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Framework for Mobility Management Protocol
draft-chan-dmm-framework-00

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This is an older version of an Internet-Draft whose latest revision state is "Expired".
Authors Anthony Chan , Pierrick Seite , Kostas Pentikousis
Last updated 2013-02-18
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draft-chan-dmm-framework-00
Network Working Group                                            H. Chan
Internet-Draft                                       Huawei Technologies
Intended status: Informational                                  P. Seite
Expires: August 23, 2013                         France Telecom - Orange
                                                          K. Pentikousis
                                                     Huawei Technologies
                                                       February 19, 2013

               Framework for Mobility Management Protocol
                      draft-chan-dmm-framework-00

Abstract

   This document introduces a framework for mobility management
   protocols in terms of their key abstracted logical functions.  The
   framework is capable of presenting a unified view, reducing the
   clutter that obscures a casual reader from understanding the
   commonalities between different approaches in mobility management.  A
   first order application of this framework allows us to examine
   previously standardized mobility management protocols, such as MIPv6
   and PMIPv6 (as well as several of their extensions), and describe
   their core functionality in terms of different configurations of the
   logical functions defined by the framework.

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
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 23, 2013.

Copyright Notice

   Copyright (c) 2013 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

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   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.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions and Terminology  . . . . . . . . . . . . . . . . .  4
     2.1.  Conventions used in this document  . . . . . . . . . . . .  4
     2.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Mobility Management Logical Functions  . . . . . . . . . . . .  4
   4.  Functional Representation of Existing Mobility Protocols . . .  5
     4.1.  Mobile IPv6  . . . . . . . . . . . . . . . . . . . . . . .  5
     4.2.  MIPv6 versus PMIPv6  . . . . . . . . . . . . . . . . . . .  6
     4.3.  Hierarchical Mobile IPv6 . . . . . . . . . . . . . . . . .  8
     4.4.  Distributing mobility anchors  . . . . . . . . . . . . . .  9
     4.5.  Migrating Home Agents  . . . . . . . . . . . . . . . . . . 10
   5.  DMM Functional Scenarios . . . . . . . . . . . . . . . . . . . 12
     5.1.  Flat Network Scenario  . . . . . . . . . . . . . . . . . . 12
       5.1.1.  Network-based Mobility Management  . . . . . . . . . . 12
       5.1.2.  Client-based Mobility Management . . . . . . . . . . . 13
     5.2.  Fully distributed scenario with separation of control
           and data planes  . . . . . . . . . . . . . . . . . . . . . 14
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 16
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19

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1.  Introduction

   While there is ongoing research on new protocols for distributed
   mobility management (DMM), it has also been proposed, e.g., in
   [Paper-Distributed.Mobility.PMIP] and in other publications, that a
   distributed mobility management architecture can be designed using
   primarily existing mobility management protocols with some
   extensions.  This is reflected in the requirement presented in [ID-
   dmm-requirements]: distributed mobility management is to first use
   existing protocols and their extensions before considering new
   protocol designs.

   Mobile IPv6 [RFC6275], which is a logically centralized mobility
   management approach addressing primarily hierarchical mobile
   networks, has numerous variants and extensions including, just to
   name a few, PMIPv6 [RFC5213], Hierarchical MIPv6 (HMIPv6) [RFC5380],
   Fast MIPv6 (FMIPv6) [RFC4068] [RFC4988], Proxy-based FMIPv6 (PFMIPv6)
   [RFC5949].  These variants or extensions of MIPv6 have been developed
   over the years owing to the different needs that have been arising
   ever since the first specification of MIP came into life.

   This document argues that we can gain much more insights into this
   design space by abstracting functions of existing mobility management
   protocols in terms of logical functions.  Different variants of
   existing mobility management protocols can then be expressed as
   different design variations of how these logical functions are put
   together.  The result is a rich framework that can express
   sophisticated functionalities in a more straightforward manner and
   can be used to perform gap analysis of existing protocols.  What is
   more, this document shows how to reconfigure these logical functions
   towards various distributed mobility management designs.

