DMM Working Group                                             M. Liebsch
Internet-Draft                                                       NEC
Intended status: Standards Track                        October 15, 2012
Expires: April 18, 2013


         Distributed Mobility Management - Framework & Analysis
              draft-liebsch-dmm-framework-analysis-00.txt

Abstract

   Mobile operators consider the distribution of mobility anchors to
   enable offloading some traffic from their core network.  The
   Distributed Mobility Management (DMM) Working Group is investigating
   the impact of decentralized mobility management to existing protocol
   solutions, while taking into account well defined requirements, which
   are to be met by a future solution.  This document discusses DMM
   using a functional framework.  Functional Entities to support DMM as
   well as reference points between these Functional Entities are
   introduced and described.  The described functional framework allows
   distribution and co-location of Functional Entities and build a DMM
   architecture that matches the architecture of available protocols.
   Such methodology eases the analysis of best current practices with
   regard to functional and protocol gaps.

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 April 18, 2013.

Copyright Notice

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

   This document is subject to BCP 78 and the IETF Trust's Legal



Liebsch                  Expires April 18, 2013                 [Page 1]


Internet-Draft          DMM Framework & Analysis            October 2012


   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
   2.  Conventions and Terminology  . . . . . . . . . . . . . . . . .  4
   3.  Functional Architecture for DMM Support  . . . . . . . . . . .  5
   4.  Different Constellations of Functional Entities  . . . . . . .  9
     4.1.  Condensed Deployment: Mobility Anchor Centric Solutions  .  9
     4.2.  Cooperative Deployment: Distributed Architecture . . . . . 10
   5.  Analysis of enabling technology according to different
       deployment models  . . . . . . . . . . . . . . . . . . . . . . 12
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   8.  Normative References . . . . . . . . . . . . . . . . . . . . . 15
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16



























Liebsch                  Expires April 18, 2013                 [Page 2]


Internet-Draft          DMM Framework & Analysis            October 2012


1.  Introduction

   The concept of Distributed Mobility Management (DMM) in based on the
   distribution of mobility anchors towards the access networks to
   provide mobile nodes with local anchors and enable optimal routing of
   traffic above anchor level to any kind of serving point, e.g.
   distributed content caches.  The closer mobility anchors are located
   to mobile nodes, the more a mobile node's handover may necessitate
   the assignment of a new mobility anchor.  Continuity of a mobile
   node's IP address or IP address prefix enables IP session continuity,
   but creates the problem of routing downlink packets to the mobile
   node's current mobility anchor.  Different solutions and associated
   extensions to IP mobility management protocols are being discussed to
   maintain a mobile node's IP session after mobility anchor relocation,
   including solutions that are based on existing protocols.

   This document defines a framework for DMM and describes an initial
   set of well defined functional entities (FE), which are required to
   support IP address continuity in a network with distributed mobility
   anchors.  Having identified the function of each FE as well as
   required interfaces between FEs allows different constellations of
   FEs, either by co-locating or distributing them.  We consider such
   framework of particular importance for the discussion of Best Current
   Practices (BCP) to enable DMM, and for performing a Gap Analysis
   while assigning the defined FEs to architecture components of
   existing protocols.

   The initial version of this draft introduces a basic set of FEs and
   interfaces between these FEs to support IP address continuity in DMM,
   without being specific to the used mobility management protocol,
   which operates below the mobility anchor.




















Liebsch                  Expires April 18, 2013                 [Page 3]


Internet-Draft          DMM Framework & Analysis            October 2012


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].














































Liebsch                  Expires April 18, 2013                 [Page 4]


Internet-Draft          DMM Framework & Analysis            October 2012


3.  Functional Architecture for DMM Support

   The framework introduces five functional entities (FE) which are
   relevant to DMM to meet essential DMM requirements as per
   [I-D.ietf-dmm-requirements], such as enabling temporary IP address
   continuity after a mobile node got assigned a new mobility anchor.
   Further FEs may be needed to enable advanced features, such as
   simultaneous use of an imported mobile node HoA or HNP to maintain
   ongoing data sessions and a new HoA or HNP, which is allocated by the
   mobile node's new mobility anchor after handover.  Additional FEs are
   not considered in this first version of the draft, but can be
   introduced easily in future versions of the draft and considered for
   the BCP discussion and gap analysis.

