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DMM                                                              H. Chan
Internet-Draft                                       Huawei Technologies
Intended status: Informational                             March 9, 2015
Expires: September 10, 2015


                      Enhanced Mobility Anchoring
            draft-chan-dmm-distributed-mobility-anchoring-00

Abstract

   This document defines the mobility management protocol solutions in
   the context of a distributed mobility management deployment.  Such
   solutions consider the problem of assigning a mobility anchor and a
   gateway at the initiation of a session.  In addition, the mid-session
   switching of the mobility anchor in a distributed mobility management
   environment is considered.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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 September 10, 2015.

Copyright Notice

   Copyright (c) 2015 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
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   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as



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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions and Terminology  . . . . . . . . . . . . . . . . .  3
   3.  Anchor Selection and Switching . . . . . . . . . . . . . . . .  5
     3.1.  IP anchoring in network of attachment  . . . . . . . . . .  5
     3.2.  IP anchoring not in network of attachment  . . . . . . . .  6
     3.3.  Changing IP anchoring in mid-session . . . . . . . . . . .  7
     3.4.  Moving IP anchoring in mid-session . . . . . . . . . . . .  7
     3.5.  Anchoring a session  . . . . . . . . . . . . . . . . . . .  8
     3.6.  Changing session anchoring in mid-session  . . . . . . . .  9
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 11
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 11
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12































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1.  Introduction

   A key requirement in distributed mobility management
   [I-D.ietf-dmm-requirements] is to enable traffic to avoid traversing
   single mobility anchor far from the optimal route.  Recent
   developments in research and standardization with respect to future
   deployment models call for far more flexibility in network function
   operation and management.  For example, the work on service function
   chaining at the IETF (SFC WG) has already identified a number of use
   cases for data centers.  Although the work in SFC is not primarily
   concerned with mobile networks, the impact on IP-based mobile
   networks is not hard to see as by now most hosts connected to the
   Internet do so over a wireless medium.  For instance, as a result of
   a dynamic re-organization of service chain a non-optimal route
   between mobile nodes may arise if pme relies solely on centralized
   mobility management.  As discussed earlier in the distributed
   mobility management working group (DMM WG) this may also occur when
   the mobile node has moved such that both the mobile node and the
   correspondent node are far from the mobility anchor via which the
   traffic is routed.

   Recall that distributed mobility management solutions do not make use
   of centrally deployed mobility anchor.  As such, an application
   session SHOULD be able to have its traffic passing from one mobility
   anchor to another as the mobile node moves, or when changing
   operation and management (OAM) requirements call for mobility anchor
   switching, thus avoiding non-optimal routes.  This draft proposes
   enhanced mobility anchoring.


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].

   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], the Proxy Mobile IPv6 specification
   [RFC5213], and the DMM current practices and gap analysis [RFC7429].
   This includes terms such as mobile node (MN), correspondent node
   (CN), home agent (HA), home address (HoA), care-of-address (CoA),
   local mobility anchor (LMA), and mobile access gateway (MAG).

   In addition, this document uses the following term:






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   Home network of an application session (or of an HoA):  the network
      that has allocated the IP address (HoA) used for the session
      identifier by the application running in an MN.  An MN may be
      running multiple application sessions, and each of these sessions
      can have a different home network.

   Anchoring Function (AF):  allocation to a mobile node of an IP
      address, i.e., Home Address (HoA), or prefix, i.e., Home Network
      Prefix (HNP) topologically anchored by the advertising node.  That
      is, the anchor node is able to advertise a connected route into
      the routing infrastructure for the allocated IP prefixes.  This is
      a basic function of a mobility anchor.  With separation of control
      plane and data plane, this function may reside in a control plane
      anchor.  Then the anchor function performs the IP prefix or
      address allocation and the route advertisement for an IP anchor in
      the data plane.

   Session anchoring:  A session or a flow is anchored to a node or
      nodes when the packets of the flow traverse at least one such
      nodes.

   IP anchoring:  An IP address or prefix is typologically anchored to a
      node by an anchor function.  The IP packet will travel along a
      route which traverses that node.  The packet will also traverse
      that node if the IP address does not change.  Yet the IP address
      is changed at another node before it reaches that node, it will be
      redirected with the new IP address along a new route which may not
      traverse the original node.

   Internetwork Location Management (LM) function:  managing and keeping
      track of the internetwork location of an MN.  The location
      information may be a binding of the IP advertised address/prefix,
      e.g., HoA or HNP, to the IP routing address of the MN or of a node
      that can forward packets destined to the MN.  It is a control
      plane function.

      In a client-server protocol model, location query and update
      messages may be exchanged between a Location Management client
      (LMc) and a Location Management server (LMs).  With separation of
      control plane and data plane, this function may reside in a
      control plane anchor.

