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Versions: (draft-giaretta-netlmm-mip-interactions) 00 01 02 03 04 05 06 07 RFC 6612

NETLMM Working Group                                    G. Giaretta, Ed.
Internet-Draft                                                  Qualcomm
Intended status: Informational                         November 15, 2008
Expires: May 19, 2009


  Interactions between PMIPv6 and MIPv6: scenarios and related issues
                 draft-ietf-netlmm-mip-interactions-01

Status of this Memo

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   This Internet-Draft will expire on May 19, 2009.

Abstract

   The scenarios where Proxy Mobile IPv6 (PMIPv6) and Mobile IPv6
   (MIPv6) protocols are both deployed in a network require some
   analysis and considerations.  This document describes all identified
   possible scenarios, which require an interaction between PMIPv6 and
   MIPv6 and discusses all issues related to these scenarios.  Solutions
   and reccomendations to enable these scenarios are also described.

Requirements Language

   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 [RFC2119].



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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Overview of the scenarios and related issues . . . . . . . . .  4
     3.1.  Issues related to scenario A . . . . . . . . . . . . . . .  9
     3.2.  Issues related to scenario B . . . . . . . . . . . . . . .  9
     3.3.  Issues related to scenario C . . . . . . . . . . . . . . . 10
   4.  Analysis of possible solutions . . . . . . . . . . . . . . . . 12
     4.1.  Solutions related to scenario A  . . . . . . . . . . . . . 12
     4.2.  Solutions related to scenario B  . . . . . . . . . . . . . 14
     4.3.  Solutions related to scenario C  . . . . . . . . . . . . . 14
       4.3.1.  Mobility from a PMIPv6 domain to a non-PMIPv6
               domain . . . . . . . . . . . . . . . . . . . . . . . . 15
       4.3.2.  Mobility from a non-PMIPv6 domain to a PMIPv6
               domain . . . . . . . . . . . . . . . . . . . . . . . . 16
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   6.  Additional Authors . . . . . . . . . . . . . . . . . . . . . . 17
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 18
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 18
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 18
   Intellectual Property and Copyright Statements . . . . . . . . . . 20



























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1.  Introduction

   Proxy Mobile IPv6 [RFC5213] is the network based protocol
   standardized by IETF.  In many deployment scenarios this protocol
   will be deployed together with MIPv6 [RFC3775], for example with
   PMIPv6 as local mobility protocol and MIPv6 as global mobility
   protocol.  While the usage of a local mobility protocol should not
   have implications of how global mobility is managed, since PMIPv6 is
   partially based on MIPv6 signaling and data structure, some
   considerations are needed to understand how the protocols interact
   and how the different scenarios can be enabled.

   Moreover, some SDOs are investigating complex scenarios where the
   mobility of some nodes are handled using Proxy Mobile IPv6, while
   other nodes use Mobile IPv6; or the mobility of a node is managed in
   turn by a host-based and a network-based mechanism.  This needs also
   to be analyzed as a possible deployment scenario.

   This document provides a taxonomy of all scenarios that require
   direct interaction between MIPv6 and PMIPv6.  Moreover, this document
   presents and identifies all known issues pertained to these scenarios
   and discusses possible means and mechanisms that are recommended to
   enable them.


2.  Terminology

   General mobility terminology can be found in [RFC3753].  The
   following acronyms are used in this document:

      MN-HoA: the home address of a mobile node in a Proxy Mobile IPv6
      domain.

      MN-HNP: the 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.  MN-
      HoA always belongs to this prefix.

      MIPv6-HoA: the Home Address the MN includes in MIPv6 binding
      update messages.  Based on the scenario, MIPv6-HoA and MN-HoA may
      be the same or different.

      MIPv6-CoA: the Care-of Address the MN includes in MIPv6 binding
      update messages.  Based on the scenario, MIPv6-HoA and MN-HoA may
      be the same or different.






