link, receives a Router Solicitation message from the mobile node, before it completed the signaling with the mobile node'sIP stack. It assumeslocal mobility anchor, the mobilenode to be a normal IPv4/IPv6 node, with its protocol operation consistent withaccess gateway may not know therespective specifications. However, for achieving protocol efficiencymobile node's home network prefix andfor faster hand-offs, implementationsmaychoosenot be able toadjustemulate thefollowing IPv6 operating parametersmobile node's home link on the access link. In such scenario, the mobile nodebe adjusted to the below recommended values. Lower Default-Router List Cache Time-out: As per the base IPv6 specification [RFC-4861], each IPv6 host is required to maintain certain host data structures includingmay notice a slight delay before it receives aDefault-Router list. This is the list of on-link routers that have sentRouter Advertisementmessages and are eligible to be default Gundavelli, et al. Expires June 27, 2008 [Page 54] Internet-Draft Proxy Mobile IPv6 December 2007 routers on that link. The Router Lifetime field inmessage. If the received Router Advertisementdefineshas the Managed Address Configuration flag set, thelife of this entry. In case of Proxy Mobile IPv6, when amobilenode moves from onenode, as it would normally do, will send a DHCPv6 Request [RFC-3315]. The DHCP relay service enabled on that access linkto another,will ensure thesourcemobile node will obtain its IPv6 addressofas a lease from its home network prefix. If the received Router Advertisementmessages advertisingdoes not have themobile node's home network prefix will be from a different link-local addressManaged Address Configuration flag set andthus makingif the mobile nodebelieve that thereisa new default-router onallowed to use an autoconfigured address, thelink. It is important thatmobile node will be able to obtain an IPv6 address using an interface identifier generated as per themobile node usesAutoconf specification [RFC-4862] or as per thenewly learnt default-router and notPrivacy Extensions specification [RFC-4941]. If thepreviously known default-router. Themobile nodemust update its default-router list with the new default router entryis IPv4 enabled andmust age outif thepreviously learnt default router entry from its cache, justnetwork permits, it will be able to obtain the IPv4 address configuration as specified inSection 6.3.5 [RFC-4861]. This action will help in minimizing packet losses during a hand off switch. On detecting a reachability problem, the mobile node will certainly detectthedefault-router loss by performingcompanion document [ID-IPV4-PMIP6]. Once theNeighbor Unreachability Detection procedure, but itaddress configuration isimportant thatcomplete, the mobile nodetimes out the previous default router entry at the earliest. If a given IPv6 host implementation has the provision to adjust these flush timers, still conformingcan continue tothe base IPv6 ND specification,use this address configuration as long as it isdesirable to keep the flush-timersattached tosuittheabove consideration. In accessnetworkwhere SEND [RFC-3971]that isnot deployed,in themobile access gateway may withdrawscope of that Proxy Mobile IPv6 domain. 7.2. Roaming in theprevious default-router entry, by sending a Router Advertisement usingProxy Mobile IPv6 Domain After obtaining thelink-localaddressthat ofconfiguration in thepreviousProxy Mobile IPv6 domain, as the mobile node moves and changes its point of attachment from one mobile access gatewayand with the Router Lifetime field settovalue 0, then this will forcetheflush ofother, it can still continue to use thePrevious Default-Router entry fromsame address configuration. As long as themobile node's cache. This certainly requires context-transfer mechanismsattached access network is inplace for notifying the link- local addressthe scope of that Proxy Mobile IPv6 domain, thedefault-router onmobile node will always detect theprevious link tosame link, where it obtained its initial address configuration. If the mobileaccess gateway on the new link. There are other solutions possible for this problem, includingnode performs DHCP operation, it will always obtain theassignment of a fixed link-localsame addressfor all the mobility entities in aas before. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 58] Internet-Draft Proxy Mobile IPv6domain and where SEND [RFC-3971] is not deployed. In such scenario,February 2008 However, the mobile nodeis not required to update thewill always detect a new default-routerentry. However, this is an implementation choice and has no bearingon each connected link, but still advertising theprotocol interoperability. Implementations are free to adoptmobile node's home network prefix as thebest approach that suits their target deployments.on-link prefix and with the other configuration parameters consistent with its home link properties. 