





Internet Engineering Task Force (IETF)                  G. Giaretta, Ed.
Request for Comments: 6612                                      Qualcomm
Category: Informational                                         May 2012
ISSN: 2070-1721


Interactions between Proxy Mobile IPv6 (PMIPv6) and Mobile IPv6 (MIPv6):
                      Scenarios and Related Issues

Abstract

   The use of Proxy Mobile IPv6 (PMIPv6) and Mobile IPv6 (MIPv6) in the
   same network requires some care.  This document discusses scenarios
   where such mixed usage is appropriate and points out the need for
   interaction between the two mechanisms.  Solutions and
   recommendations to enable these scenarios are also described.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6612.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.




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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................3
   3. Overview of the Scenarios and Related Issues ....................4
      3.1. Issues Related to Scenario A.1 .............................8
      3.2. Issues Related to Scenario A.2 .............................8
      3.3. Issues Related to Scenario B ..............................10
   4. Analysis of Possible Solutions .................................11
      4.1. Solutions Related to Scenario A.1 .........................11
      4.2. Solutions Related to Scenario A.2 .........................13
           4.2.1. Mobility from a PMIPv6 Domain to a
                  Non-PMIPv6 Domain ..................................14
           4.2.2. Mobility from a Non-PMIPv6 Domain to a
                  PMIPv6 Domain ......................................15
      4.3. Solutions Related to Scenario B ...........................15
   5. Security Considerations ........................................16
   6. Contributors ...................................................16
   7. Acknowledgements ...............................................16
   8. References .....................................................17
      8.1. Normative References ......................................17
      8.2. Informative References ....................................17

1.  Introduction

   Proxy Mobile IPv6 (PMIPv6) [RFC5213] is a network-based IP mobility
   protocol standardized by the IETF.  In some deployment scenarios,
   this protocol will be deployed together with Mobile IPv6 (MIPv6)
   [RFC6275], 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 on 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.





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   Some standardization fora are also investigating more complex
   scenarios where the mobility of some nodes is 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 also needs to be analyzed as a possible deployment
   scenario.

   This document provides a taxonomy of the most common scenarios that
   require direct interaction between MIPv6 and PMIPv6.  The list is not
   meant to be exhaustive.  Moreover, this document presents and
   identifies most of the issues pertaining 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:

   o  AR (Access Router): first hop router

   o  BCE (Binding Cache Entry): an entry of the MIPv6 or PMIPv6 binding
      cache

   o  LMA (Local Mobility Anchor): the PMIPv6 mobility anchor as
      specified in [RFC5213]

   o  MAG (Mobility Access Gateway): the PMIPv6 client as specified in
      [RFC5213]

   o  MN-HoA: the Home Address (HoA) of a Mobile Node (MN) in a PMIPv6
      domain

   o  MN-HNP: the IPv6 prefix that is always present in the Router
      Advertisements that the MN receives when it is attached to any of
      the access links in that PMIPv6 domain (MN-HoA always belongs to
      this prefix.)

   o  MIPv6-HoA: the HoA the MN includes in MIPv6 Binding Update
      messages

   o  MIPv6-CoA: the Care-of Address the MN includes in MIPv6 Binding
      Update messages








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3.  Overview of the Scenarios and Related Issues

   Several scenarios can be identified where MIPv6 and PMIPv6 are
   deployed in the same network.  This document not only focuses on
   scenarios where the two protocols are used by the same MN to manage
   local and global mobility but also investigates more complex
   scenarios where the protocols are more tightly integrated or where
   there is a coexistence of nodes that do or do not implement MIPv6.

   In particular, the scenario space can be split into hierarchical
   deployments and alternative deployments of Mobile IP (MIP) and Proxy
   Mobile IP (PMIP).  Hierarchical deployments are scenarios where the
   two mobility protocols are used in the same network in a hierarchical
   manner for global and local mobility management.  Alternative
   deployments are scenarios where only one of the two protocols is used
   for mobility management of a given MN.