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3.  Overview of the scenarios and related issues

   Several scenarios can be identified where Mobile IPv6 and Proxy
   Mobile IPv6 are deployed in the same network.  This document does not
   only focus on scenarios where the two protocols are used by the same
   mobile node to manage local and global mobility, but it investigates
   also more scenarios where the protocols are more tightly integrated
   or where there is a co-existence of nodes which do or do not
   implement Mobile IPv6.

   The following scenarios are identified:

   o  Scenario A - in this scenario Proxy Mobile IPv6 is used as a
      network based local mobility management protocol whereas Mobile
      IPv6 is used as a global mobility management protocol.  This
      interaction is very similar to the HMIPv6-MIPv6 interaction;
      Mobile IPv6 is used to manage mobility among different access
      networks, while the mobility within the access network is handled
      by Proxy Mobile IPv6.  The address managed by PMIPv6 (i.e. the MN-
      HoA based on PMIPv6 terminology) is registered as Care-of Address
      by the MN at the HA.  This means that the HA has a binding cache
      entry for MIPv6-HoA that points to the MN-HoA.





























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      The following figure illustrates this scenario.

                           +----+
                           | HA |  MIPv6-HoA -> MN-HoA
                           +----+
                             /\
                            /  \
             +-------------/----\--------------+
            (             /      \              ) Global Mobile IPv6
            (            /        \             ) Domain
             +----------/----------\-----------+
                       /            \
                    +----+         +----+
    MN-HoA -> MAG1  |LMA1|         |LMA2|
                    +----+         +----+
                     //\\             \\
               +----//--\\---+   +-----\\------+
              (    //    \\   ) (       \\      ) Local Mobility Network
              (   //      \\  ) (        \\     ) PMIPv6 domain
               +-//--------\\+   +--------\\---+
                //          \\             \\
               //            \\             \\
              //              \\             \\
           +----+           +----+         +----+
           |MAG1|           |MAG2|         |MAG3|
           +----+           +----+         +----+
             |                |              |
            [MN]

                                Figure 1 - Scenario A


   o  Scenario B - in this scenario some mobile nodes use Mobile IPv6 to
      manage their movements while others rely on a network-based
      mobility solution provided by the network.  There may be a common
      mobility anchor that acts as Mobile IPv6 Home Agent and Proxy
      Mobile IPv6 LMA, depending on the type of the node as depicted in
      the figure.  However, the LMA and HA can be also separated and
      this has no impacts to the mobility of the nodes.












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                                  +--------+
                                  | HA/LMA |
                                  +--------+

             +------+                              +------+
             | MAG1 |                              | MAG2 |
             +------+                              +------+

                        +-----------+
                        | IPv6 host |   ----------------->
                        +-----------+       movement
                     +----------+
                     | MIPv6 MN |  ----------------->
                     +----------+       movement

                                 Figure 2 - Scenario B


   o  Scenario C - in this scenario the mobile node is moving across
      different access networks, some of them supporting Proxy Mobile
      IPv6 and some others not supporting it.  Therefore the mobile node
      is roaming from an access network where the mobility is managed
      through a network-based solution to an access network where a
      host-based management (i.e.  Mobile IPv6) is needed.  This
      scenario may have different sub-scenarios depending on the
      relations between the Mobile IPv6 home network and the Proxy
      Mobile IPv6 domain.  The following figure illustrates an example
      of this scenario, where the MN is moving from an access network
      where PMIPv6 is supported (i.e.  MAG functionality is supported)
      to a network where PMIPv6 is not supported (i.e.  MAG
      functionality is not supported by the AR).  This implies that the
      home link of the MN is actually a PMIPv6 domain.  In this case the
      MIPv6-HoA is equal to the MN-HoA (i.e. the address managed by
      PMIPv6).

