8. Message Formats This section defines extensions to the Mobile IPv6 [RFC-3775] protocol messages.Gundavelli, et al. Expires June 27, 2008 [Page 55] Internet-Draft Proxy Mobile IPv6 December 20078.1. Proxy Binding Update Message 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence # | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |A|H|L|K|M|R|P| Reserved | Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Mobility options . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ A Binding Update message that is sent by a mobile access gateway to a local mobility anchor is referred to as the "Proxy Binding Update" message. A new flag (P) is included in the Binding Update message. The rest of the Binding Update message format remains the same as defined in [RFC-3775] and with the additional (R) and (M) flags as specified in [RFC-3963] and [RFC-4140] respectively. Proxy Registration Flag (P) Gundavelli (Editor), et al. Expires August 6, 2008 [Page 59] Internet-Draft Proxy Mobile IPv6 February 2008 A new flag (P) is included in the Binding Update message to indicate to the local mobility anchor that the Binding Update message is a proxy registration. The flag MUST be set to the value of 1 for proxy registrations and MUST be set to 0 for direct registrations sent by a mobile node. Mobility Options Variable-length field of such length that the complete Mobility Header is an integer multiple of 8 octets long. This field contains zero or more TLV-encoded mobility options. The encoding and format of defined options are described in Section 6.2 [RFC- 3775]. The local mobility anchor MUST ignore and skip any options which it does not understand.Gundavelli, et al. Expires June 27, 2008 [Page 56] Internet-Draft Proxy Mobile IPv6 December 2007As per this specification, the following mobility options are valid in a Proxy Binding Update message: Mobile Node Identifier option Home Network Prefix optionLink-local AddressHandoff Indicator optionMobile Node Identifier OptionAccess Technology Type option Timestamp option Mobile Node Interface Identifier optionTimestampLink-local Address option For descriptions of other fields present in this message, refer to section 6.1.7 [RFC-3775]. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 60] Internet-Draft Proxy Mobile IPv6 February 2008 8.2. Proxy Binding Acknowledgement Message 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Status |K|R|P|Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence # | Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Mobility options . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ A Binding Acknowledgement message that is sent by a local mobility anchor to a mobile access gateway is referred to as the "Proxy Binding Acknowledgement" message. A new flag (P) is included in the Binding Acknowledgement message. The rest of the Binding Acknowledgement message format remains the same as defined in [RFC- 3775] and with the additional (R) and (M) flags as specified in [RFC- 3963] and [RFC-4140] respectively. Proxy Registration Flag (P)Gundavelli, et al. Expires June 27, 2008 [Page 57] Internet-Draft Proxy Mobile IPv6 December 2007A new flag (P) is included in the Binding Acknowledgement message to indicate that the local mobility anchor that processed the corresponding Proxy Binding Update message supports proxy registrations. The flag is set only if the corresponding Proxy Binding Update had the Proxy Registration Flag (P) set to value of 1. Mobility Options Variable-length field of such length that the complete Mobility Header is an integer multiple of 8 octets long. This field contains zero or more TLV-encoded mobility options. The encoding and format of defined options are described in Section 6.2 [RFC- 3775]. The mobile access gateway MUST ignore and skip any options which it does not understand. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 61] Internet-Draft Proxy Mobile IPv6 February 2008 As per this specification, the following mobility options are valid in a Proxy Binding Acknowledgement message: Mobile Node Identifier option Home Network Prefix optionLink-local Address option Mobile Node IdentifierHandoff Indicator option Access Technology Type option Timestamp option Mobile Node Interface Identifier optionTimestampLink-local Address option Status 8-bit unsigned integer indicating the disposition of the Proxy Binding Update. Values of the Status field less than 128 indicate that the Proxy Binding Update was accepted by the local mobility anchor. Values greater than or equal to 128 indicate that the binding registration was rejected by the local mobility anchor. Section8.88.9 defines the Status values that can used in Proxy Binding Acknowledgement message. For descriptions of other fields present in this message, refer to the section 6.1.8 [RFC-3775]. 