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Versions: 00 01 02 03 04 05 06 RFC 6279

NetExt Working Group                                     M. Liebsch, Ed.
Internet-Draft                                                       NEC
Intended status: Informational                                  S. Jeong
Expires: September 15, 2011                                         ETRI
                                                                   Q. Wu
                                                                  Huawei
                                                          March 14, 2011


               PMIPv6 Localized Routing Problem Statement
                  draft-ietf-netext-pmip6-lr-ps-06.txt

Abstract

   Proxy Mobile IPv6 is the IETF standard for network-based mobility
   management.  In Proxy Mobile IPv6, mobile nodes are topologically
   anchored at a Local Mobility Anchor, which forwards all data for
   registered mobile nodes.  The setup and maintenance of localized
   routing, which allows forwarding of data packets between mobile nodes
   and correspondent nodes directly without involvement of the Local
   Mobility Anchor in forwarding, is not considered.  This document
   describes the problem space of localized routing in Proxy Mobile
   IPv6.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 15, 2011.

Copyright Notice

   Copyright (c) 2011 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



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   (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.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions and Terminology  . . . . . . . . . . . . . . . . .  4
   3.  Problem Statement for Localized Routing in PMIPv6  . . . . . .  5
     3.1.  General Observation  . . . . . . . . . . . . . . . . . . .  5
     3.2.  Use Cases Analysis . . . . . . . . . . . . . . . . . . . .  6
     3.3.  IPv4 Considerations  . . . . . . . . . . . . . . . . . . .  8
       3.3.1.  Localized Routing for Communication between IPv4
               Home Addresses . . . . . . . . . . . . . . . . . . . .  8
       3.3.2.  IPv4 Transport Network Considerations  . . . . . . . .  9
   4.  Functional Requirements for Localized Routing  . . . . . . . . 10
   5.  Roaming Considerations . . . . . . . . . . . . . . . . . . . . 11
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 15
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 16
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 16
   Appendix A.  Change Notes  . . . . . . . . . . . . . . . . . . . . 17
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19





















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1.  Introduction

   The IETF has specified Proxy Mobile IPv6 (PMIPv6) [RFC5213] as the
   base protocol for network-based localized mobility management
   (NetLMM).  The scope of the base protocol covers the set up and
   maintenance of a tunnel between an MN's Mobile Access Gateway (MAG)
   and its selected Local Mobility Anchor (LMA).  Data packets will
   always traverse the MN's MAG and its LMA, irrespective of the
   location of the MN's remote communication endpoint.  Even though an
   MN may be attached to the same or a different MAG as its
   Correspondent Node (CN) within the same provider domain, packets
   being associated with their communication will traverse the MN's and
   the CN's LMA.  [RFC5213] addresses the need to enable local routing
   of traffic between two nodes being attached to the same MAG, but does
   not specify the complete procedure to establish such localized
   routing state on the shared MAG.

   The NetLMM Extensions (NetExt) Working Group has an objective to
   design a solution for localized routing in PMIPv6.  This includes the
   specification of protocol messages and associated protocol operation
   between PMIPv6 components to support the setup of a direct routing
   path for data packets between the MN's and the CN's MAG.  As a result
   of localized routing, these packets will be forwarded between the two
   associated MAGs without traversing the MN's and the CN's LMA(s).  In
   case one or both nodes hand over to a different MAG, the localized
   routing protocol maintains the localized routing path.  Relevant
   protocol interfaces may include the interface between associated
   MAGs, between a MAG and an LMA as well as between LMAs.

   This document analyzes and discusses the problem space of using
   always the default route through two communicating mobile nodes'
   local mobility anchors.  Furthermore, the problem space of enabling
   localized routing in PMIPv6 is analyzed and described, while
   different communication and mobility scenarios are taken into
   account.
















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2.  Conventions and Terminology

   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 [RFC2119].