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              MIPv6-HoA == MN-HoA -> MAG1
                    +------+
                    |HA/LMA|-----------------------+
                    +------+                       |
                      //\\                         |
             +-------//--\\--------+               |
            (       //    \\ PMIPv6 )              |
            (      //      \\ domain)       +--------------+
             +----//--------\\-----+       (   Non-PMIPv6   )
                 //          \\            (   domain       )
                //            \\            +--------------+
               //              \\                  |
            +----+           +----+              +----+
            |MAG1|           |MAG2|              | AR |
            +----+           +----+              +----+
              |                |                   |
             [MN]


                           Figure 3 - Scenario C


      In the above figure the non-PMIPv6 domain can actually be also a
      different PMIPv6 domain that handles a different MN_HoA.  The
      following figure illustrates this sub-case: the MIPv6-HoA is equal
      to the MN_HoA; however when the MN hands over to MAG3 it gets a
      different IP address (managed by LMA2 using PMIPv6) and registers
      it as a MIPv6 CoA.























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             MIPv6-HoA == MN-HoA -> MAG_1
                     +-------+
                     |HA/LMA1|-----------------------+
                     +-------+                       |
                       //\\                       +----+
              +-------//--\\--------+             |LMA2|
             (       //    \\  home  )            +----+
             (      //      \\ PMIPv6)       +------||------+
             (     //        \\domain)      (       ||visited)
              +---//----------\\----+       (       ||PMIPv6 )
                 //            \\           (       ||domain )
                //              \\           +------||------+
             +----+           +----+              +----+
             |MAG1|           |MAG2|              |MAG3|
             +----+           +----+              +----+
               |                |                   |
              [MN]

                               (a)

              MIPv6-HoA -> MN_CoA
                     +-------+
                     |HA/LMA1|-----------------------+
                     +-------+                       |
                       //\\                       +----+
              +-------//--\\--------+             |LMA2|  MN_CoA -> MAG3
             (       //    \\  home  )            +----+
             (      //      \\ PMIPv6)       +------||------+
             (     //        \\domain)      (       ||visited)
              +---//----------\\----+       (       ||PMIPv6 )
                 //            \\           (       ||domain )
                //              \\           +------||------+
             +----+           +----+              +----+
             |MAG1|           |MAG2|              |MAG3|
             +----+           +----+              +----+
               |                |                   |
                                                   [MN]

                                (b)


         Figure 4 - Scenario C with visited PMIPv6 domain


   Note that some of the scenarios can be combined.  For instance,
   scenario B can be combined with scenario A or scenario C.

   The following sections describe some possible issues for each



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   scenario.  Note that the issues are described based on current
   specification and does not assume any optimized solution for any
   scenario.  The specifications considered as a baseline for the
   analysis are the following: [RFC3775], [RFC4877] and [RFC5213].  For
   example, the collocation of HA and LMA are considered as the
   combination of HA according [RFC3775] and LMA according to [RFC5213],
   e.g. no combined binding caches are considered.  The analysis of the
   collocated HA and LMA would show what is the preferred behaviour for
   this entity.  The behaviour and respective recommendations are
   described in Section 4.3.

3.1.  Issues related to scenario A

   This scenarios is very similar to other hierarchical mobility
   schemes, including a HMIPv6-MIPv6 scheme.  This is the scenario
   referenced in [RFC4830].  No issues have been identified in this
   scenario.  Note that a race condition where the MN registers the CoA
   at the HA before the CoA is actually bound to the MAG at the LMA is
   not possible.  The reason is that per PMIPv6 specification the MAG
   does not forward any packets sent by the MN until the PMIPv6 tunnel
   is up, regardless the mechanism used for address allocation.

   Section 4.1 describes one message flow in case PMIPv6 is used as a
   local mobility protocol and MIPv6 is used as a global mobility
   protocol.

3.2.  Issues related to scenario B

   In this scenario there are two types of nodes in the access network:
   some nodes support Mobile IPv6 while some others do not.  The
   rationale behind such a scenario is that the nodes implementing
   Mobile IPv6 may prefer or be configured to manage their own mobility
   to achieve better performance, e.g. for inter-technology handovers.
   Obviously, nodes that do not implement MIPv6 must rely on the network
   to manage their mobility: therefore Proxy MIPv6 is used for those
   nodes.