   The following subsection presents an overview of this document.

1.1.  Overview

   Section 3 proposes to abstract existing mobility management protocol
   functions into three logical functions, namely, home address
   allocation, mobility routing and location management.  Such
   functional decomposition will enable us to clearly separate data
   plane and the control plane functionality, and gives us the
   flexibility in an implementation to position said logical functions
   at their most appropriate places in the system design.

   Section 4 shows that these logical functions can indeed perform the
   same functions as the major existing mobility protocols.  These
   functions therefore become the foundation for a unified framework
   upon which different designs of distributed mobility management may

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   be built upon.

2.  Conventions and Terminology

2.1.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.2.  Terminology

   All general mobility-related terms and their acronyms used in this
   document are to be interpreted as defined in the Mobile IPv6 base
   specification [RFC6275] and in the Proxy mobile IPv6 specification
   [RFC5213].  These terms include mobile node (MN), correspondent node
   (CN), home agent (HA), local mobility anchor (LMA), and mobile access
   gateway (MAG).

   In addition, this document uses the following terms:

   Mobility routing (MR)  is the logical function that intercepts
      packets to/from the HoA of a mobile node and forwards them, based
      on internetwork location information, either directly towards
      their destination or to some other network element that knows how
      to forward the packets to their ultimate destination.

   Home address allocation  is the logical function that allocates the
      home network prefix or home address to a mobile node.

   Location management (LM)  is the logical function that manages and
      keeps track of the internetwork location information of a mobile
      node, which includes the mapping of the MN HoA to the MN routing
      address or another network element that knows where to forward
      packets destined for the MN.

   Home network of an application session (or an HoA IP address)  is the
      network that has allocated the IP address used as the session
      identifier (HoA) by the application being run in an MN.  The MN
      may be attached to more than one home networks.

3.  Mobility Management Logical Functions

   The existing mobility management functions of MIPv6, PMIPv6, and
   HMIPv6 ca be abstracted into the following logical functions:

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   1.  Anchoring: allocation of home network prefix or HoA to an MN that
       registers with the network;

   2.  Mobility Routing (MR) function: packets interception and
       forwarding to/from the HoA of the MN, based on the internetwork
       location information, either to the destination or to some other
       network element that knows how to forward the packets to their
       destination;

   3.  Internetwork Location Management (LM) function: managing and
       keeping track of the internetwork location of an MN, which
       includes a mapping of the HoA to the mobility anchoring point
       that the MN is anchored to;

   4.  Location Update (LU): provisioning of MN location information to
       the LM function;

   5.  Routing Control (RC): this logical function configures the
       forwarding state of the mobility routing function.

4.  Functional Representation of Existing Mobility Protocols

   This section shows that existing mobility management protocols can be
   expressed as different configurations of the logical functions
   introduced in Section 3 above.

   Using these generic logical functions, we will build up the existing
   mobility protocols one step at a time in the following sequence:
   MIPv6, PMIPv6, HMIPv6, and HAHA.  Functions are added and modified as
   needed in each step.

4.1.  Mobile IPv6

   Figure 1 shows Mobile IPv6 [RFC6275] in a functional representation.
   The combination of the logical functions MR, LM and HoA allocation in
   network1 is the home agent or the mobility anchor.  The mobile node
   MN11 was originally attached to Network1 and was allocated the IP
   prefix for its home address HoA11.  After some time, MN11 moved to
   Network3, from which it is allocated a new prefix to configure the IP
   address IP32.  LM1 maintains the binding HoA11:IP32 so that packets
   from CN21 in Network2 destined to HoA11 will be intercepted by MR1,
   which will then tunnel them to IP32.  MN11 must perform mobility
   signaling using the LU function.

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    Network1     Network3     Network2
    +-----+
    | LM1 |
    +-----+
   location=IP32
   HoA1 alc      IP3 alc      IP2 alc
       |
       |
    +-----+
    | MR1 |
    +-----+
       .
       .      +----+ +----+    +----+
       .      |MN31| |MN11|    |CN21|
       .      |    | |+LU |    |    |
       .      +----+ +----+    +----+
     HoA11     IP31   IP32,
                      HoA11

   Figure 1.  Functional decomposition of Mobile IPv6.