   This document uses the terminology of [RFC5213].  The following terms
   are used in the context of this problem statement:

   o  Mobile Node (MN): Mobile Node without IP mobility support, which
      is attached to a Mobile Access Gateway (MAG) and registered with a
      Local Mobility Anchor (LMA) according to the PMIPv6 specification
      [RFC5213].

   o  Correspondent Node (CN): Correspondent Node according to its
      definition in [RFC3775] with or without IP mobility support.  The
      CN represents the communication peer of an MN, which is attached
      to a MAG and registered with an LMA according to the PMIPv6
      specification.

   o  Localized Routing: Result of signaling to set up routing states on
      relevant network entities to allow forwarding of data packets
      between an MN and a CN, which are attached to MAGs sharing the
      same provider domain, without intervention of the MN's LMA and the
      CN's LMA in data forwarding.

   o  Localized Routing States: Information for localized routing on
      relevant forwarding entities on the optimized data path between an
      MN and a CN.  Such information includes route entries and tunnel
      endpoints and may include further information about the MN and the
      CN, such as the communicating nodes' Mobile Node Identifier and
      their assigned Home Network Prefix.

   o  Provider Domain: A network domain in which network components are
      administered by a single authority, e.g. the mobile operator.
















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3.  Problem Statement for Localized Routing in PMIPv6

3.1.  General Observation

   The Mobile IPv6 (MIPv6) protocol [RFC3775] has built-in mechanisms
   for direct communication between an MN and a CN.  Mechanisms for
   route optimization in MIPv6 cannot be directly applied in PMIPv6.
   Following the paradigm of PMIPv6, MNs are not involved in mobility
   signaling, hence cannot perform signaling to set up localized routes.
   Instead, the solution for localized routing must consider functions
   in the network to find out whether or not a localized route is to be
   used and then control the setup and maintenance of localized routing
   states accordingly without any assistance from the MN and the CN.  In
   case of communication between two nodes, which are attached to the
   PMIPv6 network infrastructure and each node is registered with an
   LMA, data packets between these two nodes will always traverse the
   responsible LMA(s).  At least some deployment would benefit from
   having such communication localized, rather than traverse the core
   network to the LMA(s).  In the context of this document, such
   localized communication comprises offloading traffic from LMAs and
   establish an optimized forwarding path between the two communication
   endpoints.

   Localized routing is understood in [RFC5213] as optimization of
   traffic between an MN and a CN that are attached to an access link
   connected to a same MAG.  In such case, the MAG forwards traffic
   directly between the MN and the CN, assuming the MAG is enabled to
   support this feature (setting of the EnableMAGLocalRouting flag on
   the MAG) and the MN's LMA enforces this optimization.  [RFC5213] does
   not specify how an LMA can enforce optimization for such local
   communication.  Maintaining local forwarding between the MN and the
   regular IPv6 CN gets more complex in case the MN performs a handover
   to a different MAG.  Such use case is not considered in the
   specification and out of scope of this problem statement.  This
   document focuses on use cases, where both nodes, the MN and the CN,
   are within a PMIPv6 network and served by an LMA in a domain of LMAs.

   Localized routing is relevant at least for the following two reasons:
   First, by limiting the communication to the access nodes, the data
   traffic traversing the MAG - LMA path (network) can be reduced.  This
   is significant considering that the transport network between the
   access and the core is often the bottleneck in terms of costs and
   performance.  Second, there may be performance benefits for data
   flows between the MN and the CN in terms of delay and packet loss,
   especially when the MN and the CN are attached to the same MAG and
   the LMA is topologically far away from that MAG.  Even when the MN
   and the CN are attached to different MAGs, there could be benefit in
   limiting the communication to the access network only, rather than



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   traversing the transport network to the LMA.  Furthermore, offloading
   traffic from the LMA by means of localized routing can improve
   scalability of the LMA, as it represents a bottleneck for traffic
   being forwarded by many MAGs.  Hence, providing the necessary
   protocol specification to enable localized routing in PMIPv6 is
   strongly recommended.

3.2.  Use Cases Analysis

   This problem statement focuses on local communication between PMIPv6
   managed nodes, which attach to MAGs sharing the same provider domain.
   The following list analyzes different use cases, which consider the
   existence of multiple LMAs.  Figure 1 depicts a PMIPv6-based network
   with two mobility anchors.  According to [RFC5213], the MN moves in
   the PMIPv6 domain being built by its LMA and MAG.  The same applies
   to the CN, which moves in the PMIPv6 domain built by the CN's LMA and
   MAG.  The analysis takes no assumption on whether the MN and the CN
   share the same PMIPv6 domain or not.