   The following hierarchical scenarios are identified:

   Scenario A.1: In this scenario, PMIPv6 is used as a network-based
   local mobility management protocol whereas MIPv6 is used as a global
   mobility management protocol.  This interaction is very similar to
   the interaction between Hierarchical Mobile IPv6 (HMIPv6) and MIPv6
   [RFC5380]; MIPv6 is used to manage mobility among different access
   networks, while the mobility within the access network is handled by
   PMIPv6.  The address managed by PMIPv6 (i.e., the MN-HoA) is
   registered as the Care-of Address by the MN at the Home Agent (HA).
   This means that the HA has a BCE 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.1

   Scenario A.2: In this scenario, the MN is moving across different
   access networks, some of them supporting PMIPv6 and some others not
   supporting it.  Therefore, the MN 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 MIPv6 home network and the PMIPv6 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 2: Scenario A.2

   In the scenario illustrated in Figure 2, the non-PMIPv6 domain can
   actually also be 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 3: Scenario A.2 with Visited PMIPv6 Domain

   The following alternative deployment has been identified:

   Scenario B: In this scenario, some MNs use MIPv6 to manage their
   movements while others rely on a network-based mobility solution
   provided by the network as they don't support Mobile IPv6.  There may



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   be a common mobility anchor that acts as MIPv6 Home Agent and PMIPv6
   LMA, depending on the type of the node as depicted in the figure.
   However, the LMA and HA can also be separated, and this has no impact
   on the mobility of the nodes.
                                     +--------+
                                     | HA/LMA |
                                     +--------+

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

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

                           Figure 4: Scenario B

   Note that some of the scenarios can be combined.  For instance,
   Scenario B can be combined with Scenario A.1 or Scenario A.2.

   The following sections describe some possible issues for each
   scenario.  Respective recommendations are described in Section 4.3.
   The specifications considered as a baseline for the analysis are the
   following: [RFC6275], [RFC4877], and [RFC5213].

3.1.  Issues Related to Scenario A.1

   This scenario is very similar to other hierarchical mobility schemes,
   including an HMIPv6-MIPv6 scheme.  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 the PMIPv6 specification
   [RFC5213], 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 A.2

   This section highlights some considerations that are applicable to
   scenario A.2.



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   1.  HoA management and lookup key in the binding cache

       *  In MIPv6 [RFC6275], the lookup key in the binding cache is the
          HoA of the MN.  In particular, the base specification
          [RFC6275] doesn't require the MN to include any identifier,
          such as the MN-ID [RFC4283], in the Binding Update message
          other than its HoA.  As described in [RFC4877], the identifier
          of the MN is known by the Home Agent after the Internet Key
          Exchange Protocol (IKEv2) exchange, but this is not used in
          the MIPv6 signaling or 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 HoA 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 BCE containing
          the home prefix of the MN, but a new binding cache entry is
          created.  Therefore, PMIPv6 and MIPv6 will always create two
          different BCEs in the HA/LMA, which implies that the HA and
          LMA are logically separated.  How to handle the presence of
          the two BCEs for the same MN is described in Section 4.2.

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

       *  When the MN moves from a MIPv6 foreign network to the PMIPv6
          home domain, the MAG registers the MN at the LMA by sending a
          Proxy Binding Update.  Subsequently, the LMA updates the MN's
          BCE with the MAG address and the MAG emulates the MN's home
          link.  Upon detection of the home link, the MN will send a
          de-registration Binding Update to its home agent.  It is
          necessary to make sure that the de-registration of the MIPv6
          Binding Update 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.  In MIPv6, Binding Update messages that
          are sent by the MN to the home agent are ordered by the
          sequence numbers.  The other side, in PMIPv6, Proxy Binding
          Update messages that are sent by the MAG to the LMA are



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          ordered by a timestamp option.  When the MN moves from one
          access where Mobile IP is used to another access when Proxy
          Mobile IP is used, delay in the mobility signaling sent may
          imply adverse situations.  For example, if the MN sends a
          Mobile IP Binding Update from access A before moving to access
          B and this Binding Update gets delayed (e.g., a refresh
          Binding Update), the Binding Update may reach the combined
          LMA/HA after the Proxy Binding Update sent by the MAG,
          re-directing packets to access A even after the MN has moved
          to access B.