4.2.  MIPv6 versus PMIPv6

   MIPv6 and PMIPv6 both employ the same concept of separating the
   session identifier from the routing address into the HoA and CoA,
   respectively.  Figure 2 contrasts (a) MIPv6 and (b) PMIPv6 by showing
   the destination IP address in the network-layer header as a packet
   traverses from a CN to an MN.

   (a) MIPv6:
   +---+     +---+---+     +---+
   |HoA| --> |HoA|HoA|     |HoA|
   |   |     |   |---|     |---|
   |   |     |   |CoA| ==> |CoA|
   +---+     +---+---+     +---+
    CN          MR         MN+LU

   (b) PMIPv6:
   +---+     +---+---+     +---+---+     +---+
   |HoA| --> |HoA|HoA|     |HoA|HoA| --> |HoA|
   |   |     |   |---|     |---|   |     |   |
   |   |     |   |CoA| ==> |CoA|   |     |   |
   +---+     +---+---+     +---+---+     +---+
    CN          MR           AR+LU         MN

   Figure 2.  Network layer in the protocol stack of packets sent from
   the CN and tunneled (a) to the MN+LU in MIPv6; and (b) to the AR+LU
   in PMIPv6 showing the destination IP address as the packet traverses

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   from the CN to the MN.

   Figure 2 shows that, as far as data-plane traffic is concerned,
   routing from CN to MN+LU in MIPv6 is similar to the route from CN to
   AR+LU in PMIPv6.  The difference is in that the MN with the LU
   function is substituted by the combination of the AR with the LU
   function and the MN.  While additional signaling is needed to enable
   the combination of AR+LU and MN to behave like MN+LU, such signaling
   can be confined between the AR+LU and MN only.  It can therefore be
   seen under this unified formulation, that a host-based mobility
   management protocol can be translated using this substitution into a
   network-based mobility management protocol and vice versa.

   MIPv6 and PMIPv6 bundle all three mobility management logical
   functions: LM1, IP1 prefix allocation, and MR1 into the home agent
   (HA) and Local Mobility Anchor (LMA) respectively.

   The functional representation of Proxy Mobile IPv6 [RFC5213] is shown
   in Figure 3.  In PMIPv6, the combination of LM, MR, and HoA
   allocation is the Local Mobility Anchor (LMA), whereas the AR+LU
   combination together with additional signaling with MN comprises the
   Mobile Access Gateway (MAG).  Here MN11 is attached to the access
   router AR31 which has the IP address IP31 in Network3.  LM1 maintains
   the binding HoA11:IP31.  The access router AR31 also behaves like a
   home link to MN11 so that MN11 can use its original IP address HoA11.

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    Network1     Network3     Network2
    +-----+
    | LM1 |
    +-----+
   HoA1 alc      IP3 alc      IP2 alc
       |
       |
    +-----+
    | MR1 |
    +-----+
       .
       .      +----+           +----+
       .      |AR31|           |CN21|
       .      |+LU |           |    |
       .      +----+           +----+
     HoA11     IP31
                 |
                 |
              +----+
              |MN11|
              +----+
               HoA11

   Figure 3.  Functional representation of PMIPv6.

4.3.  Hierarchical Mobile IPv6

   The functional representation of Hierarchical Mobile IPv6 [RFC5380]
   is shown in Figure 4.

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    Network1     Network3     Network2
    +-----+
    | LM1 |
    +-----+
   HoA1 alc      IP3 alc      IP2 alc
       |
       |
    +-----+      +-----+
    | MR1 |      | MR3 |
    |     |      |+ LM |
    |     |      |proxy|
    +-----+      +-----+
       .           / \
       .          /   \
       .         /     \
       .      +----+ +----+    +----+
       .      |AR31| |MN11|    |CN21|
       .      |+LU | |+LU |    |    |
       .      +----+ +----+    +----+
     HoA11     IP31   IP32,
                 |    HoA11
                 |
              +----+
              |MN31|
              +----+

   Figure 4.  Functional representation of Hierarchical Mobile IPv6.