   Based on the current PMIPv6 solution described in [RFC5213], in any
   link of the PMIPv6 domain the MAG emulates the mobile node's home
   link, advertising the home link prefix to the MN in a unicast Router
   Advertisement message.  This ensures that the IP address of the MN is
   still considered valid by the MN itself.  The home network prefix
   (and any other information needed to emulate the home link) is
   included in the mobile node's profile that is obtained by the MAG via
   context transfer or via a policy store.

   However, in case there are nodes that implement Mobile IPv6 and want
   to use this protocol, the network must offer MIPv6 service to them.



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   In such case the MAG should not emulate the home link.  Instead of
   advertising the HNP, the MAG should advertise the topologically
   correct local IP prefix, i.e. the prefix belonging to the MAG, so
   that the MN detects an IP movement, configures a new CoA and sends a
   MIPv6 Binding Update based on [RFC3775].

3.3.  Issues related to scenario C

   This section highlights some considerations that are applicable to
   scenario C and need to be evaluated when selecting the technical
   approach to be chosen.

   1.  HoA management and lookup key in the binding cache

       *  in MIPv6 [RFC3775] the lookup key in the Binding Cache is the
          Home Address of the MN.  In particular, based on the base
          specification [RFC3775], the MN does not include any
          identifier, such as the MN-ID [RFC4283], in the Binding Update
          message other than its Home Address.  As described in
          [RFC4877], the identifier of the MN is known by the Home Agent
          after the IKEv2 exchange, but this is not used in the MIPv6
          signaling, nor as a lookup key for the binding cache.  On the
          other hand, as specified in [RFC5213], a Proxy Binding Update
          contains the Home Prefix of the MN, the MN-ID and does not
          include the Home Address of the MN (since it may not be known
          by the MAG and consequently by the HA/LMA).  The lookup key in
          the binding cache of the LMA is either the home prefix or the
          MN-ID.  This implies that lookup keys for MIPv6 and PMIPv6
          registrations are different.  Because of that, when the MN
          moves from its home network (i.e. from the PMIPv6 domain) to
          the foreign link, the Binding Update sent by the MN is not
          identified by the HA as an update of the Proxy Binding Cache
          Entry containing the home prefix of the MN, but a new binding
          cache entry is created.  Therefore PMIPv6 and MIPv6 will
          always create two different binding cache entries in the HA/
          LMA which implies that the HA and LMA are logically separated.
          How to handle the presence of the two binding cache entries
          for the same MN is described in Section 4.3.

   2.  MIPv6 de-registration Binding Update deletes PMIPv6 binding cache
       entry

       *  When the mobile node moves from a MIPv6 foreign network to the
          PMIPv6 home domain, the MAG registers the mobile node at the
          LMA by sending a Proxy Binding Update.  Subsequently, the LMA
          updates the mobile node's binding cache entry with the MAG
          address and the MAG emulates the mobile node's home link.
          Upon detection of the home link, the mobile node will send a



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          de-registration Binding Update to its home agent.  It is
          necessary to make sure that the de-registration of the MIPv6
          BU does not change the PMIPv6 BCE just created by the MAG.

   3.  Race condition between Binding Update and Proxy Binding Update
       messages (Sequence Numbers and Timestamps)

       *  MIPv6 and PMIPv6 use different mechanisms for handling re-
          ordering of registration messages and they are sent by
          different entities.  Whereas Binding Update messages are
          ordered by a sequence numbers and sent by the mobile node,
          Proxy Binding Update messages are ordered by a timestamp
          option and sent by MAGs.Assuming the mobile node's MAG sends a
          Proxy Binding Update message (for refreshing the mobile node's
          BCE or because the mobile node has just done a handover to
          this MAG) and shortly thereafter the mobile node moves out of
          the PMIP home domain, where it configures a new MIPv6-CoA and
          sends a Binding Update message to its home agent.  If now the
          Proxy Binding Update message from the MAG is delayed so that
          it reaches the LMA after the Binding Update, the binding cache
          entry at the LMA would wrongly point to the MAG.  Without
          further measures, it is not clear if packets are forwarded to
          the mobile node or not and for this reason the behavior of the
          HA/LMA needs to be clarified in case there are two BCEs, one
          PMIPv6 and one MIPv6 BCE, for the same MN.