                              Internet Backbone
                             :                  :
                             +------------------+
                             |                  |
                          +----+              +----+
                          |LMA1|              |LMA2|
                          +----+              +----+
                             |                  |
                             |                  |
                        +----+------------------+----+
                        |                            |
                     +----+                       +----+
                     |MAG1|                       |MAG2|
                     +----+                       +----+
                     :    :                          :
                   +---+ +---+                     +---+
                   |MN | |CN1|                     |CN2|
                   +---+ +---+                     +---+


     Figure 1: Reference architecture for localized routing in PMIPv6

   All use cases A assume that both the MN and the CN are registered
   with an LMA according to the PMIPv6 protocol.  Whereas MAG1 is always
   considered as the MN's current Proxy Care-of Address, the CN can be
   either connected to the same or a different MAG or LMA as the MN.
   Accordingly, these topological differences are denoted as follows:




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   A[number of MAGs][number of LMAs]

   A11:  MN and CN (CN1) connect to the same MAG (MAG1) and are
      registered with the same LMA (LMA).  The common MAG may forward
      data packets between the MN and the CN directly without forwarding
      any packet to the LMA.  [RFC5213] addresses this use case, but
      does not specify the complete procedure to establish such
      localized routing state on the shared MAG.

   A12:  MN and CN (CN1) connect to the same MAG (MAG1) and are
      registered with different LMAs (LMA1 and LMA2).  The common MAG
      may forward data packets between the MN and the CN directly
      without forwarding any packet to the LMAs.  Following the policy
      of [RFC5213] and enforcement of the setup of a localized
      forwarding path, potential problems exist in case LMA1 and LMA2
      differ in their policy to control the MAG.

   A21:  The CN (CN2) connects to a different MAG (MAG2) as the MN
      (MAG1), but MN and CN are registered with the same LMA (LMA1).
      The result of localized routing should be the existence of routing
      information at MAG1 and MAG2, which allows direct forwarding of
      packets between the MN's MAG1 and the CN's MAG2.  As LMA1 is the
      common anchor for MN and CN and maintains location information for
      both nodes, no major race condition and instability in updating
      the states for localized routing is expected.

   A22:  The CN (CN2) connects to a different MAG (MAG2) and a different
      LMA (LMA2) as the MN (MAG1, LMA1).  The result of localized
      routing should be the existence of routing information at MAG1 and
      MAG2, which allows direct forwarding of packets between the MN's
      MAG1 and the CN's MAG2.  As the location information of the CN and
      the MN is maintained at different LMAs, both LMAs need to be
      involved in the procedure to set up localized routing.  In case of
      a handover of the MN and/or the CN to a different MAG, not
      synchronized control of updating the states for localized routing
      may result in race conditions, superfluous signaling and packet
      loss.

   The following list summarizes general problems with setting up and
   maintaining localized routing between an MN and a CN.  In the context
   of this problem statement, the MN and the CN are always assumed to be
   registered at an LMA according to the PMIPv6 protocol [RFC5213].

   o  MNs do not participate in mobility management, hence cannot
      perform binding registration at a CN on their own.  Rather
      entities in the network infrastructure must take over the role of
      MNs to set up and maintain a direct route.  Accordingly, a
      solution for localized routing in PMIPv6 must specify protocol



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      operation between relevant network components, such as between a
      MAG and an LMA, to enable localized routing for data traffic
      without traversing the MNs' LMA(s).

   o  In case the MN and the CN are both registered with different LMAs
      according to the PMIPv6 protocol, relevant information for the set
      up of a localized routing path, such as the current MAG of the MN
      and the CN, is distributed between these LMAs.  This may
      complicate the setup and stable maintenance of states enabling
      localized routing.

   o  In case localized routing between an MN and a CN has been
      successfully set up and both nodes move and attach to a new access
      router simultaneously, signaling the new location and maintenance
      of states for localized routing at relevant routers may run into a
      race condition situation.  This can happen in case coordination of
      signaling for localized routing and provisioning of relevant state
      information is distributed between different network entities,
      e.g. different LMAs.  In such case, as a result of MN's handover,
      updated information about the MN's location may arrive at the CN's
      previous MAG while CN moved already to a new MAG.  The same
      applies to the other direction, where the system may update MN's
      previous MAG about CN's new location while the MN has moved to a
      new MAG in the meantime.  The protocol solution must deal with
      such exceptional handover cases efficiently to avoid or resolve
      such problem.