8.3. Home Network Prefix Option A new option, Home Network Prefix Option is defined for using it in the Proxy Binding Update and Proxy Binding Acknowledgement messagesGundavelli, et al. Expires June 27, 2008 [Page 58] Internet-Draft Proxy Mobile IPv6 December 2007exchanged between a local mobility anchor and a mobile access gateway. This option is used for exchanging the mobile node's home network prefix information. The Home Network Prefix Option has an alignment requirement of 8n+4. Its format is as follows: Gundavelli (Editor), et al. Expires August 6, 2008 [Page 62] Internet-Draft Proxy Mobile IPv6 February 2008 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Home Network Prefix + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type <IANA> Length 8-bit unsigned integer indicating the length of the option in octets, excluding the type and length fields. This field MUST be set to 18. Reserved (R) This 8-bit field is unused for now. The value MUST be initialized to 0 by the sender and MUST be ignored by the receiver. Prefix Length 8-bit unsigned integer indicating the prefix length of the IPv6 prefix contained in the option. Home Network Prefix A sixteen-byte field containing the mobile node's IPv6 Home Network Prefix.Gundavelli,8.4. Handoff Indicator Option A new option, Handoff Indicator Option is defined for using it in the Proxy Binding Update and Proxy Binding Acknowledgement messages exchanged between a local mobility anchor and a mobile access gateway. This option is used for exchanging the mobile node's handoff related hints. Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page59]63] Internet-Draft Proxy Mobile IPv6December 2007 8.4.February 2008 The Handoff Indicator Option has no alignment requirement. Its format is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Reserved (R) | HI | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type <IANA> Length 8-bit unsigned integer indicating the length of the option in octets, excluding the type and length fields. This field MUST be set to 2. Reserved (R) This 8-bit field is unused for now. The value MUST be initialized to 0 by the sender and MUST be ignored by the receiver. Handoff Indicator (HI) A 8-bit field that specifies the type of handoff. The values (0 - 255) will be allocated and managed by IANA. The following values are currently reserved. 0: Reserved 1: Attachment over a new interface 2: Handoff between two different interfaces of the mobile node 3: Handoff between mobile access gateways for the same interface 4: Handoff state unknown 5: Handoff state not changed (Re-registration) 8.5. Access Technology Type Option A new option, Access Technology Type Option is defined for using it in the Proxy Binding Update and Proxy Binding Acknowledgement messages exchanged between a local mobility anchor and a mobile access gateway. This option is used for exchanging the type of the access technology using which the mobile node is currently attached Gundavelli (Editor), et al. Expires August 6, 2008 [Page 64] Internet-Draft Proxy Mobile IPv6 February 2008 to the mobile access gateway. The Access Technology Type Option has no alignment requirement. Its format is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length |Acc TechReserved (R) |HIATT |Reserved|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type <IANA> Length 8-bit unsigned integer indicating the length of the option in octets, excluding the type and length fields. This field MUST be set to 2. Reserved (R) This 8-bit field is unused for now. The value MUST be initialized to 0 by the sender and MUST be ignored by the receiver. Access Technology Type(Acc Tech)(ATT) A 8-bit field that specifies the access technology through which the mobile node is connected to the access link on the mobile access gateway. The values0-255(0 - 255) will be allocated and managed by IANA. The following values are currently reserved for the below specified access technology types.0x00:0: Reserved0x01:1: Virtual0x02:2: PPP0x02:3: 802.3 (Ethernet)0x03: 802.11a 0x04: 802.11b 0x05: 802.11g 0x06:4: 802.11a/b/g 5: 802.16eGundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page60]65] Internet-Draft Proxy Mobile IPv6December 2007 0x07: CDMA2000 1xEV-DO Release 0 0x08: CDMA2000 1xEV-DO Revision A 0x09: CDMA2000 1xEV-DO Revision B 0x0a: 3GPP LTE Handoff Indicator (HI) A 3-bit field that specifies the type of handoff. The values (0-3) will be allocated and managed by IANA. The following values are currently reserved. 