   4.  Use of wrong home agent or LMA after handover

       *  This issues can arise if multiple LMAs are deployed in the
          PMIP home domain.  If the mobile node moves from a MIPv6
          foreign network to the PMIP home domain, the MAG must send the
          Proxy Binding Update to the particular LMA that is co-located
          with the home agent which maintains the active binding cache
          entry of the mobile node.  If a different LMA is assigned to
          the MAG, the MN will not be on the home link but will still
          have MIPv6 active and this may be not desirable in some
          deployments.

       *  Similarly, if the mobile node moves from the PMIP home domain
          to a MIPv6 foreign network, the mobile node must send the
          Binding Update to the particular home agent that is co-located
          with the LMA which maintains the active proxy binding cache
          entry of the mobile node.  If the mobile node selects a
          different home agent, packets addressed to the mobile node's
          home address do not reach the mobile node.






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   5.  Threat of compromised MAG

       *  In MIPv6 base specification [RFC3775] there is a strong
          binding between the Home Address registered by the MN and the
          Security Association used to modify the corresponding binding
          cache entry.

       *  In PMIPv6 specification, the MAG sends proxy binding updates
          on behalf of a mobile node to update the binding cache entry
          that corresponds to the mobile node's home address.  Since the
          MAG sends the binding updates, PMIPv6 requires security
          associations between each MAG and the LMA.

       *  As described in [RFC4832], in PMIPv6 the MAG compromise or
          impersonation is an issue.  RFC4832, section 2.2, describes
          how a compromised MAG can harm the functionality of LMA, e.g.
          manipulating LMA's routing table (or binging cache).

       *  In this mixed scenario, both host-based and network-based
          security associations are used to update the same binding
          cache entry at the HA/LMA (but see the first bullet of this
          list, as the entry may not be the same).  Based on this
          consideration, the threat described in [RFC4832] is worse as
          it affects also hosts that are using the LMA/HA as MIPv6 HA
          and are not using PMIPv6


4.  Analysis of possible solutions

4.1.  Solutions related to scenario A

   As mentioned in Section 3.1, there are no significant issues in this
   scenario.

   Figures 5 and 6 show a scenario where a MN is moving from one PMIPv6
   domain to another, based on the scenario of Figure 1.  In Figure 5,
   the MN moves from an old MAG to MAG2 in the same PMIPv6 domain: this
   movement triggers a PBU to LMA1 and the updating of the binding cache
   at the LMA1; there is no MIPv6 signaling as the CoA_1 registered at
   the HA is the Home Address for the PMIPv6 session.  In Figure 6, the
   MN moves from MAG2 in the LMA1 PMIPv6 domain to MAG3 in a different
   PMIPv6 domain: this triggers the PMIPv6 signaling and the creation of
   a binding at the LMA2.  On the other hand, the local address of the
   MN is changed, as the LMA hss changed, and therefore the MN sends a
   MIPv6 Binding Update to the HA with the new CoA_2.