3.3.  IPv4 Considerations

   According to [RFC5844], the basic configuration requirements for
   supporting IPv4 in PMIPv6 are that LMAs and MAGs are both IPv4 and
   IPv6 enabled.  Also, LMAs and MAGs must have a globally unique IPv6
   address configured, irrespective of enabled support for IPv6 routing
   between these components.  This requirement should also apply to
   configuration requirements of localized routing.

   Additional issues emerge when localized routing is considered for
   PMIPv6 with IPv4 support.  These can be classified into two general
   groups, which are issues with localized routing between an MN's and a
   CN's IPv4 Home Addresses or transport plane issues.  The following
   subsections analyze these two groups.

3.3.1.  Localized Routing for Communication between IPv4 Home Addresses

   In case an LMA and a MAG hold a registration to support IPv4 Home
   Address mobility for an MN, the MAG and the LMA must support
   appropriate encapsulation of IPv4 packets.  To enable localized
   routing, the MN's MAG must encapsulate and forward routing path



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   optimized packets to the CN's MAG and needs to ensure, that the
   chosen encapsulation mode is supported by the correspondent MAG.
   Incompatibility in a selected encapsulation mode causes failure in
   setting up a localized route.

   When localized routing is used for IPv4 traffic, the conceptual data
   structures on associated MAGs must be augmented with appropriate
   parameters for forwarding localized traffic.  MAGs may need to
   maintain a routing state for each MN-CN-pair and make routing
   decisions for uplink traffic based on the packets' complete IPv4
   source and destination address.  Hence, conceptual data structures to
   handle states for localized routes need to comprise this address
   tuple for unique identification.

   As a known constraint, IPv4 addresses of two nodes, which hold
   addresses from a private address space, may overlap.  To uniquely
   identify both nodes, the IPv4 address of the MN and the CN must not
   overlap.  To cope with overlapping address spaces, the localized
   routing solution could use additional mechanisms to tag and uniquely
   identify the MN and the CN.

3.3.2.  IPv4 Transport Network Considerations

   The transport network between LMA and MAG may be based on IPv6 or
   IPv4.  Deployments may ensure that the same transport mechanism
   (i.e., IPv6 or IPv4) is used for operational consistency.  Similar to
   the encapsulation requirement stated in the previous section, the IP
   version used for localized routing is also assumed, by configuration,
   to be consistent across all MAGs within the associated provider
   domain.  The design of optional mechanisms for negotiating the IP
   version to use as well as the encapsulation mode to use are outside
   the scope of the NetExt WG's solution for localized routing.



















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4.  Functional Requirements for Localized Routing

   Several tasks need to be performed by the network infrastructure
   components before relevant information for such direct communication
   is discovered and associated states for localized routing can be set
   up.  The following list summarizes some key functions, which need to
   be performed by the PMIPv6 enabled network infrastructure to
   substitute mobile nodes in setting up a direct route.

   o  Detection of the possibility to perform localized routing.  This
      function includes looking at data packets' source and destination
      address.

   o  Initiation of a procedure, which sets up a localized routing path.

   o  Discovery of stateful entities (i.e. the LMA(s) and/or the
      MAG(s)), which maintain and can provide relevant information
      needed to set up a localized routing path.  Such information may
      include the routable address of an LMA or MAG, where one or both
      mobile nodes are connected to and registered with.

   o  Control in setting up and maintaining (e.g. during handover) the
      localized routing path.  Control is also needed to terminate the
      use of a localized routing path and to delete associated states,
      whereas a trigger for the termination may come from a non-PMIPv6
      related component.

   o  Enforcement of administrative policy rules to localized routing.
      Such policies allow operators to have further control on the set
      up of a localized route and enable the possibility to disallow
      localized routing, for example to ensure that traffic traverses
      charging related functions on the LMA.



