   The following FEs are considered so far to suit basic DMM
   requirements:

   o  FE_R: Functional Entity of a standard IP Router / Switch

   o  FE_MA: Functional Entity Mobility Anchor

   o  FE_MCTX: Functional Entity Mobility Context Transfer

   o  FE_I: Functional Entity Ingress to DMM plane

   o  FE_E: Functional Entity Egress of DMM plane

   o  FE_IEC: Functional Entity for Ingress/Egress Control

   The list comprises a generic router/switch function FE_R that's
   supposed to build the transport network.  It has no particular
   function that's specific to DMM, but performs routing according to a
   longest prefix match.  Deployment specific aspects, such as the use
   of IP/MPLS, are not (yet) considered in this draft.

   The entity FE_MA represents an unmodified function of the mobility
   architecture's mobility anchor.  In Mobile IPv6, this function would
   be co-located with the Home Agent, in Proxy Mobile IPv6, this
   function would be co-located with the Local Mobility Anchor (LMA).
   In a cellular IP (CIP) enabled domain, this function would be co-
   located with the domain's CIP Gateway.

   The task of the FE_MCTX is to export relevant binding cache
   information, such as the mobile node's HoA or HNP, from the mobile
   node's previous mobility anchor (pMA) during mobility anchor
   relocation to enable IP address continuity after mobility anchor
   relocation.  Furthermore, the function allows importing mobility
   context on the mobile node's new mobility anchor.  Imported HoA/HNP



Liebsch                  Expires April 18, 2013                 [Page 5]


Internet-Draft          DMM Framework & Analysis            October 2012


   of a mobile node will be treated as identifier and non-routable IP
   address (prefix), as it probably does not match the new mobility
   anchor's location in the topology.  Furthermore, the FE_MCTX can
   provide mobility context to the FE_IEC to allow keeping these
   policies updated, which allow forwarding of packets to the MN's
   currently used mobility anchor.

   The function FE_I enables deviations from the standard routing path
   of the mobile node's downlink packets, which carry the mobile node's
   HoA/HNP in the destination IP address field of their IP header.
   Uplink packets are currently assumed to be routable, as the mobile
   node's topologically incorrect IP address (prefix) is carried in the
   source address field.  No filtering according to source addresses is
   currently considered.  The FE_I can retrieve information from a
   control function (FE_IEC) to establish forwarding of the mobile
   node's packets to the appropriate DMM egress function (FE_E).
   Forwarding can be for example accomplished by an IP tunnel to the
   egress function, address translation to a routable IP address or
   other means.

   The function FE_E receives downlink packets being forwarded by the
   DMM ingress function FE_I, e.g. by terminating a forwarding tunnel.
   The state on the FE_I can be established through the DMM ingress/
   egress control function (FE_IEC) and is used to identify an MN's
   received packets and deliver them to the MN's current mobility anchor
   (FE_MA).  If the FE_E is co-located with the FE_MA, the delivery is a
   local operation.  If the FE_E is not co-located with the FE_MA, other
   techniques, such as host-routes or technology such as OpenFlow may be
   used to deliver the packets to the mobile node's current mobility
   anchor.  If not co-located with the FE_MA, the FE_E is supposed to be
   located close to the mobile node's current FE_MA.

   The function FE_IEC represents a control function, that establishes,
   updates and removes policies (per-host or grouped) in the FE_I and
   the FE_E to allow forwarding of a mobile node's downlink packets
   towards the mobile node's current mobility anchor.