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    +----+            +------+            +------+       +----+
    | MN |            | MAG2 |            | LMA1 |       | HA |
    +----+            +------+            +------+       +----+
      |                  |                    |            |
      |                  |                    |   +-----------------+
      |                  |                    |   |  HoA -> CoA_1   |
      |                  |                    |   | binding present |
      |                  |                    |   +-----------------+
      |                  |                    |            |
      | CoA conf/confirm |  PBU(CoA_1,MAG_2)  |            |
      | <--------------->|  ----------------->|            |
      |                  |              +-----------------+|
      |                  |              | CoA_1 -> MAG_2  ||
      |                  |              | binding updated ||
      |                  |              +-----------------+|
      |                  |          PBA       |            |
      |                  |   <----------------|            |
      |                  |                    |            |

       Figure 5 - Local Mobility Message Flow


    +----+            +------+            +------+       +----+
    | MN |            | MAG3 |            | LMA2 |       | HA |
    +----+            +------+            +------+       +----+

      |   CoA config     |  PBU(CoA_2,MAG_3)  |             |
      |<---------------->|------------------->|             |
      |                  |              +-----------------+ |
      |                  |              | CoA_2 -> MAG_3  | |
      |                  |              | binding created | |
      |                  |              +-----------------+ |
      |                  |          PBA       |             |
      |                  |<-------------------|             |
      |                  |                    |             |
      |                  |  BU (HoA, CoA_2)   |             |
      |---------------------------------------------------->|
      |                  |                    |             |
      |                  |                    |     +-----------------+
      |                  |                    |     |  HoA -> CoA_2   |
      |                  |                    |     | binding updated |
      |                  |                    |     +-----------------+
      |                  | BA                 |             |
      |<----------------------------------------------------|

        Figure 6 - Global Mobility Message Flow





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4.2.  Solutions related to scenario B

   The solution for this scenario may depend on the access network being
   able to determine that a particular mobile node wants to use Mobile
   IPv6.  This would require a solution at the system level for the
   access network and is out of scope of this document.  Solutions that
   do not depend on the access network are out of the scope of this
   document.

4.3.  Solutions related to scenario C

   As described in Section 3.3, in this scenario the mobile node relies
   on Proxy Mobile IPv6 as long as it is in the Proxy Mobile IPv6
   domain.  The mobile node then uses Mobile IPv6 whenever it moves out
   of the PMIPv6 domain which basically implies that the MIPv6 home link
   is a PMIPv6 domain.

   Analyzing the issues described in Section 3.3, it is clear that most
   of them are applicable only to the case where there is a common BCE
   for the PMIPv6 registration and the MIPv6 registration.  The issue on
   how the two protocols identify the BCE is valid only in case we
   assume that a PMIPv6 message has any value for a MIPv6 BCE.  If the
   two different BCEs are considered completely independent, then the
   issues described in Section 3.3 are not valid.  For this reason, it
   is recommended that when the MIPv6 home link is implemented as a
   PMIPv6 domain, the HA/LMA implementation treats the two protocol as
   independent.

   More in details the following principles should be followed by the
   HA/LMA implementation:

   o  PMIPv6 signaling does not overwrite any MIPv6 BCE.  In particular,
      when a PMIPv6 binding cache entry is created for a MN which has
      previously created a MIPv6 BCE, the MIPv6 BCE of the UE is not
      overwritten and a new PMIPv6 BCE is created.

   o  The downlink packets in the case where both the MIPv6 BCE and
      PMIPv6 BCE exist are processed as follows:

   o

      1.  1) The MIPv6 BCE is processed first.  If the destination
          address of the received downlink packet matches the the BCE of
          the HA, the packet is forwarded by encapsulating it with the
          care-of-address contained in the BCE.

      2.  2) If the destination address does not match the MIPv6 BCE,
          the BCE created by PMIPv6 is applied and the packet are



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          encapsualted to the registered MAG.

   The following subsections provide a description of the procedures
   which will be followed by the MN and HA/LMA based on the above
   principles.  The analysis is performed in two different subsections,
   depending if the MN moves from a PMIPv6 domain to a non-PMIPv6 domain
   or vice versa.