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5.  Roaming Considerations

   Figure 2 shows PMIPv6 roaming cases where PMIPv6 components (e.g.,
   LMAs, MAGs) tied by MN and CN may be distributed between different
   provider domains (i.e., domain A, B, C) and MN and/or CN moves from
   one provider domain to another one.  In order to support localized
   routing when roaming occurs, it is required that MAGs to which MN and
   CN connect are within the same provider domain and each MAG has a
   security relationship with the corresponding LMA which maintains the
   registration of the MN or the CN, respectively.

   According to the roaming model as depicted in Figure 2, MN's PMIPv6
   domain is characterized by its MAG (MAG1/MAG1') and its LMA (LMA1),
   whereas CN's PMIPv6 domain is characterized by CN's MAG (MAG2/MAG2')
   and its LMA (LMA2/LMA2').  A solution for localized routing cannot
   take any assumption about whether or not MN and CN share the same
   PMIPv6 domain, hence MAG1/MAG1' may not share a security association
   with LMA2/LMA2' and MAG2/MAG2' may not share a security association
   with LMA1 respectively.

   It is not required that LMAs, which hold the registration for the MN
   and the CN respectively, are part of the same provider domain as the
   MAGs where MN and CN attach.  When MN's MAG and MN's LMA belong to
   different provider domains (A and C), localized routing is subject to
   policy governing the service level agreements between these domains.
   The same applies to the provider domains which provide CN's MAG and
   LMA.  Based on the above requirements, four PMIPv6 roaming and non-
   roaming cases can be taken into account.

   o  Case 1: MN's MAG (MAG1), CN's MAG (MAG2), MN's LMA (LMA1), CN's
      LMA (LMA2) are located in the same provider domain A.

   o  Case 2: MN's MAG (MAG1), CN's MAG (MAG2), MN's LMA (LMA1) are
      located in the same domain A while CN's LMA (LMA2') is located in
      provider domain B.

   o  Case 3: MN's MAG (MAG1'), CN's MAG (MAG2') are located in domain C
      while MN's LMA (LMA1) and CN's LMA (LMA2) are located in provider
      domain A.

   o  Case 4: MN's MAG (MAG1'), CN's MAG (MAG2') are located in provider
      domain C while MN's LMA (LMA1) is located in provider domain A,
      and CN's LMA (LMA2) is located in provider domain B.

   In these roaming cases, MN can be allowed to roam within its domain
   (e.g, MN's home domain in which MN's LMA is located) or over
   different domains (e.g., MN moves from its home domain to a visited
   domain).  During mobility, CN and MN should remain attached to MAGs



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   of the same provider domain to maintain efficient routing of traffic
   between their MAGs.


                                     |
           +-----+       +-----+     |      +-----+
           |LMA1 |       |LMA2 |     |      |LMA2'|
           +-----+       +-----+     |      +-----+
                                     |
                                     |
                                     |
                                     |
           +-----+       +-----+     |
           |MAG1 |       |MAG2 |     |
           +-----+       +-----+     |
                                     |
                                     |
                  Provider Domain A  |  Provider Domain B
       ------------------------------+-------------------------------
                             Provider Domain C


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


      Figure 2: PMIPv6 roaming cases considered for Localized Routing























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6.  Security Considerations

   A protocol solution for localized routing in a PMIPv6 network must
   counter unauthorized change of a routing path.  In particular, the
   control plane for localized routing must preclude blocking or
   hijacking of mobile nodes' traffic by malicious or compromised
   network components.  A security solution must support suitable
   mechanisms for authentication of control plane components of the
   localized routing functional architecture for both scenarios, roaming
   and non-roaming.  Any possibility for Internet hosts to interfere
   with the localized routing procedure in a malicious manner must be
   precluded.

   Since network entities rather than MNs and CNs perform signaling to
   set up localized routing, the MIPv6 return routability test [RFC3775]
   is not suitable to authenticate associated signaling messages in
   PMIPv6.  Solutions for localized routing in PMIPv6 need to mitigate
   or to provide sufficient defense against possible security threats.
   When PMIPv6 participants are administered within the same domain,
   infrastructure-based authorization mechanisms, such as IPsec, may be
   usable to protect signaling for localized routing.