   4.  Threat of compromised MAG

       *  In the MIPv6 base specification [RFC6275], there is a strong
          binding between the HoA registered by the MN and the Security
          Association (SA) used to modify the corresponding BCE.

       *  In the PMIPv6 specification [RFC5213], the MAG sends Proxy
          Binding Updates on behalf of a MN to update the BCE that
          corresponds to the MN's HoA.  Since the MAG sends the Binding
          Updates, PMIPv6 requires SAs between each MAG and the LMA.

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

       *  In this mixed scenario, both host-based and network-based SAs
          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 also affects hosts that
          are using the LMA/HA as MIPv6 HA and not using PMIPv6.

3.3.  Issues Related to Scenario B

   In this scenario, there are two types of nodes in the access network:
   some nodes support MIPv6 while some others do not.  The rationale
   behind such a scenario is that the nodes implementing MIPv6 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 MN'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



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   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 MN's profile that is obtained by the MAG via context
   transfer or via a policy store.

   However, in case there are nodes that implement MIPv6 and want to use
   this protocol, the network must offer MIPv6 service to them.  In such
   a case, the MAG should not emulate the home link.  Instead of
   advertising the MN-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 [RFC6275].

4.  Analysis of Possible Solutions

4.1.  Solutions Related to Scenario A.1

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

   Figures 5 and 6 show a scenario where an 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 HoA 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
   mobile node is changed, as the LMA has changed; 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 A.2

   As described in Section 3.2, in this scenario, the MN relies on
   PMIPv6 as long as it is in the PMIPv6 domain.  The MN then uses MIPv6
   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 3.2, 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.  Issue 1, on
   how the two protocols identify the BCE, is valid only in the case in
   which we assume that a PMIPv6 message has any value for a MIPv6 BCE.
   Also, Issues 2 and 3 are not applicable in the case in which
   different logical BCEs are used by the LMA and the HA.  For this
   reason, it is recommended that when the MIPv6 home link is
   implemented as a PMIPv6 domain, the HA/LMA implementation treat the
   two protocols as independent.

   In more detail, 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 BCE is created for an MN that has previously created
      a MIPv6 BCE, the MIPv6 BCE of the MN 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:

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

      2.  If the destination address does not match the MIPv6 BCE, the
          BCE created by PMIPv6 is applied, and the packets are
          encapsulated to the registered MAG.

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








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4.2.1.  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 BCE 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 User Equipment (UE):

   o  HA/LMA address discovery: the MN needs to discover the IP address
      of the LMA that has a valid BCE for its home network prefix.  This
      is described in Section 3.2 as Issue 4.

   o  SA 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 establish the IPsec SA (and, consequently, be provided by the HA/
   LMA with a MIPv6-HoA) when it is initialized.  This implies that the
   MN has MIPv6 stack active while in the PMIPv6 domain, but as long as
   it is attached to the same PMIPv6 domain, it will appear to the MN as
   if it is attached to the home link.

   In order to establish the SA 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 [RFC6611].  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.

   When the MN establishes the SA, it acquires an HoA 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 the MN-HoA as
   the HoA 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 an HoA.  Note that
   the SA must be bound to the MN-HoA used in the PMIPv6 domain as per



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   [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 network prefix when
   triggered by PMIPv6 and MIPv6 signaling.