4.3.1.  Mobility from a PMIPv6 domain to a non-PMIPv6 domain

   Let's assume the MN is attached to a PMIPv6 domain and there is a
   valid Proxy Binding Cache entry at the LMA.  Then the MN moves to a
   different access network and starts using MIPv6 (e.g. because PMIPv6
   is not supported).  The MN needs to bootstrap MIPv6 parameters and
   send a MIPv6 Binding Update in order to have service continuity.
   Therefore the following steps must be performed by the UE:

   o  HA/LMA address discovery: the MN needs to discover the IP address
      of the LMA which has a valid binding cache entry for its home
      network prefix.  This is described in Section 3.3 as issue 4.

   o  Security Association establishment: the MN needs to establish an
      IPsec Security Association with the HA/LMA as described in
      [RFC4877]

   o  HoA or home network prefix assignment: as part of the MIPv6
      bootstrapping procedure the HA assigns a MIPv6 HoA to the MN.
      This address must be the same the MN was using in the PMIPv6
      domain.

   Since all these steps must be performed by the MN before sending the
   Binding Update, they have an impact on the handover latency
   experienced by the MN.  For this reason it is recommended that the MN
   establishes the IPsec security association (and consequently is
   provided by the HA/LMA with a MIPv6-HoA) when it is still attached to
   the PMIPv6 domain.  This implies that the mobile node has Mobile IPv6
   stack active while in the PMIPv6 domain, but as long as it is
   attached to the same Proxy Mobile IPv6 domain, it will appear to the
   mobile node as if it is attached to the home link.

   In order to establish the security association with the HA/LMA, the
   MN needs to discover the IP address of the LMA/HA while in the PMIPv6
   domain.  This can be done either based on DNS or based on DHCPv6, as
   described in [RFC5026] and [boot-integrated].  The network should be
   configured so that the MN discovers or gets assigned the same HA/LMA
   that was serving as the LMA in the PMIPv6 domain.  Details of the
   exact procedure are out of scope of this document.




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   When the MN establishes the security association, it acquires a home
   address based on [RFC5026].  However, based on PMIPv6 operations, the
   LMA knows only the Home Network Prefix used by the MN and does not
   know the MN-HoA.For this reason, the MN must be configured to propose
   MN-HoA as the home address in the IKEv2 INTERNAL_IP6_ADDRESS
   attribute during the IKEv2 exchange with the HA/LMA.  Alternatively
   the HA/LMA can be configured to provide the entire Home Network
   Prefix via the MIP6_HOME_LINK attribute to the MN as specified in
   [RFC5026]; based on this Home Network Prefix the MN can configure a
   home address.  Note that the security association must be bound to
   the MN-HoA used in the PMIPv6 domain as per [RFC4877].  Note that the
   home network prefix is shared between the LMA and HA and this implies
   that there is an interaction between the LMA and the HA in order to
   assign a common home netowkr prefix when triggered by PMIPv6 and
   MIPv6 signaling

   When the MN hands over to an access network which does not support
   Proxy Mobile IPv6, it sends a Binding Update to the HA.  A MIPv6 BCE
   is created irrespective of the existing PMIPv6 BCE.  Packets matching
   the MIPv6 BCE are sent to the CoA present in the MIPv6 BCE.  The
   PMIPv6 BCE will expire in case the MAG does not send a refresh PBU.
   The refresh PBU is sent by the MAG in case the MN is multihomed and
   one of the interface is still attached on the MAG link.

4.3.2.  Mobility from a non-PMIPv6 domain to a PMIPv6 domain

   In this section it is assumed that the MN is in a non-PMIPv6 access
   network and it has bootstrapped MIPv6 operations based on [RFC5026];
   therefore there is valid binding cache for its MIPv6-HoA at the HA.
   Then the MN moves to a PMIPv6 domain which is configured to be the
   home link for the MIPv6-HoA the MN has been assigned.

   In order to provide session continuity, the MAG needs to send a PBU
   to the HA/LMA that was serving the MN.  The MAG needs to discover the
   HA/LMA; however the current version of [RFC5213] assumes that the LMA
   is assigned or discovered when the MN attaches to the MAG. the exact
   mechanism is not specified in [RFC5213].  A detailed description of
   the necessary procedure is out of the scope of this document.  Note
   that the MAG may also rely on static configuration or lower layer
   information provided by the MN in order to select the correct HA/LMA.