   Besides the logical functions: LM1, MR1, and HoA1 prefix allocation
   in Network1 as MIPv6 in Figure 2 and PMIPv6 in Figure 3, there is an
   MR function (MR3) in the visited network (Network3).  MR3 is also a
   proxy between LM1 and MN11 in the hierarchical LM function LM1--MR3--
   MN11.  That is, LM1 maintains the LM binding HoA11:MR3 while MR3
   keeps the LM binding HoA11:IP32.  The combined function of MR and the
   LM proxy function is the Mobility Anchor Point (MAP).

   In Figure 4, if MN11 takes the place of MN31 which is attached to
   AR31, the resulting mobility management becomes network-based.

4.4.  Distributing mobility anchors

   It is possible to repeat the mobility anchoring function for any of
   MIPv6, PMIPv6, or HMIPv6, in multiple networks as shown in Figure 5
   which shows such an example with three networks.

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    Network1     Network3     Network2
    +-----+      +-----+      +-----+
    | LM1 |      | LM3 |      | LM2 |
    +-----+      +-----+      +-----+
   HoA1 alc     HoA3 alc     HoA2 alc
       |            |            |
       |            |            |
    +-----+      +-----+      +-----+
    | MR1 |      | MR3 |      | MR2 |
    +-----+      +-----+      +-----+
       .           / \
       .          /   \
       .         /     \
       .      +----+ +----+    +----+
       .      |AR31| |MN11|    |CN21|
       .      |+LU | |+LU |    |    |
       .      +----+ +----+    +----+
     HoA11     IP31   IP32,
                 |    HoA11
                 |
              +----+
              |MN31|
              +----+

   Figure 5.  Functional representation of distributing mobility
   anchors.

4.5.  Migrating Home Agents

   When all these logical functions are bundled into one single entity
   e.g., a home agent in MIPv6 or a local mobility anchor in PMIPv6, in
   a single network, the result is triangular routing when the MN and
   the CN are in networks close to each other but are far from the
   anchor point.

   A method to solve the triangle routing problem is to duplicate the
   anchor points in many networks in different geographic locations as
   in [Paper-Migrating.Home.Agents].  A functional representation of
   Migrating Home Agents is shown in Figure 6.

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    Network1     Network3     Network2
    +-----+      +-----+      +-----+
    | LM0 |------| LM0 |------| LM0 |
    +-----+      +-----+      +-----+
   HoA1 alc     HoA3 alc     HoA2 alc
       |            |            |
       |            |            |
    +-----+      +-----+      +-----+
    | MR1 |      | MR3 |      | MR2 |
    +-----+      +-----+      +-----+
       .           / \
       .          /   \
       .         /     \
       .      +----+ +----+    +----+
       .      |AR31| |MN11|    |CN21|
       .      +----+ +----+    +----+
     HoA11     IP31   IP32,
                 |    HoA11
                 |
              +----+
              |MN31|
              +----+

   Figure 6.  Functional representation of Migrating Home Agents.

   Here, the MR function is available in each of the three networks
   Network1, Network2, and Network3.  The LM function in each network
   (LM0) contains the LM information for all networks.  Each MR in each
   network advertises the HoA IP prefixes of all these networks using
   anycast.  Traffic from CN21 in Network2 destined to HoA11 will
   therefore be intercepted by the MR nearest to CN, which is MR2.
   Using the LM information in LM0, MR2 will use the binding HoA11:IP32
   to tunnel the packets to MN11.

   Similarly, traffic originating from MN11 will be served by its
   nearest MR (MR3).  Triangular routing is therefore avoided.  Yet the
   synchronization of all home agents becomes a challenge as discussed
   in [Paper-SMGI].  In addition, the amount of signaling traffic needed
   in synchronizing the home agents may become excessive when both the
   number of mobile nodes and the number of home agents increase.