   Forwarding Management (FM) function:  Forwarding Management (FM)
      function: packet interception and forwarding to/from the IP
      address/prefix assigned to 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.



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      With separation of control plane and data plane, FM may split into
      a FM part in the control plane (FM-CP) which may be a function in
      a control plane anchor or mobility controller and a FM part in the
      data plane (FM-DP) which may be the function of a data plane
      anchor.


3.  Anchor Selection and Switching

   When an IP prefix or address is topologically anchored to a node
   (data plane node), the anchor function will advertise connected route
   for it.  Then an IP packet with this IP address as its destination
   address will be forwarded along a path that traverses through this IP
   anchoring node.

   When a session or flow is anchored to a node (data plane node), the
   packets of the flow will traverse at least one such session anchoring
   node.

   A session anchoring node may differ from an IP anchoring node for an
   IP address of the session.

3.1.  IP anchoring in network of attachment

   An IP prefix or address may be anchored to the access router to which
   the MN is attached.

   For example, when an MN attaches to a network or moves to a new
   network, it is allocated an IP prefix from that network.  It
   configures from this prefix an IP address which is typically a
   dynamic IP address.  It then uses this IP address when it starts a
   new application session (an IP flow).  Packets to the MN in this flow
   simply follows the forwarding table for as long as the MN stays in
   that network.

   In this example, the flow may have terminated before the MN moves to
   a new network.  Otherwise, the flow may close and then restart using
   a new IP address configured in the new network.













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  Net1                                                  Net2
  +--------------+                                      +--------------+
  |node anchoring|                                      |node anchoring|
  | address IP1  |                                      | address IP2  |
  +--------------+                                      +--------------+
                                                        +--------------+
                                                        |MN(IP2)       |
                                                        |running       |
                                                        |session IP2   |
                                                        +--------------+

   Figure 1.  IP anchoring in network of attachment.

3.2.  IP anchoring not in network of attachment

   An IP prefix or address may be anchored to an access router in a
   different network to which the MN is attached.  The anchor function
   is then in a network different from the network of attachment.

   An example is in using a static IP address which does not belong to
   the network of attachment.

   Another example when an MN moves to a new network is as follows.  The
   MN has an ongoing session which was initialized in a prior network of
   attachment using an IP address belonging to the network where it was
   initialized as was described in Section 3.1.  When the session is
   unable to change its IP address it may continue to use its original
   IP address which is anchored not in the current network of attachment
   but in the network where the original IP address belongs.  Mobility
   support is needed to enable the ongoing session to use this original
   IP address.



  Net1                                                  Net2
  +--------------+                                      +--------------+
  |node anchoring|                                      |node anchoring|
  | address IP1  |                                      | address IP2  |
  +--------------+                                      +--------------+

                                                        +--------------+
                                                        |MN(IP2)       |
                                                        |running       |
                                                        |session IP1   |
                                                        +--------------+

   Figure 2.  IP anchoring not in network of attachment.




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3.3.  Changing IP anchoring in mid-session

   With the MN in the example in Section 3.1 it may be desirable that
   the flow can change to the new IP address configured in the new
   network.  The packets of this flow may then follow the forwarding
   table without requiring IP layer mobility support.  Yet the flow may
   be using a higher layer mobility support which is not in the scope of
   this document to change the IP address of the flow.



  Net1                                                  Net2
  +--------------+                                      +--------------+
  |node anchoring|                                      |node anchoring|
  | address IP1  |                                      | address IP2  |
  +--------------+                                      +--------------+

  +--------------+                                      +--------------+
  |MN(IP1) with  |                 move                 |MN(IP2) with  |
  |session over  |               =======>               |session IP1   |
  |IP1           |                                      |changed to IP2|
  +--------------+                                      +--------------+

   Figure 3.  Changing IP anchoring.

3.4.  Moving IP anchoring in mid-session

   The IP anchoring may move without changing the IP address of the
   flow.


  Net1                                                  Net2
  +--------------+                                      +--------------+
  |node anchoring|                 move                 |node anchoring|
  | address IP1  |               =======>               | address IP1  |
  +--------------+                                      +--------------+

  +--------------+                                      +--------------+
  |MN(IP1)       |                 move                 |MN(IP2)       |
  |running       |               =======>               |running       |
  |session IP1   |                                      |session IP1   |
  +--------------+                                      +--------------+

   Figure 4.  Moving IP anchoring.

   As an MN with an ongoing session move to a new network, the session
   may preserve session continuity by moving the IP anchoring of its
   original IP address to the new network.  Then the IP anchoring which



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   was advertising the prefix in the original network will need to move
   to the new network.  As the IP anchoring in the new network
   advertises the prefix of the session in the new network, the
   forwarding tables will be updated so that packets of the ongoing
   session will follow the updated forwarding tables.

