One document matched: draft-muhanna-netlmm-multihoming-support-00.txt




NETLMM Working Group                                          A. Muhanna
Internet-Draft                                                 M. Khalil
Intended status: Standards Track                         Nortel Networks
Expires: May 14, 2008                                  November 11, 2007


         Proxy MIPv6 support for Mobile Nodes with Multihoming
            draft-muhanna-netlmm-multihoming-support-00.txt

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   Proxy Mobile IPv6 is a network-based mobility protocol which provides
   IP mobility for a regular IPv6 mobile node without the involvement of
   the IPv6 host.  Whenever a mobile node is attached to a PMIPv6 domain
   via a mobility access gateway, MAG, it appears to the mobile node as
   if it is attached to the same home link and thus the mobile node may
   think that it is not roaming away from home.  An issue has been
   raised with respect to the base PMIPv6 protocol support of a mobile
   node with multiple physical interfaces.  This issue has been



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   referenced as PMIPv6 support for multihoming mobile node.  This
   document describes the multihoming issue as it relates to PMIPv6 and
   provides an analysis to all scenarios that have been identified thus
   far.


Table of Contents

   1.  Conventions used in this document  . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Multihoming Scenarios  . . . . . . . . . . . . . . . . . . . .  4
     3.1.  Multihoming with a Single Prefix Per Interface . . . . . .  4
       3.1.1.  Inter-MAG Context Transfer Use . . . . . . . . . . . .  6
       3.1.2.  Helping AAA Infrastructure Use . . . . . . . . . . . .  6
       3.1.3.  MN-MAG Interaction via Access Network or L2
               Interface  . . . . . . . . . . . . . . . . . . . . . .  7
     3.2.  Multihoming with Single IP Address per Interface . . . . .  7
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     7.1.  Normative References . . . . . . . . . . . . . . . . . . .  9
     7.2.  Informative References . . . . . . . . . . . . . . . . . .  9
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  9
   Intellectual Property and Copyright Statements . . . . . . . . . . 11


























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1.  Conventions used in this document

   The keywords "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 [1].

   All the general mobility terminologies and abbreviations are to be
   interpreted as defined in IPv6 Mobility Support specification [RFC-
   3775] and Proxy Mobile IPv6 [PMIP6-Base].


2.  Introduction

   Proxy Mobile IPv6 [PMIP6-Base] is a network-based mobility protocol
   which provides IP mobility for a regular IPv6 mobile node without the
   involvement of the IPv6 host.  When the IPv6 host has a multiple
   interfaces which are connected simultaneoulsy, then the base PMIPv6
   protocol may not be able to offer mobility to such a mobile node
   host.  However, in the case that the mobile node has multiple
   interfaces where the mobile node does not require simultatneous
   binding over these multiple interfaces, then PMIPv6 base protocol
   should handle this case in a straight forward fashion.  In other
   words, in case of inter-technology handoff and when the mobile node
   have two different interfaces to access different technologies while
   the mobile node have use the simultaneous binding only in the case of
   inter-technology handoff, PMIPv6 base protocol may handle this case
   quite straight forward without.  However, PMIPv6 base protocol does
   not specify the mechanism of how the MAG acquire the needed
   information for enabling PMIPv6 support for multihoming as per its
   general case scenario.

   On the other hand, when the IPv6 host use multiple physical
   interfaces to simultaneously attach to the same PMIPv6 domain, base
   PMIPv6 protocol need further development to address such case and
   scenario.  These interfaces could be of the same or different types
   of accesses.  It is also possible that the mobile node may handoff
   between different interfaces of the same access type or different
   accesses.

   In the case when a mobile node is not capable of handling the same
   prefix across multiple interfaces, this document provides the
   analysis of how PMIPv6 based protocol will enable mobility for such a
   case.  The following two scenarios have been identified and to some
   extent discussed on the netlmm mailing list where the mobile node is
   required to use all of its available interfaces simultaneously to
   attach to the same PMIPv6 domain.





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   o  Multihoming with a single prefix per interface.

   o  Multihoming with single IP address per interface.



3.  Multihoming Scenarios

   Two multihoming scenarios have been identified as described in the
   introduction section.  This document provides an analysis of these
   scenarios as per the following sections.  In all of these scenarios
   and in addition to the regular PMIPv6 base protocol required
   information, more information specific to the interface ID, access
   technology type, and the handoff indication is necessary in order for
   PMIPv6 protocol to offer IP mobility support to a mobile node with
   multihoming.  In PMIPv6 domain, there are several means for the MAG
   to acquire these extra information as listed below:

   o  Availability of Inter-MAG Context Transfer.

   o  Use of Available AAA Infrastructure.

   o  Direct MN-MAG Interaction via Access Network or L2 Interface.