Liebsch                  Expires April 18, 2013                 [Page 6]


Internet-Draft          DMM Framework & Analysis            October 2012


                Control Plane:        :        Data Plane:
                                      :
                                      :         |data packet
                                      :         v for mobile node
              +----+      R_IC        :      +----+
              |FE_I|<----------+      :      |FE_I|
              +----+           |      :      +----+
                          +--+ |      :         |
                      R_II|  | |      :         |
                          v  v v      :         |
                         +------+     :         |
                         |FE_IEC|     :         |
                         +------+     :         |
                           ^  ^       :         v
              +----+       |  |       :      +----+
              |FE_E|<------+  |R_XC   :      |FE_E|
              +----+  R_EC    |       :      +----+
                              v       :         |
                           +-------+  :         |
                           |FE_MCTX|  :         |
                           +-------+  :         |
                            ^  ^  ^   :         v
              +-----+       |  |  |   :      +-----+
              |FE_MA|<------+  +--+   :      |FE_MA|
              +-----+  R_XA    R_XX   :      +-----+


     Figure 1: Basic set of functional entities (FE) and interfaces to
                    enable IP-address continuity in DMM

   The reference points between FEs comprise the following features:

   o  R_XA: Enables the FE_MCTX to retrieve mobility context information
      from the FE_MA of the MN's mobility anchor.  Such information
      includes for example the MN's Home Address (HoA) or Home Network
      Prefix (HNP).  In the network of the MN's new mobility anchor, the
      reference point enables the FE_MCTX to provide the MN's mobility
      context to the associated FE_MA, that imports the MN's mobility
      context to enable IP address continuity.

   o  R_XX: Enables the direct transfer of an MN's mobility context
      between two functions FE_MCTX, which are typically located in the
      network of the MN's previous and new mobility anchor respectively.

   o  R_IC: Enables the FE_IEC to provide policies to the FE_I, which
      are used to forward the MN's downlink packets towards the MN's new
      mobility anchor and the associated FE_E. These policies can be
      provided to the FE_I in an unsolicited manner or on request by the



Liebsch                  Expires April 18, 2013                 [Page 7]


Internet-Draft          DMM Framework & Analysis            October 2012


      FE_I.

   o  R_EC: Enables the FE_IEC to provide policies to the FE_E, which
      are used at the FE_E to identify received packets that belong to a
      particular MN and deliver these packets to the MN's new mobility
      anchor.  Such policies could include, for example, tunnel endpoint
      information, flow identification rules or other identification and
      addressing rules.

   o  R_XC: Enables initialization and update of the FE_IEC about the
      MN's mobility context as well as about its current location as
      represented by the FE_E in the network of the MN's current
      mobility anchor.

   o  R_II: Multiple instances of an FE_IEC can be deployed to build a
      DMM architecture, e.g. to distribute load and scale better, or
      distribute tasks associated with the FE_IEC to enable cooperative
      solutions.

































Liebsch                  Expires April 18, 2013                 [Page 8]


Internet-Draft          DMM Framework & Analysis            October 2012


4.  Different Constellations of Functional Entities

   The defined FEs can be grouped or distributed to build a DMM
   architecture that considers new architecture components or that is
   based on components of existing protocols.  As a starting point, this
   section depicts and describes two deployment variants, which reflect
   the current understanding of the WG how DMM could be accomplished
   using existing protocol specifications as base.  Variants of these
   two deployment models or entirely new models are possible and can be
   added to future versions of this document.

   Note: This section is incomplete and needs further input on different
   deployment models and variants.

4.1.  Condensed Deployment: Mobility Anchor Centric Solutions

   Mobility Anchor centric solutions aim at extensions to available
   mobility protocols to enable DMM, without being dependent on any
   external, non-mobility component and protocol.  IP address continuity
   is typically established on the control plane by extensions to the
   mobility protocol to convey an MN's mobility context to a new
   mobility anchor, and on the data plane by the establishment of a
   forwarding tunnel between mobility anchors to deliver downlink
   packets from the originally assigned mobility anchor to the MN's
   currently used mobility anchor after anchor relocation.


