0: Reserved 1: Attachment over a new interface 2: Handoff between interfaces 3: Handoff between mobile access gateways for the same interface 4: Handoff state unknown Reserved (R) This 5-bit field is unused for now. The value MUST be initialized to 0 by the sender and MUST be ignored by the receiver. 8.5.February 2008 8.6. Mobile Node Interface Identifier Option A new option, Mobile Node Interface Identifier Option is defined for using it in the Proxy Binding Update and Proxy Binding Acknowledgement messages exchanged between a local mobility anchor and a mobile access gateway. This option is used for exchanging the mobile node's interface identifier. The format of the Interface Identifier option when the interface identifier is 8 bytes is shown below. When the size is different, the option MUST be aligned appropriately, as per mobility option alignment requirements specified in [RFC-3775].Gundavelli, et al. Expires June 27, 2008 [Page 61] Internet-Draft Proxy Mobile IPv6 December 20070 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + Interface Identifier + . ... . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type <IANA> Length 8-bit unsigned integer indicating the length of the option in octets, excluding the type and length fields.This field MUST be set to 10.Reserved This field is unused for now. The value MUST be initialized to 0 by the sender and MUST be ignored by the receiver. Interface Identifier A variable length field containing the mobile node's interface identifier.8.6.The content and format of this field (including byte and bit ordering) is as specified in Section 4.6 [RFC-4861] for carrying Link-Layer Address. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 66] Internet-Draft Proxy Mobile IPv6 February 2008 8.7. Link-local Address Option A new option, Link-local Address Option is defined for using it in the Proxy Binding Update and Proxy Binding Acknowledgement messages exchanged between a local mobility anchor and a mobile access gateway. This option is used for exchanging the mobile node's link- local address. The Link-local Address option has an alignment requirement of 8n+6. Its format is as follows:Gundavelli, et al. Expires June 27, 2008 [Page 62] Internet-Draft Proxy Mobile IPv6 December 20070 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Link-local Address + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type <IANA> Length 8-bit unsigned integer indicating the length of the option in octets, excluding the type and length fields. This field MUST be set to 16. Link-local Address A sixteen-byte field containing the mobile node's link-local address.8.7.8.8. Timestamp Option A new option, Timestamp Option is defined for use in the Proxy Binding Update and Proxy Binding Acknowledgement messages. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 67] Internet-Draft Proxy Mobile IPv6 February 2008 The Timestamp option has an alignment requirement of 8n+2. Its format is as follows:Gundavelli, et al. Expires June 27, 2008 [Page 63] Internet-Draft Proxy Mobile IPv6 December 20070 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 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + Timestamp + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type <IANA> Length 8-bit unsigned integer indicating the length in octets of the option, excluding the type and length fields. The value for this field MUST be set to 8. Timestamp A 64-bit unsigned integer field containing a timestamp. The value indicates the number of seconds since January 1, 1970, 00:00 UTC, by using a fixed point format. In this format, the integer number of seconds is contained in the first 48 bits of the field, and the remaining 16 bits indicate the number of 1/65536 fractions of a second.8.8.8.9. Status Values This document defines the following new Status values for use in Proxy Binding Acknowledgement message. These values are to be allocated from the same number space, as defined in Section 6.1.8 [RFC-3775]. Status values less than 128 indicate that the Proxy Binding Update request was accepted by the local mobility anchor. Status values greater than 128 indicate that the Proxy Binding Update was rejected by the local mobility anchor.PROXY_REG_NOT_ENABLED: Proxy Registration not enabled for the mobile node. MAG_NOT_AUTHORIZED_FOR_PROXY_REG: Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page64]68] Internet-Draft Proxy Mobile IPv6December 