   Under each of the multihoming scenarios, this analysis will provide
   how the MAG may be able to use each of the above resources to enable
   PMIPv6 multihoming support as explained and discussed in the sections
   below.

3.1.  Multihoming with a Single Prefix Per Interface

   In this case, every single interface of the IPv6 mobile node is
   assigned a specific IPv6 prefix as shown below in Figure 1.  In the
   case the LMA does not receive any extra information in the P-BU to
   inform the LMA with the interface ID, the access type, or the handoff
   indicator, the LMA default behavior is to assign a new IPv6 prefix
   for each P-BU received for the same MN-ID but from a different MAG.













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                                              LMA Binding Cache
                                              =================
                                              MN1-if1 [prefix1] --> MAG1
                                              MN1-if2 [prefix2] --> MAG2
                                              MN2-if3 [prefix3] --> MAG1
                                              MN2-if4 [prefix4] --> MAG2

          if3      +------+
    +------------->|      |                                   +------+
    |         if1  | MAG1 |\         +=================+      |      |
    |     +------->|      | \      /                     \    |      |
    |     |        +------+  \    /  IPv6/IPv4 Transport  \   |  L   |
 [MN-2] [MN-1]                +--+        ......           +--|  M   |
    |     |  if2   +------+   /   \  IPv6/IPv4 Transport  /   |  A   |
    |     +------->|      |  /     \                     /    |      |
    |    if4       | MAG2 | /        +=================+      |      |
    +------------->|      |/                                  |      |
                   +------+                                   +------+


                   |<---------------- PMIPv6 Domain ---------------->|



   Figure 1: PMIPv6 Multihoming Support: A single prefix per interface.



   In the case when the Mobile node is able to attach simultaneously to
   separate MAGs using different interfaces as per figure 1, LMA will
   assign a separate prefix per interface.  LMA is able to route each
   prefix's traffic after encapsulation to the corresponding MAG which
   the MN is attached to using the proper interface.  If a mobile node,
   e.g.  MN2, attaches to adifferent MAG, e.g.  MAG2 using interface if4
   after it has been attached to MAG1 via if3, LMA will assign prefix4
   to MN2 binding and points the binding to MAG2.  When MN2 decides to
   move and attaches to a different MAG which belongs to the same PMIPv6
   domain as per figure 1, e.g.  MAG3 using interface if4, MAG3 includes
   if4 in the P-BU message.  When the LMA receives the P-BU from MAG3,
   LMA is able to identify that the MN is handing off over interface if4
   to MAG3 and will assign the same prefix4 to maintain session
   continuity.  In case the interface ID is not available to MAG3, MAG3
   Must be able to set the handoff indication field in the Access
   Technology Type option to a value which indicates active handoff.  If
   LMA has only one binding cache entry for the same mobile node ID,
   then the LMA would be able to allocate the same prefix and maintain
   session continuity.




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3.1.1.  Inter-MAG Context Transfer Use

   In the case inter-MAG context transfer is available to the target
   MAG, the target MAG must receive the interface ID which is the mobile
   node is handing over.  In this case, both the access technology type
   and the handoff indication will be available to the target MAG.  If
   the above mentioned information is available to the target MAG during
   the multihomed mobile node inter-MAG context transfer, the target MAG
   will be able to provide the interface ID, the access technology type,
   and be able to correctly set the handoff indication in the Access
   Technology Type option.  When the target MAG sends a P-BU with these
   information, LMA will always be able to definitely identify the
   mobile node binding cache entry which belongs to the P-BU received
   from the target MAG.

3.1.2.  Helping AAA Infrastructure Use

   The helping AAA infrastructure can be used to enable PMIPv6 support
   of multihoming according to the following conditions:

   o  During Inter MAG handoff, mobile node will perform access
      authentication using AAA infrastructure.

   o  If the MN is performing access authentication during an inter-MAG
      handoff, the MN SHOULD provide the AAA infrastructure (AAA server)
      with the interface ID that the mobile node is handing off from,
      i.e. the previous interface ID.

   o  If the MN is performing access authentication during an inter-MAG
      handoff, the MN SHOULD provide the AAA infrastructure (AAA server)
      with the interface ID that the mobile node is handing off from,
      i.e. the previous interface ID and in the case that the MN is
      handing over to a different interface ID, the mobile node SHOULD
      provide the AAA infrastructure with the target interface ID.

   o  During Access authentication, the target MAG SHOULD be able to
      receive the previous and the target interface ID during the mobile
      node access authentication or by requesting them directly from the
      AAA infrastructure.

   o  In the case that the target interface ID is different than the
      previous interface ID, the target MAG MUST include both the target
      and previous interface IDs in the P-BU in order for the LMA to be
      able to identify the exact MN binding cache entry.