   As before, if MN11 in Figure 6 takes the place of MN31 which is
   attached to AR31, the resulting mobility management becomes network-
   based.

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5.  DMM Functional Scenarios

   This section covers the functional description of DMM.  Basically,
   the scenario presents a way to distribute the logical mobility
   functions.  Gap analysis will be made on the functional scenarios.

5.1.  Flat Network Scenario

   In a flat network, the logical functions in the functional
   representation may all be located at the AR as shown in Figures 7 and
   8, respectively.  These two figures depict the network- and client-
   based distributed mobility management scenarios.  The AR is expected
   to support the HoA allocation function.  Then, depending on the
   mobility situation of the MN, the AR can run different functions:

   1.  the AR can act as a legacy IP router;

   2.  the AR can provide the MR function (i.e. act as mobility anchor);

   3.  the AR can provide the LU functions;

   4.  the AR can provide both MR and LU functions.

   For example, [I-D.seite-dmm-dma] and [I-D.bernardos-dmm-distributed-
   anchoring] are PMIPv6 based implementation of this scenario.

5.1.1.  Network-based Mobility Management

   The functional description of network-based mobility management is
   depicted in Figure 7.

   In case (1), MN1 attaches to AR1.  AR advertises prefix HoA1 to MN1
   and then acts as a legacy IP router.  MN1 initiates a communication
   with CN11.

   In case (2), MN1 performs a handover from AR1 to AR3 while
   maintaining ongoing IP communication with CN11.  AR1 becomes the
   mobility anchor for the MN1-CN11 IP communication: AR1 runs MR and LM
   functions for MN1.  AR3 performs LU up to the LM in AR1: AR3
   indicates to AR1 the new location of the MN1.  AR3 allocates a new IP
   prefix (HoA3) for new IP communications.  HoA3 is supposed to be used
   for new IP communication, e.g., if MN1 initiates IP communication
   with CN21.  AR3 shall act as a legacy IP router for MN1-CN21
   communication.

   In case (3), MN1 performs a handover from AR1 to AR2 with ongoing IP
   communication with CN11 and CN21.  AR1 is the mobility anchor for the

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   MN1-CN11 IP communication.  AR3 becomes the mobility anchor for the
   MN1-CN21 IP communication.  Both AR1 and AR3 run MR and LM functions
   for MN1, respectively, anchoring HoA1 and HoA3.  AR2 performs
   location updates up to the LMs in AR1 and AR3 for respectively
   relocate HoA1 and HoA3.

            Network1                Network1     Network3
+----+     HoA1 alc     +----+     HoA1 alc      HoA3 al        +----+
|CN11|      +-----+     |CN11|      +-----+      +-----+        |CN21|
|    |------|     |     |    |------| MR1 |------|     |------- |    |
+----+      |     |     +----+      | LM1 |------|LU31 |        +----+
            | AR1 |                 | AR1 |      |AR3  |
            |     |                 |     |      |     |
            +-----+                 +-----+      +-----+
               |                                    |
               |                                    |
               |                                    |
             +----+                               +----+
             |MN1 |                               |MN1 |
             |    |                               |    |
             +----+                               +----+
             HoA11                                HoA11,
                                                  HoA31
       (1)                              (2)

                                                      Network2
                              Network1                HoA2 al
                  +----+     HoA1 alc                 +-----+
                  |CN11|      +-----+                 |     |
                  |    |------| MR1 |-----------------|LU21 |-------+
                  +----+      | LM1 |-----------------|AR2  |       |
                              | AR1 |                 |     |       |
                              |     |      Network3   +-----+       |
                              +-----+      HoA3 al     | |        +----+
                                           +-----+     | |        |MN1 |
                               +----+      |MR3  |------ |        |    |
                               |CN21|      |LM3  |--------        +----+
                               |    |------|     |                HoA11,
                               +----+      |AR3  |                HoA31
                                           +-----+       (3)

   Figure 7.  Network-based DMM architecture for a flat network.

5.1.2.  Client-based Mobility Management

   The functional description of client-based mobility management is
   depicted in Figure 8.