   When the MN hands over to an access network that does not support
   Proxy Mobile IPv6, it sends a Binding Update to the HA.  The MN may
   set the R bit defined in the Network Mobility (NEMO) specification
   (implicit mode) [RFC3963] in order to indicate that the entire HNP is
   moved to the new CoA.  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 the case
   in which the MAG does not send a refresh PBU.

4.2.2.  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 (or HNP in
   case of NEMO) at the HA.  Then, the MN moves to a PMIPv6 domain that
   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, [RFC5213] assumes that the LMA is assigned to the
   MAG or discovered by the MAG 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 that is
   independent of the MIPv6 BCE.  Traffic destined to the MIPv6-HoA (or
   to the HNP in case the MN had set the flag R in the last BU) 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.

4.3.  Solutions Related to Scenario B

   The solution for this scenario depends on the access network being
   able to determine that a particular MN wants to use Mobile IPv6.
   This requires a solution at the system level for the access network
   and may require knowledge of the detailed configuration and software
   capabilities of every MN in the system.  These issues are out of the
   scope of this document.



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5.  Security Considerations

   Scenario A.1 does not introduce any new security issues in addition
   to those described in [RFC5213] or [RFC6275].

   For Scenario A.2, this document requires that the a home agent that
   also implements the PMIPv6 LMA functionality should allow both the MN
   and the authorized MAGs to modify the BCEs for the MN.  Note that the
   compromised MAG threat described in [RFC4832] also applies here in a
   more severe form as explained in Section 3.2.  Scenario B relies on
   the secure identification of MNs and their capabilities so that the
   right service can be provided for the right MNs.  For instance, a
   malicious MN should not get the HoA of some other node assigned to
   it, and a MN that desires to employ its own mobility management
   should be able to do so.  The ability to identify nodes is already a
   requirement in [RFC5213], but Scenario B adds a requirement on
   identification of node capabilities.

6.  Contributors

   Kuntal Chowdhury - kuntal@hotmail.com

   Vijay Devarapalli - vijay.devarapalli@azairenet.com

   Sri Gundavelli - sgundave@cisco.com

   Suresh Krishnan - suresh.krishnan@ericsson.com

   Ahmad Muhanna - amuhanna@nortel.com

   Hesham Soliman - Hesham@elevatemobile.com

   George Tsirtsis - tsirtsis@googlemail.com

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

   Kilian Weniger - Kilian.Weniger@googlemail.com

7.  Acknowledgements

   This document is a merge of four different documents: "Proxy Mobile
   IPv6 and Mobile IPv6 interworking issues" (April 2007), "Proxy Mobile
   IPv6 and Mobile IPv6 interworking" (April 2007), "Behavior of
   Collocated HA/LMA" (October 2008), and "Interactions between PMIPv6
   and MIPv6: scenarios and related issues" (November 2007).  Thanks to
   the authors and editors of those documents.





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

8.  References

8.1.  Normative References

   [RFC3963]  Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
              Thubert, "Network Mobility (NEMO) Basic Support Protocol",
              RFC 3963, January 2005.

   [RFC4832]  Vogt, C. and J. Kempf, "Security Threats to Network-Based
              Localized Mobility Management (NETLMM)", RFC 4832,
              April 2007.

   [RFC4877]  Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with
              IKEv2 and the Revised IPsec Architecture", RFC 4877,
              April 2007.

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

   [RFC5213]  Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
              and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.

   [RFC5380]  Soliman, H., Castelluccia, C., ElMalki, K., and L.
              Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
              Management", RFC 5380, October 2008.

   [RFC6275]  Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
              in IPv6", RFC 6275, July 2011.

   [RFC6611]  Chowdhury, K., Ed. and A. Yegin, "Mobile IPv6 (MIPv6)
              Bootstrapping for the Integrated Scenario", RFC 6611,
              May 2012.

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.







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Author's Address

   Gerardo Giaretta (editor)
   Qualcomm

   EMail: gerardog@qualcomm.com













































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