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3.1.3.  MN-MAG Interaction via Access Network or L2 Interface

   In the case that neither inter-MAG context transfer is available nor
   the help of the AAA infrastructure during access authentication, a
   direct communication between the MN and the MAG is required in order
   to enable the PMIPv6 multihoming support.  In this case the MN MUST
   be able to communicate interface and handoff information to access
   network during mobile node handoff.  The following information need
   to be communicated from the MN to the MAG via access network or L2
   interface signaling.

   o  During Inter MAG handoff, the target MAG MUST be able to receive
      the mobile node target interface ID from the mobile node, e.g. via
      access network.

   o  In the case that the target interface ID is different from the
      previous interface ID during Inter-MAG handoff, the MAG MUST be
      able to receive both the target and previous interface IDs.

   o  The MAG should be able to receive a handoff indication and the
      access technology type.


   If all the above information are available to the MAG during the MN
   inter-MAG handoff, the target MAG MUST include all these information
   in the P-BU to aid the LMA in identifying the exact mobile node
   binding cache entry.  In this case, LMA is able to maintain session
   continuity as it is necessary.

3.2.  Multihoming with Single IP Address per Interface

   This scenario is a special case of the main scenario listed under
   section 3.1.  In this case the LMA assign a unique IP address for
   each interface and maintain separate binding cache entry per
   interface.  Eventually this scenario causes a multi-link subnet since
   the same prefix is advertised over multiple subnets.  This scenario
   assumes that the mobile node would configure a unique IP address per
   interface in the case of static IP address configuration or the MN
   will req=uest the IP address via Dynamic Host Control Protocol [RFC-
   3315].











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                                                LMA Binding Cache
                                                =================
                                        MN1-if1 [addr1:prefix1] --> MAG1
                                        MN1-if2 [addr2:prefix1] --> MAG2
                                        MN2-if3 [addr3:prefix2] --> MAG1
                                        MN2-if4 [addr4:prefix2] --> MAG2

            if3      +------+
      +------------->|      |                                   +------+
      |         if1  | MAG1 |\         +=================+      |      |
      |     +------->|      | \      /                     \    |      |
      |     |        +------+  \    /  IPv6/IPv4 Transport  \   |  L   |
   [MN-2] [MN-1]                +--+        ......           +--|  M   |
      |     |  if2   +------+   /   \  IPv6/IPv4 Transport  /   |  A   |
      |     +------->|      |  /     \                     /    |      |
      |    if4       | MAG2 | /        +=================+      |      |
      +------------->|      |/                                  |      |
                     +------+                                   +------+


                     |<---------------- PMIPv6 Domain ---------------->|



   Figure 2: PMIPv6 Multihoming Support: A single address per interface.



   In this scenario it is LMA local policy to assign different prefix
   per mobile node or use the same prefix for assigning IP addresses for
   multiple mobile nodes.  Figure 2 above assumes that the LMA assigns a
   single prefix per MN but different IP address for each interface.


4.  IANA Considerations

   This document does not require any IANA interaction.




5.  Security Considerations

   This document does not present any new security requirement on the
   top of the security requirements listed in [PMIPv6-Base}.  It only
   present an analysis of PMIPv6 support for multihoming mobile nodes
   when connected to the same PMIPv6 domain.




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6.  Acknowledgements

   The authors would like to thank their colleagues who are willing to
   provide comments on the content of this draft.




7.  References



7.1.  Normative References


   [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate
   Requirement Levels", BCP 14, RFC 2119, March 1997.

   [PMIP6-Base] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury,
   K., and B. Patil, "Proxy Mobile IPv6", draft-ietf-netlmm-proxymip6-05
   (work in progress), September 2007.

   [RFC-3775] Johnson, D., Perkins, C., Arkko, J., "Mobility Support in
   IPv6", RFC 3775, June 2004.

7.2.  Informative References



   [RFC-2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
   2131, March 1997.

   [RFC-3315] Dynamic Host Configuration Protocol for IPv6 (DHCPv6).  R.
   Droms,Ed., J. Bound, B. Volz, T. Lemon, C. Perkins, M. Carney.  July
   2003.


Authors' Addresses

   Ahmad Muhanna
   Nortel Networks
   2221 Lakeside Blvd.
   Richardson, TX  75082
   USA

   Phone: +1 (972) 685-1416
   Email: amuhanna@nortel.com




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   Mohamed Khalil
   Nortel Networks
   2221 Lakeside Blvd.
   Richardson, TX  75082
   USA

   Phone: +1 (972) 685-0564
   Email: mkhalil@nortel.com











































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