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   In case (1), MN1 attaches to AR1.  AR advertises the prefix HoA1 to
   MN1 then acts as a legacy IP router.  MN1 initiates a communication
   with CN11.

   In case (2), MN1 performs a handover from AR1 to AR3 with ongoing IP
   communication with CN11.  AR1 becomes the mobility anchor for the
   MN1-CN11 IP communication: AR1 runs MR and LM functions for MN1.  The
   MN performs LU directly up to the LM in AR1 or via AR3; in this case
   AR3 acts as a proxy locator (pLU) (e.g. as a FA in MIPv4).  AR3
   allocates a new IP prefix (HoA3) for new IP communications.  HoA3 is
   supposed to be used for new IP communications, e.g., if MN1 initiates
   IP communication with CN21.  AR3 shall act as a legacy IP router for
   MN1-CN21 communication.

              Network1                Network1     Network3
  +----+     HoA1 alc     +----+     HoA1 alc                     +----+
  |CN11|      +-----+     |CN  |      +-----+      +-----+        |CN21|
  |    |------|     |     |    |------| MR1 |------|     |------- |    |
  +----+      |     |     +----+      | LM1 |------|pLU31|        +----+
              | AR1 |                 | AR1 |      |AR31 |
              |     |                 |     |      |     |
              +-----+                 +-----+      +-----+
                 |                                    |
                 |                                    |
                 |                                    |
               +----+                               +----+
               |MN1 |                               |MN1 |
               |    |                               |LU31|
               +----+                               +----+
               HoA11                                HoA11,
                                                    IP31

        (1)                              (2)

   Figure 8.  Client-based DMM architecture for a flat network.

5.2.  Fully distributed scenario with separation of control and data
      planes

   This scenario considers multiple MRs and a distributed LM database.

   The different use case scenarios of distributed mobility management
   are described in [I-D.yokota-dmm-scenario] as well as in [Paper-
   Distributed.Mobility.Review].  The architecture described in this
   document is mainly on separating the data plane from the control
   plane.

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   Figure 9 shows an example DMM architecture with the same three
   networks as in Figure 5.  As is in Figure 5, each network in Figure 9
   has its own IP prefix allocation function.  In the data plane, the
   mobility routing function is distributed to multiple locations at the
   MRs so that routing can be optimized.  In the control plane, the MRs
   may exchange signaling with each other.  In addition to these
   features in Figure 5, the LM function in Figure 9 is a distributed
   database, with multiple servers, of the mapping of HoA to CoA.

    Network1     Network3     Network2
    +-----+      +-----+      +-----+
    | LM1 |      | LM3 |      | LM2 |
    +-----+      +-----+      +-----+
   HoA1 alc     HoA3 alc     HoA2 alc
       | \ \      / | \      / / |
       |  \  \   /  |  \   /  /  |
       |   \   \/   |   \/   /   |
       |    \  / \  |  / \  /    |
       |     \/    \|/    \/     |
       |     /\    /|\    /\     |
       |    /  \ /  |  \ /  \    |
       |   /   /\   |   /\   \   |
       |  /  /   \  |  /   \  \  |
       | / /      \ | /      \ \ |
    +-----+      +-----+      +-----+
    | MR1 |------| MR3 |------| MR2 |
    +-----+      +-----+      +-----+
       .           / \
       .          /   \
       .         /     \
       .      +----+ +----+    +----+
       .      |AR31| |MN11|    |CN21|
       .      |+LU | |+LU |    |    |
       .      +----+ +----+    +----+
     HoA11     IP31   IP32,
                 |    HoA11
                 |
              +----+
              |MN31|
              +----+

   Figure 9.  A distributed architecture for mobility management.

   To perform mobility routing, the MRs need the location information
   which is maintained at the LMs.  The MRs are therefore the clients of
   the LM servers and may also send location updates to the LM as the
   MNs perform the handover.  The location information may either be

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   pulled from the LM servers by the MR, or pushed to the MR by the LM
   servers.  In addition, the MR may also cache a limited amount of
   location information.