Liebsch                  Expires April 18, 2013                 [Page 9]


Internet-Draft          DMM Framework & Analysis            October 2012


               |data destined
               v to mobile node (MN)
             +----+
             |FE_R|
             +----+
               |
               |
               |
               |
               |
               |
           +---v--------------+                 +------------------+
           | +----+           |                 | +----+           |
           | |FE_I|--==========================-->|FE_E|           |
           | +----+           |                 | +----+           |
           |        +------+  |                 |   |    +------+  |
           |        |FE_IEC|  |                 |   |    |FE_IEC|  |
           |        +------+  |                 |   |    +------+  |
           |                  |                 |   |              |
           |        +-------+ |                 |   |    +-------+ |
           |        |FE_MCTX| |                 |   |    |FE_MCTX| |
           |        +-------+ |                 |   v    +-------+ |
           | +-----+          |                 | +-----+          |
           | |FE_MA|          |                 | |FE_MA|          |
           | +-----+          |                 | +-----+          |
           +------------------+                 +---|--------------+
             MN's previous MA                       |  MN's current MA
                                                    v
                                                   +--+
                                                   |MN|
                                                   +--+

     Figure 2: Condensed Deployment: Mobility Anchor Centric Solutions

4.2.  Cooperative Deployment: Distributed Architecture

   A distributed architecture considers protocol operation between
   distributed FEs, aiming at a DMM solution that's to a large extent
   independent of the mobility architecture and protocol.  A further
   goal is to establish optimal routing paths for the MN's traffic after
   the MN's mobility anchor has been relocated and IP address continuity
   must be provided.









Liebsch                  Expires April 18, 2013                [Page 10]


Internet-Draft          DMM Framework & Analysis            October 2012


                  |data destined
                  v to mobile node (MN)
                +----+
                |FE_R|
                +----+
                  |
                  v
                +----+
                |FE_I|----------------------------------------+
                +----+                                        |
                                    +------+                  |
                                    |FE_IEC|                  |
                                    +------+                  |
                                                              |
              +------------------+             +--------------v----+
              |        +-------+ |             | +-------+  +----+ |
              |        |FE_MCTX| |             | |FE_MCTX|  |FE_E| |
              |        +-------+ |             | +-------+  +----+ |
              | +-----+          |             |              |    |
              | |FE_MA|          |             |           +-----+ |
              | +-----+          |             |           |FE_MA| |
              +------------------+             |           +-----+ |
                  MN's previous                +--------------|----+
                  mobility                      MN's current  v
                  anchor                        mobility    +--+
                                                anchor      |MN|
                                                            +--+

        Figure 3: Cooperative Deployment: Distributed Architecture






















Liebsch                  Expires April 18, 2013                [Page 11]


Internet-Draft          DMM Framework & Analysis            October 2012


5.  Analysis of enabling technology according to different deployment
    models

   Note: This section is incomplete.  A Gap analysis can be performed
   based on input from Section 4 about different deployment models and
   variants.  A reasonable set of models can be mapped to the
   architecture of existing protocols from within or beyond the IP
   mobility protocol solution space.











































Liebsch                  Expires April 18, 2013                [Page 12]


Internet-Draft          DMM Framework & Analysis            October 2012


6.  Security Considerations

   Different constellations of Functional Entities may allow re-use of
   existing protocols' security mechanisms to protect DMM protocol
   operation.  In particular in a distributed model, new interfaces must
   be protected, e.g. to counteract unauthorized packet redirection to a
   different, possibly malicious mobility anchor.  Details about
   security threats will be studied when the placement of Functional
   Entities for a selected set of preferred deployment models becomes
   mature.









































Liebsch                  Expires April 18, 2013                [Page 13]


Internet-Draft          DMM Framework & Analysis            October 2012


7.  IANA Considerations

   As this document represents a framework and no protocol
   specification, there is no need for IANA actions.















































Liebsch                  Expires April 18, 2013                [Page 14]


Internet-Draft          DMM Framework & Analysis            October 2012


8.  Normative References

   [I-D.ietf-dmm-requirements]
              Chan, A., "Requirements for Distributed Mobility
              Management", draft-ietf-dmm-requirements-02 (work in
              progress), September 2012.

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










































Liebsch                  Expires April 18, 2013                [Page 15]


Internet-Draft          DMM Framework & Analysis            October 2012


Author's Address

   Marco Liebsch
   NEC Laboratories Europe
   NEC Europe Ltd.
   Kurfuersten-Anlage 36
   D-69115 Heidelberg,
   Germany

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








































Liebsch                  Expires April 18, 2013                [Page 16]