2007February 2008 PROXY_REG_NOT_ENABLED: Proxy registration not enabled for the mobile node MAG_NOT_AUTHORIZED_FOR_PROXY_REG: The mobile access gateway is not authorized to send proxybinding. updates.binding registrations NOT_AUTHORIZED_FOR_HOME_NETWORK_PREFIX The mobile node is not authorized for the requesting home networkprefix.prefix TIMESTAMP_MISMATCH: Invalid timestamp valuein the received Proxy Binding Update message(the clocks are out ofsync).sync) TIMESTAMP_LOWER_THAN_PREV_ACCEPTED: The timestamp valuein the received Proxy Binding Update messageis lower than the previously acceptedvalue.value MISSING_HOME_NETWORK_PREFIX_OPTION Missingmobile nodehome network prefixoption.option MISSING_MN_IDENTIFIER_OPTION: Missing mobile node identifierin the Proxy Binding Update message.option MISSING_HANDOFF_INDICATOR_OPTION Missing handoff indicator option MISSING_ACCESS_TECH_TYPE_OPTION Missingmobile node'saccess technology typein the Proxy Binding Update message.option Additionally, the following Status values defined in [RFC-3775] can Gundavelli (Editor), et al. Expires August 6, 2008 [Page 69] Internet-Draft Proxy Mobile IPv6 February 2008 also be used in Proxy Binding Acknowledgement message. 0 Proxy Binding Update accepted 128 Reason unspecified 129 Administratively prohibitedGundavelli, et al. Expires June 27, 2008 [Page 65] Internet-Draft Proxy Mobile IPv6 December 2007130 Insufficient resources 133 Not local mobility anchor for this mobile node 9. Protocol Configuration Variables The local mobility anchor MUST allow the following variables to be configured by the system management. MinDelayBeforeBCEDelete This variable specifies the amount of time in milliseconds the local mobility anchor MUST wait before it deletes a Binding Cache entry of a mobile node, upon receiving a Proxy Binding Update message from a mobile access gateway with a lifetime value of 0. During this wait time, if the local mobility anchor receives a Proxy Binding Update for the same mobility binding, with lifetime value greater than 0, then it must update the binding cache entry with the accepted binding values. By the end of this wait-time, if the local mobility anchor did not receive any valid Proxy Binding Update message for that mobility binding, it MUST delete the Binding Cache entry. This delay essentially ensures a mobile node's Binding Cache entry is not deleted too quickly and allows some time for the new mobile access gateway to complete the signaling for the mobile node. The default value for this variable is 10000 milliseconds.MinDelayBeforeNewBCEAssignMaxDelayBeforeNewBCEAssign This variable specifies the amount of time in milliseconds the local mobility anchor MUST wait for the de-registration message for an existing mobility session before it decides to create a new mobility session. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 70] Internet-Draft Proxy Mobile IPv6 February 2008 The default value for this variable is 500 milliseconds. TimestampValidityWindow This variable specifies the maximum amount of time difference in milliseconds between the timestamp in the received Proxy Binding Update message and the current time-of-day on the local mobility anchor, that is allowed by the local mobility anchor for the received message to be considered valid. The default value for this variable is 300 milliseconds. This variable MUST be adjusted to suit the deployments. The mobile access gateway MUST allow the following variables to be configured by the system management. EnableMAGLocalroutingGundavelli, et al. Expires June 27, 2008 [Page 66] Internet-Draft Proxy Mobile IPv6 December 2007This flag indicates whether or not the mobile access gateway is allowed to enable local routing of the traffic exchanged between a visiting mobile node and a correspondent node that is locally connected to one of the interfaces of the mobile access gateway. The correspondent node can be another visiting mobile node as well, or a local fixed node. The default value for this flag is set to "FALSE", indicating that the mobile access gateway MUST reverse tunnel all the traffic to the mobile node's local mobility anchor. When the value of this flag is set to "TRUE", the mobile access gateway MUST route the traffic locally. This aspect of local routing MAY be defined as policy on a per mobile basis and when present will take precedence over this flag.MinPBUReplyTime This variable specifies the amount of time in milliseconds the mobile access gateway SHOULD wait for the reply message for the Proxy Binding Update request that it sent to the local mobility anchor. The default value for this variable is 2000 milliseconds.10. IANA Considerations This document definesfivesix new Mobility HeaderOptions,options, the Home Network Prefix option, Handoff Indicator option, Access Technology Type option, Interface Identifier option, Link-local Address option and Timestamp option. These options are described inSections 8.3, 8.4, 8.5, 8.6 and 8.7 respectively.Section 8. The Type value for these options needs to be assigned from the same numbering space as allocated for the other mobility options, as defined in [RFC-3775]. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 71] Internet-Draft Proxy Mobile IPv6 February 2008 TheMobility Header Option,Access Technology Type option defined in Section8.48.5 of this document introduces a new Access Technology type numbering space, where the values from 0 to 5 have been reserved by this document. Approval of new Access Technology type numbers are to be made through IANA Expert Review. This document also defines new Binding Acknowledgement status values as described in Section8.8.8.9. The status values MUST be assigned from the same number space used for Binding Acknowledgement status values, as defined in [RFC-3775]. The allocated values for each of these status valuesMUST be greater than 128. Gundavelli, et al. Expires June 27, 2008 [Page 67] Internet-Draft Proxy Mobile IPv6 December 2007MUST be greater than 128. 11. Security Considerations The potential security threats against any network-based mobility management protocol are described in [RFC-4832]. This section explains how Proxy Mobile IPv6 protocol defends itself against those threats. Proxy Mobile IPv6 protocol requires the signaling messages, Proxy Binding Update and Proxy Binding Acknowledgement, exchanged between the mobile access gateway and the local mobility anchor to be protected using IPsec, using the established security association between them. This essentially eliminates the threats related to the impersonation of the mobile access gateway or the local mobility anchor. This specification allows a mobile access gateway to send binding registration messages on behalf of a mobile node. If proper authorization checks are not in place, a malicious node may be able to hijack a mobile node's session or may carry out a denial-of- service attack. To prevent this attack, this specification requires the local mobility anchor to allow only authorized mobile access gateways that are part of that Proxy Mobile IPv6 domain to send binding registration messages on behalf of a mobile node. To eliminate the threats on the interface between the mobile access gateway and the mobile node, this specification requires an established trust between the mobile access gateway and the mobile node and to authenticate and authorize the mobile node before it is allowed to access the network. Further, the established authentication mechanisms enabled on that access link will ensure that there is a secure binding between the mobile node's identity and its link-layer address. The mobile access gateway will definitively identify the mobile node from the packets that it receives on that access link. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 72] Internet-Draft Proxy Mobile IPv6 February 2008 To address the threat related to a compromised mobile access gateway, the local mobility anchor, before accepting a Proxy Binding Update message for a given mobile node, may ensure that the mobile node is definitively attached to the mobile access gateway that sent the proxy binding registration request. This may be accomplished by contacting a trusted entity which is able to track the mobile node's current point of attachment. However, the specific details of the actual mechanisms for achieving this is outside the scope of this document.Gundavelli, et al. Expires June 27, 2008 [Page 68] Internet-Draft Proxy Mobile IPv6 December 200712. Acknowledgements The authors would like to specially thank Julien Laganier, Christian Vogt, Pete McCann, Brian Haley, Ahmad Muhanna, JinHyeock Choi for their thorough review of this document. The authors would also like to thank Alex Petrescu, Alice Qinxia, Alper Yegin, Ashutosh Dutta, Behcet Sarikaya, Fred Templin, Genadi Velev, George Tsirtsis, Gerardo Giaretta, Henrik Levkowetz, Hesham Soliman, James Kempf, Jari Arkko, Jean-Michel Combes, John Zhao, Jong-Hyouk Lee, Jonne Soininen, Jouni Korhonen, Kalin Getov, Kilian Weniger, Marco Liebsch, Mohamed Khalil, Nishida Katsutoshi, Phil Roberts, Ryuji Wakikawa, Sangjin Jeong, Suresh Krishnan, Ved Kafle, Vidya Narayanan, Youn-Hee Han and many others for their passionate discussions in the working group mailing list on the topic of localized mobility management solutions. These discussions stimulated much of the thinking and shaped the draft to the current form. We acknowledge that ! The authors would also like to thank Ole Troan, Akiko Hattori, Parviz Yegani, Mark Grayson, Michael Hammer, Vojislav Vucetic, Jay Iyer and Tim Stammers for their input on this document. 