   This figure shows three MRs (MR1, MR2, and MR3) in three networks.
   MN11 has moved from the first network supported by MR1 and LM1 to the
   third network supported by MR3 and LM3.  It may use an HoA (HoA11)
   allocated to it when it was in the first network for those
   application sessions that had already started when MN11 was attached
   there and that require session continuity after the handover to the
   third network.  When MN11 was in the first network, no location
   management is needed so that LM1 will not keep an entry of HoA11.
   After MN11 has performed its handover to the third network, the
   database server LM1 maintains a mapping of HoA11 to MR3.  That is,
   LM1 points to the third network and it is the third network that will
   keep track of how to reach MN11.  Such a hierarchical mapping can
   prevent frequent update signaling to LM1 as MN11 performs intra-
   network handover within the third network.  In other words, the
   concept of hierarchical mobile IP [RFC5380] is applied here but only
   in location management and not in routing in the data plane.

6.  Security Considerations

   TBD

7.  IANA Considerations

   None

8.  References

8.1.  Normative References

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

8.2.  Informative References

   [I-D.bernardos-dmm-distributed-anchoring]
              Bernardos, CJ. and JC. Zuniga, "PMIPv6-based distributed
              anchoring", draft-bernardos-dmm-distributed-anchoring-01
              (work in progress), September 2012.

   [I-D.bernardos-dmm-pmip]
              Bernardos, C., Oliva, A., Giust, F., Melia, T., and R.

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              Costa, "A PMIPv6-based solution for Distributed Mobility
              Management", draft-bernardos-dmm-pmip-01 (work in
              progress), March 2012.

   [I-D.jikim-dmm-pmip]
              Kim, J., Koh, S., Jung, H., and Y. Han, "Use of Proxy
              Mobile IPv6 for Distributed Mobility Management",
              draft-jikim-dmm-pmip-00 (work in progress), March 2012.

   [I-D.liebsch-mext-dmm-nat-phl]
              Liebsch, M., "Per-Host Locators for Distributed Mobility
              Management", draft-liebsch-mext-dmm-nat-phl-02 (work in
              progress), October 2012.

   [I-D.liu-dmm-dynamic-anchor-discussion]
              Liu, D., Deng, H., and W. Luo, "DMM Dynamic Anchor
              Discussion", draft-liu-dmm-dynamic-anchor-discussion-00
              (work in progress), March 2012.

   [I-D.liu-dmm-pmip-based-approach]
              Liu, D., Song, J., and W. Luo, "PMIP Based DMM
              Approaches", draft-liu-dmm-pmip-based-approach-02 (work in
              progress), March 2012.

   [I-D.luo-dmm-pmip-based-dmm-approach]
              Luo, W. and J. Liu, "PMIP Based DMM Approaches",
              draft-luo-dmm-pmip-based-dmm-approach-01 (work in
              progress), March 2012.

   [I-D.ma-dmm-armip]
              Ma, Z. and X. Zhang, "An AR-level solution support for
              Distributed Mobility Management", draft-ma-dmm-armip-00
              (work in progress), February 2012.

   [I-D.patil-dmm-issues-and-approaches2dmm]
              Patil, B., Williams, C., and J. Korhonen, "Approaches to
              Distributed mobility management using Mobile IPv6 and its
              extensions", draft-patil-dmm-issues-and-approaches2dmm-00
              (work in progress), March 2012.

   [I-D.sarikaya-dmm-dmipv6]
              Sarikaya, B., "Distributed Mobile IPv6",
              draft-sarikaya-dmm-dmipv6-00 (work in progress),
              February 2012.

   [I-D.seite-dmm-dma]
              Seite, P. and P. Bertin, "Distributed Mobility Anchoring",
              draft-seite-dmm-dma-05 (work in progress), July 2012.

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   [I-D.xue-dmm-routing-optimization]
              Xue, K., Li, L., Hong, P., and P. McCann, "Routing
              optimization in DMM",
              draft-xue-dmm-routing-optimization-00 (work in progress),
              June 2012.