   The PBU sent by the MAG creates a PMIPv6 BCE for the MN which is
   independent of the MIPv6 BCE.  Traffic destined to the MIPv6-HoA is
   still forwarded to the CoA present in the MIPv6 BCE.  When the MN
   wants to use the HoA directly from the home link, it sends a de-
   registration message and at that point only the PMIPv6 BCE is
   present.




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5.  Security Considerations

   Scenarios A and B described in Section 3 do not introduce any
   security considerations in addition to those described in [pmipv6-
   draft] or [RFC3775].

   This document requires that the a home agent that also implements the
   PMIPv6 LMA functionality should allow both the mobile node and the
   authorized MAGs to modify the binding cache entries for the mobile
   node.  Note that the compromised MAG threat described in [RFC4832]
   applies also here.


6.  Additional Authors

   Chowdhury, Kuntal - kchowdhury@starentnetworks.com

   Hesham Soliman - Hesham@elevatemobile.com

   Vijay Devarapalli - vijay.devarapalli@azairenet.com

   Sri Gundavelli - sgundave@cisco.com

   Kilian Weniger - Kilian.Weniger@eu.panasonic.com

   Genadi Velev - Genadi.Velev@eu.panasonic.com

   Ahmad Muhanna - amuhanna@nortel.com

   George Tsirtsis - tsirtsis@googlemail.com

   Suresh Krishnan - suresh.krishnan@ericsson.com


7.  Acknowledgements

   This document is a merge of four different Internet Drafts:
   draft-weniger-netlmm-pmipv6-mipv6-issues-00,
   draft-devarapalli-netlmm-pmipv6-mipv6-01,
   draft-tsirtsis-logically-separate-lmaha-01and
   draft-giaretta-netlmm-mip-interactions-00.  Thanks to the authors and
   editors of those drafts.

   The authors would also like ot thank Jonne Soininen and Vidya
   Narayanan, NETLMM WG chairs, for their support.


8.  References



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8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3775]  Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
              in IPv6", RFC 3775, June 2004.

   [RFC4832]  Vogt, C. and J. Kempf, "Security Threats to Network-Based
              Localized Mobility Management (NETLMM)", April 2007.

   [RFC4877]  Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with
              IKEv2 and the Revised IPsec Architecture", 2005.

   [RFC5026]  Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6
              Bootstrapping in Split Scenario", RFC 5026, October 2007.

   [RFC5213]  Gundavelli, S., "Proxy Mobile IPv6", August 2008.

   [boot-integrated]
              Chowdhury, K., Ed., "MIP6-bootstrapping for the Integrated
              Scenario", 2007.

   [draft-tsirtsis]
              Tsirtsis, G., "Behavior of Collocated HA/LMA", April 2008,
              <http://www.ietf.org/internet-drafts/
              draft-tsirtsis-logically-separate-lmaha-01.txt>.

   [pmipv6-draft]
              Gundavelli, S., Ed., "Proxy Mobile IPv6", 2007, <http://
              www.ietf.org/internet-drafts/
              draft-ietf-netlmm-proxymip6-01.txt>.

8.2.  Informative References

   [RFC3753]  Manner, J. and M. Kojo, "Mobility Related Terminology",
              RFC 3753, June 2004.

   [RFC4283]  Patel, A., Leung, K., Khalil, M., Akhtar, H., and K.
              Chowdhury, "Mobile Node Identifier Option for Mobile IPv6
              (MIPv6)", RFC 4283, November 2005.

   [RFC4831]  Kempf, J., "Goals for Network-Based Localized Mobility
              Management (NETLMM)", RFC 4831, April 2007.







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Author's Address

   Gerardo Giaretta (editor)
   Qualcomm

   Email: gerardog@qualcomm.com













































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