13. References 13.1. Normative References [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC-2473] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 Specification", RFC 2473, December 1998. [RFC-3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M.Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 73] Internet-Draft Proxy Mobile IPv6 February 2008 [RFC-3775] Johnson, D., Perkins, C., Arkko, J., "Mobility Support in IPv6", RFC 3775, June 2004. [RFC-3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert, "Network Mobility (NEMO) Basic Support Protocol", RFC 3963, January 2005. [RFC-4283] Patel, A., Leung, K., Khalil, M., Akhtar, H., and K. Chowdhury, "Mobile Node Identifier Option for Mobile IPv6", RFC 4283, November 2005.Gundavelli, et al. Expires June 27, 2008 [Page 69] Internet-Draft Proxy Mobile IPv6 December 2007[RFC-4301] Kent, S. and Atkinson, R., "Security Architecture for the Internet Protocol", RFC 4301, December 2005. [RFC-4303] Kent, S. "IP Encapsulating Security Protocol (ESP)", RFC 4303, December 2005. [RFC-4861] Narten, T., Nordmark, E. and W. Simpson, Soliman, H., "Neighbor Discovery for IP Version 6 (IPv6)", RFC 4861, September 2007. 13.2. Informative References [RFC-1661] Simpson, W., Ed., "The Point-To-Point Protocol (PPP)", STD 51, RFC 1661, July 1994.[RFC-2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997.[RFC-3971] Arkko, J., Ed., Kempf, J., Sommerfeld, B., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005. [RFC-4140] Soliman, H., Castelluccia, C., El Malki, K., and L. Bellier, "Hierarchical Mobile IPv6 Mobility Management (HMIPv6)", RFC 4140, August 2005. [RFC-4306] Kaufman, C, et al, "Internet Key Exchange (IKEv2) Protocol", RFC 4306, December 2005. [RFC-4330] Mills, D., "Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI", RFC 2030, October 1996. [RFC-4372] Adrangi, F., Lior, A., Korhonen, J., and J. Loughney, "Chargeable User Identity", RFC 4372, January 2006. [RFC-4830] Kempf, J., Leung, K., Roberts, P., Nishida, K., Giaretta, G., Liebsch, M., "Problem Statement for Network-based Localized Mobility Management", September 2006. [RFC-4831] Kempf, J., Leung, K., Roberts, P., Nishida, K., Giaretta, Gundavelli (Editor), et al. Expires August 6, 2008 [Page 74] Internet-Draft Proxy Mobile IPv6 February 2008 G., Liebsch, M., "Goals for Network-based Localized Mobility Management", October 2006. [RFC-4832] Vogt, C., Kempf, J., "Security Threats to Network-Based Localized Mobility Management", September 2006. [RFC-4862] Thompson, S., Narten, T., Jinmei, T., "IPv6 Stateless Address Autoconfiguration", RFC 4862, September 2007.Gundavelli, et al. Expires June 27, 2008 [Page 70] Internet-Draft Proxy Mobile IPv6 December 2007[RFC-4941] Narten, T., Draves, R., Krishnan, S., "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 4941, September 2007.[RFC-5072] Varada, S., Haskin, D. and Allen, E., "IP version 6 over PPP", RFC 5072, September 2007.[ID-IPV4-PMIP6] Wakikawa, R. and Gundavelli, S., "IPv4 Support for Proxy Mobile IPv6", draft-ietf-netlmm-pmip6-ipv4-support-02.txt, November 2007. [ID-DNAV6] Kempf, J., et al "Detecting Network Attachment in IPv6 Networks (DNAv6)", draft-ietf-dna-protocol-06.txt, October 2006. Appendix A. Proxy Mobile IPv6 interactions with AAA Infrastructure Every mobile node that roams in a proxy Mobile IPv6 domain, would typically be identified by an identifier, MN-Identifier, and that identifier will have an associated policy profile that identifies the mobile node's home network prefix, permitted address configuration modes, roaming policy and other parameters that are essential for providing network-based mobility service. This information is typically configured in AAA. It is possible the home network prefix is dynamically allocated for the mobile node when it boots up for the first time in the network, or it could be a statically configured value on per mobile node basis. However, for all practical purposes, the network entities in the proxy Mobile IPv6 domain, while serving a mobile node will have access to this profile and these entities can query this information using RADIUS/DIAMETER protocols. Appendix B. Supporting Shared-Prefix Model using DHCPv6 This specification supports Per-MN-Prefix model. However, it is possible to support Shared-Prefix model under the following guidelines. The mobile node is allowed to use stateful address configuration