   [I-D.yokota-dmm-scenario]
              Yokota, H., Seite, P., Demaria, E., and Z. Cao, "Use case
              scenarios for Distributed Mobility Management",
              draft-yokota-dmm-scenario-00 (work in progress),
              October 2010.

   [MHA]      Wakikawa, R., Valadon, G., and J. Murai, "Migrating Home
              Agents Towards Internet-scale Mobility Deployments",
               Proceedings of the ACM 2nd CoNEXT Conference on Future
              Networking Technologies,  Lisboa, Portugal, December 2006.

   [Paper-Distributed.Centralized.Mobility]
              Bertin, P., Bonjour, S., and J-M. Bonnin, "Distributed or
              Centralized Mobility?",  Proceedings of Global
              Communications Conference (GlobeCom), December 2009.

   [Paper-Distributed.Dynamic.Mobility]
              Bertin, P., Bonjour, S., and J-M. Bonnin, "A Distributed
              Dynamic Mobility Management Scheme Designed for Flat IP
              Architectures",  Proceedings of 3rd International
              Conference on New Technologies, Mobility and Security
              (NTMS), 2008.

   [Paper-Distributed.Mobility.Management]
              Chan, H., "Distributed Mobility Management with Mobile
              IP",  Proceedings of IEEE ICC 2012 Workshop on
              Telecommunications: from Research to Standards, June 2012.

   [Paper-Distributed.Mobility.PMIP]
              Chan, H., "Proxy Mobile IP with Distributed Mobility
              Anchors",  Proceedings of GlobeCom Workshop on Seamless
              Wireless Mobility, December 2010.

   [Paper-Distributed.Mobility.Review]
              Chan, H., Yokota, H., Xie, J., Seite, P., and D. Liu,
              "Distributed and Dynamic Mobility Management in Mobile
              Internet: Current Approaches and Issues", February 2011.

   [Paper-Host.based.DMM]
              Lee, JH., Bonnin, JM., and X. Lagrange, "Host-based
              Distributed Mobility Management Support Protocol for IPv6
              Mobile Networks",  Proceedings of IEEE WiMob, Barcelona,

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              Spain, October 2012.

   [Paper-Migrating.Home.Agents]
              Wakikawa, R., Valadon, G., and J. Murai, "Migrating Home
              Agents Towards Internet-scale Mobility Deployments",
               Proceedings of the ACM 2nd CoNEXT Conference on Future
              Networking Technologies, December 2006.

   [Paper-Net.based.DMM]
              Giust, F., de la Oliva, A., Bernardos, CJ., and RPF. Da
              Costa, "A network-based localized mobility solution for
              Distributed Mobility Management",  Proceedings of 14th
              International Symposium on Wireless Personal Multimedia
              Communications (WPMC), October 2011.

   [Paper-SMGI]
              Zhang, L., Wakikawa, R., and Z. Zhu, "Support Mobility in
              the Global Internet",  Proceedings of ACM Workshop on
              MICNET, MobiCom 2009, Beijing, China, September 2009.

   [RFC4068]  Koodli, R., "Fast Handovers for Mobile IPv6", RFC 4068,
              July 2005.

   [RFC4988]  Koodli, R. and C. Perkins, "Mobile IPv4 Fast Handovers",
              RFC 4988, 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.

   [RFC5949]  Yokota, H., Chowdhury, K., Koodli, R., Patil, B., and F.
              Xia, "Fast Handovers for Proxy Mobile IPv6", RFC 5949,
              September 2010.

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

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Authors' Addresses

   H Anthony Chan
   Huawei Technologies
   5340 Legacy Dr. Building 3, Plano, TX 75024, USA
   Email: h.a.chan@ieee.org

   Pierrick Seite
   France Telecom - Orange
   4, rue du Clos Courtel, BP 91226, Cesson-Sevigne 35512, France
   Email: pierrick.seite@orange-ftgroup.com

   Kostas Pentikousis
   Huawei Technologies
   Carnotstr. 4 10587 Berlin, Germany
   Email: k.pentikousis@huawei.com

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