3.5.  Anchoring a session

   As an MN with an ongoing session move to a new network, the session
   may use the original IP address for session continuity by anchoring
   the session to some nodes (data plane nodes) and redirecting the
   packets of this session to traverse through these session anchoring
   nodes.


                             Net3
                             +--------------+
  Net1                       |node anchoring|           Net2
  +--------------+          /|address of CN |           +--------------+
  |     anchoring|         / +--------------+           |     anchoring|
  |   session    |        /                             |   session    |
  |  identified  |       /   +--------------+           |  identified  |
  |   with IP1   |      /    |      CN      |           |   with IP1   |
  |              |     /     +--------------+           |              |
  |session IP1   |    /                                 |session IP1   |
  |--> addr AR2  |   /                                  |--> MN        |
  |--------------|  /                                   |--------------|
  |node anchoring|<-                                    |AR2  anchoring|
  | address IP1  | ------------------------------------>| address IP2  |
  +--------------+                                      +--------------+

  +--------------+                                      +--------------+
  |MN(IP1)       |                 move                 |MN(IP2)       |
  |running       |               =======>               |running       |
  |session IP1   |                                      |session IP1   |
  +--------------+                                      +--------------+

   Figure 5.  Session anchoring.

   For example, a first node to anchor the session may be at the IP
   anchoring of the original IP address in the original network.  A
   second node to anchor the session may be in the new network.  Then
   packets of this session traverse the session anchoring in both the
   original network and the new network.  Forwarding management function
   at these nodes may be used to direct the flow to traverse them.

   The session's packets from the CN to the MN will then first be
   forwarded to the IP anchoring node in the original network where it



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   is intercepted by the first session anchoring node.  The session
   anchoring node may possess fowarding management function to forward
   the packets to the second session anchoring node in the new network.

   In host-based mobility management, the session may be anchored in the
   new network to the MN itself.

   In network-based mobility management, the session may be anchored to
   an access router to which the MN is attached in the new network The
   access router may then forward the packet to the MN at L2.

3.6.  Changing session anchoring in mid-session

   The route of the packets of an ongoing session traversing the
   original network and the MN's new network of attachment is not
   necessarily optimal.  It can be unneccessarily long especially when
   the session anchoring nodes are far from each other even when the MN
   and CN are close to each other.  A shorter route results when the
   session is anchored in both the CN's network and the MN's network.
   An example to achieve this is to move the session anchoring from the
   original network to the CN's network.






























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  0123456789012345678901234567890123456789012345678901234567890123456789

                             Net3
                             +--------------+
                             |     anchoring|
                             |   session    |
                             |  identified  |
                             |   with IP1   |
                             |              |
                          ..>|session IP1   |
                         .   |--> addr AR2  |
                        .    |--------------|
  Net1                 .     |node anchoring|           Net2
  +--------------+    .      |address of CN |\          +--------------+
  |     anchoring|   .       +--------------+ \         |     anchoring|
  |   session    |  .                          \        |   session    |
  |  identified  | .         +--------------+   \       |  identified  |
  |   with IP1   |.          |      CN      |    \      |   with IP1   |
  |              |           +--------------+     \     |              |
  |session IP1   |                                 \    |session IP1   |
  |--> addr AR2  |                                  \   |--> MN L2 addr|
  |--------------|                                   \  |--------------|
  |node anchoring|                                    ->|AR2  anchoring|
  | address IP1  |                                      | address IP2  |
  +--------------+                                      +--------------+

  +--------------+                                      +--------------+
  |MN(IP1)       |                 move                 |MN(IP2)       |
  |running       |               =======>               |running       |
  |session IP1   |                                      |session IP1   |
  +--------------+                                      +--------------+

   Figure 6.  Changing session anchoring.


4.  Security Considerations

   TBD


5.  IANA Considerations

   This document presents no IANA considerations.


6.  References





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6.1.  Normative References

   [I-D.ietf-dmm-requirements]
              Chan, A., Liu, D., Seite, P., Yokota, H., and J. Korhonen,
              "Requirements for Distributed Mobility Management",
              draft-ietf-dmm-requirements-17 (work in progress),
              June 2014.

   [I-D.seite-dmm-dma]
              Seite, P., Bertin, P., and J. Lee, "Distributed Mobility
              Anchoring", draft-seite-dmm-dma-07 (work in progress),
              February 2014.

   [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.

   [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.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)",
              RFC 6241, June 2011.

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

   [RFC7429]  Liu, D., Zuniga, JC., Seite, P., Chan, H., and CJ.
              Bernardos, "Distributed Mobility Management: Current
              Practices and Gap Analysis", RFC 7429, January 2015.

6.2.  Informative References

   [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.




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Author's Address

   H Anthony Chan
   Huawei Technologies
   5340 Legacy Dr. Building 3
   Plano, TX 75024
   USA

   Email: h.a.chan@ieee.org










































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