   Existing security associations according to [RFC5213] can be re-used
   to protect signaling for localized routing on the interface between a
   MAG and an LMA.  In case a protocol solution for localized routing in
   PMIPv6 relies on protocol operation between MAGs, means for
   protection of signaling between these MAGs must be provided.  The
   same applies for signaling on a possible protocol interface between
   two LMAs of the same domain.






















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7.  IANA Considerations

   This document does not require any action from IANA.
















































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8.  Acknowledgments

   Many aspects of the problem space for route optimization in PMIPv6
   have been discussed in the context of a PMIPv6 Route Optimization
   Design Goals document, which has been submitted to the NetLMM WG in
   November 2007.  This group of contributors includes Sangjin Jeong,
   Christian Vogt, Ryuji Wakikawa, Marco Liebsch, Behcet Sarikaya,
   Shinta Sugimoto, Long Le, Alice Qinxia and Jaehwoon Lee. Many thanks
   to Rajeev Koodli for his comments about the structure and scope of
   this problem statement for the NetExt WG.

   This problem statement reflects the results of the discussion in the
   NetExt group.  Many thanks to Hidetoshi Yokota, Carlos Bernardos,
   Ashutosh Dutta, Sri Gundavelli, Mohana Jeyatharan, Jouni Korhonen,
   Glen Zorn, Dirk von Hugo, Frank Xia, Xiangsong Cui and Basavaraj
   Patil for their comments and support to improve the quality of the
   problem statement.


































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9.  References

9.1.  Normative References

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

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

   [RFC5844]  Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
              Mobile IPv6", RFC 5844, May 2010.

9.2.  Informative References

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


































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Appendix A.  Change Notes

   Changes in version 01:

   o  Removed text about potential issues with IPv4 address conflict
      from Section 3.3.1 (out of NetExt scope)

   o  Removed NAT issues from Section 3.3.2 (out of NetExt scope)

   o  Removed text about IP version and encapsulation mode negotiation
      from 3.3.2 (out of NetExt scope)

   Changes in version 02:

   o  Consistently refer to communication between MN and CN, not between
      two MNs

   o  Adopt text to the result of the roaming model discussion and refer
      to provider domain, not PMIPv6 domain

   o  Revision of Terms section according to comments

   o  Revision of text in Section 3.1 about network entities, which
      perform signaling for localized routing (clarification)

   o  Revision of text in Section 3.1 to clarify about localized routing
      benefits

   o  Revision of text in Section 3.2 to clarify about signaling race
      condition in multi-LMA case

   o  Add more text to Section 5 about the roaming model for localized
      routing, relevance of the PMIPv6 domain concept and associated
      issues with localized routing in roaming case

   o  Modified heading of Section 3.3.1 to avoid confusion with
      localized routing between IPv4 Proxy-CoAs

   Changes in version 03:

   o  Editorial revision according to received comments

   o  IPv4 support reference updated from draft to RFC status

   Changes in version 04:






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   o  Editorial revision according to received and agreed comments

   Changes in version 05:

   o  Editorial revision and clarification according to remaining
      comments received during WG last call

   Changes in version 06:

   o  Address AD comment to clarify 2nd paragraph of Section 3.1

   o  Include functional requirement about policy enforcement for
      localized routing in Section 4

   o  Refer to localized routing specific security threats in the first
      paragraph of Section 6



































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Authors' Addresses

   Marco Liebsch (editor)
   NEC Laboratories Europe
   NEC Europe Ltd.
   Kurfuersten-Anlage 36
   69115 Heidelberg,
   Germany

   Phone: +49 6221 4342146
   Email: liebsch@neclab.eu


   Sangjin Jeong
   ETRI
   138 Gajeongno, Yuseong
   Daejeon,   305-700
   Korea

   Phone: +82 42 860 1877
   Email: sjjeong@etri.re.kr


   Qin Wu
   Huawei Technologies,Co.,Ltd
   12F, Huihong Mansion,No.91,Baixia Rd.,
   Nanjing,   210001
   China

   Phone: +86 21 84565892
   Email: sunseawq@huawei.com




















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