Gundavelli (Editor), et al. Expires August 6, 2008 [Page 75] Internet-Draft Proxy Mobile IPv6 February 2008 using DHCPv6 for obtaining its address configuration. The mobile node is not allowed to use any of the stateless autoconfiguration techniques. The permitted address configuration models for the mobile node on the access link can be enforced by the mobile access gateway, by setting the relevant flags in the Router Advertisements, as per [RFC-4861].Gundavelli, et al. Expires June 27, 2008 [Page 71] Internet-Draft Proxy Mobile IPv6 December 2007The Home Network Prefix option that is sent by the mobile access gateway in the Proxy Binding Update message, must contain the128-bit host address128-bit host address that the mobile node obtained via DHCPv6. Routing state at the mobile access gateway: For all IPv6 traffic from the source MN-HoA::/128 to _ANY_DESTINATION_, route via tunnel0, next-hop LMAA, where tunnel0 is the MAG to LMA tunnel. Routing state at the local mobility anchor: For all IPv6 traffic to destination MN-HoA::/128, route via tunnel0, next-hop Proxy-CoA, where tunnel0 is the LMA to MAG tunnel. Appendix C. Routing State The following section explains the routing state for a mobile node on the mobile access gateway. This routing state reflects only one specific way of implementation and one MAY choose to implement it in other ways. The policy based route defined below acts as a traffic selection rule for routing a mobile node's traffic through a specific tunnel created between the mobile access gateway and thatthemobilenode obtained via DHCPv6. Routing state atnode's local mobility anchor and with the specific encapsulation mode, as negotiated. The below example identifies the routing state for two visiting mobileaccess gateway:nodes, MN1 and MN2 with their respective local mobility anchors LMA1 and LMA2. For allIPv6traffic from the mobile node, identified by the mobile node's MAC address, ingress interface or sourceMN-HoA::/128prefix (MN-HNP) to_ANY_DESTINATION_,_ANY_DESTINATION_ route via interface tunnel0, next-hopLMAA, where tunnel0 is the MAG to LMA tunnel. Routing state at the local mobility anchor: For allLMAA. Gundavelli (Editor), et al. Expires August 6, 2008 [Page 76] Internet-Draft Proxy Mobile IPv6traffic to destination MN-HoA::/128, route via tunnel0, next-hop Proxy-CoA, where tunnel0 is the LMA to MAG tunnel.February 2008 +==================================================================+ | Packet Source | Destination Address | Destination Interface | +==================================================================+ | MAC_Address_MN1, | _ANY_DESTINATION_ | Tunnel0 | | (IPv6 Prefix or |----------------------------------------------| | Input Interface) | Locally Connected | Tunnel0 | +------------------------------------------------------------------+ | MAC_Address_MN2, | _ANY_DESTINATION_ | Tunnel1 | + (IPv6 Prefix or -----------------------------------------------| | Input Interface | Locally Connected | direct | +------------------------------------------------------------------+ Figure 22: Example - Policy based Route Table +==================================================================+ | Interface | Source Address | Destination Address | Encapsulation | +==================================================================+ | Tunnel0 | Proxy-CoA | LMAA1 | IPv6-in-IPv6 | +------------------------------------------------------------------+ | Tunnel1 |IPv4-Proxy-CoA | IPv4-LMA2 | IPv6-in-IPv4 | +------------------------------------------------------------------+ Figure 23: Example - Tunnel Interface Table Authors' Addresses Sri Gundavelli Cisco 170 West Tasman Drive San Jose, CA 95134 USA Email: sgundave@cisco.com Kent Leung Cisco 170 West Tasman Drive San Jose, CA 95134 USA Email: kleung@cisco.com Gundavelli (Editor), et al. Expires August 6, 2008 [Page 77] Internet-Draft Proxy Mobile IPv6 February 2008 Vijay Devarapalli Azaire Networks 4800 Great America Pkwy Santa Clara, CA 95054 USA Email: vijay.devarapalli@azairenet.comGundavelli, et al. Expires June 27, 2008 [Page 72] Internet-Draft Proxy Mobile IPv6 December 2007Kuntal Chowdhury Starent Networks 30 International Place Tewksbury, MA Email: kchowdhury@starentnetworks.com Basavaraj Patil Nokia Siemens Networks 6000 Connection Drive Irving, TX 75039 USA Email: basavaraj.patil@nsn.comGundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page73]78] Internet-Draft Proxy Mobile IPv6December 2007February 2008 Full Copyright Statement Copyright (C) The IETF Trust(2007).(2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA).Gundavelli,Gundavelli (Editor), et al. ExpiresJune 27,August 6, 2008 [Page74]79] ----