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MULTIMOB Working Group                                       D. von Hugo
Internet-Draft                             Deutsche Telekom Laboratories
Intended status: Informational                                 H. Asaeda
Expires: August 26, 2010                                 Keio University
                                                             B. Sarikaya
                                                              Huawei USA
                                                                P. Seite
                                                 France Telecom - Orange
                                                       February 22, 2010


 Evaluation of further issues on Multicast Mobility:  Potential future
                          work for WG MultiMob
              <draft-von-hugo-multimob-future-work-01.txt>

Abstract

   The WG MultiMob aims at defining a basic mobile multicast solution
   leveraging on network localized mobility management, i.e.  Proxy
   Mobile IPv6 protocol.  The solution would be basically based on
   multicast group management, i.e.  IGMP/MLD, proxying at the access
   gateway.  If such a basic solution is essential from an operational
   point of view, challenges with efficient resource utilization and
   user perceived service quality still persist.  These issues may
   prevent large scale deployments of mobile multicast applications.

   This document attempts to identify topics for future extension of
   work such as modifying base PMIPv6 and MLD/IGMP for optimal multicast
   support, extending to and modifying of MIPv4/v6 and DSMIP, sender
   (source) mobility, consideration of Handover optimization, multiple
   flows with multihoming and any other different issues.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   The list of current Internet-Drafts can be accessed at



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   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on August 26, 2010.

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   described in the BSD License.






























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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  7
   3.  IGMP/MLD Proxy Architecture  . . . . . . . . . . . . . . . . .  7
   4.  Problem Description  . . . . . . . . . . . . . . . . . . . . .  8
     4.1.  Modification of base PMIPv6 for optimal multicast
           support  . . . . . . . . . . . . . . . . . . . . . . . . .  8
     4.2.  Modification of MLD/IGMP for optimal multicast support . .  8
     4.3.  Extensions to and modifying of MIPv4/v6 and DSMIPv6  . . .  9
     4.4.  Consideration of sender (source) mobility  . . . . . . . .  9
     4.5.  Consideration of Handover Optimization . . . . . . . . . .  9
     4.6.  Support of multiple flows  . . . . . . . . . . . . . . . . 10
     4.7.  Support of multi-hop transmission  . . . . . . . . . . . . 10
     4.8.  Mobility agnosticity . . . . . . . . . . . . . . . . . . . 10
     4.9.  Local routing  . . . . . . . . . . . . . . . . . . . . . . 10
   5.  Requirements on Solutions  . . . . . . . . . . . . . . . . . . 11
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14



























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1.  Introduction

   Recently chartered WG MultiMob focuses on documentation of proper
   configuration and usage of existing (specified standard) protocols
   within both mobility and multicast related areas to enable and
   support mobility for multicast services and vice versa.  Although the
   final recommendation is not yet available it is expected that such a
   solution following the remote subscription aproach will not be
   resource efficient nor grant the service quality expected by the end
   user.

   Such a solution would resolve the problem to ensure multicast
   reception in PMIPv6-enabled [RFC5213] networks without appropriate
   multicast support.  However it would neither automatically minimize
   multicast forwarding delay to provide seamless and fast handovers for
   real-time services nor minimize packet loss and reordering that
   result from multicast handover management as stated in
   [I-D.irtf-mobopts-mmcastv6-ps].  Also Route Optimization is out of
   scope of the basic solution - an issue for reducing amount of
   transport resource usage and transmission delay.  Thus possible
   enhancements and issues for solutions beyond a basic solution need to
   be described to enable current PMIPv6 protocols to fully support
   efficient mobile multicast services.  Such extensions may include
   protocol modifications for both mobility and multicast related
   protocols to achieve optimizations for resource efficient and
   performance increasing multimob approaches.  The document includes
   the case of mobile multicast senders using Any Source Multicast (ASM)
   and Source Specific Multicast (SSM) [RFC4607].

   Figure 1 illustrates the key components of the foreseen basic
   Multimob solution.  The extended multicast mobility scenario, leading
   to above issues, is sketched in Figure 2.



















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           +------+          +------+
          |  MN  |  =====>   |  MN  |
          +------+           +------+
             |                  .
             |                  .
          +--------+          +--------+
          | MAG 1  |          | MAG 2  |
          |IGMP/MLD|          |IGMP/MLD|
          |Proxy   |          |Proxy   |
          +--------+          +--------+
              |                |
              ***  ***  ***  ***
             *   **   **   **   *
            *                    *
             *  Internet Subnet *
            *                    *
             *   **   **   **   *
              ***  ***  ***  ***
               |               |
          +-------+          +-------+
          | LMA 1 |          | LMA 2 |
          +-------+          +-------+
              |                |
              ***  ***  ***  ***
             *   **   **   **   *
            *                    *
             *  Fixed Internet  *
            *                    *
             *   **   **   **   *
              ***  ***  ***  ***
                     |
                    +------+
                    |  CN  |
                    +------+

           Figure 1: MultiMob Scenario for chartered PMIP6 issue















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    +------+           +------+        +------+
    |  MN  |  =====>   |  MN  | ====>  |  MN  |
    +------+           +------+        +------+
       |                  .             .
       |                  .            .
       |                  .           .
    +-------+          +-------+   +-------+   +-------+
    | MAG 1 |          | MAG 2 |   |  AR 1 |   | AR 2  |
    |IGMP/MLD|         |IGMP/MLD|  |IGMP/MLD|  |IGMP/MLD|
    |Proxy  |          |Proxy  |   |Proxy  |   |Proxy  |
    +-------+          +-------+   +-------+   +-------+
             \          /           |             |
       ***  ***   ***  ***        ***  ***   ***  ***
      *   **   ***   **   *      *   **   ***   **   *
     *                     *    *                     *
      * Internet Subnet 1 *      * Internet Subnet 2 *
     *                     *    *                     *
      *   **   ***   **   *      *   **   ***   **   *
       ***  ***   ***  ***        ***  ***   ***  ***
       |                 |         |
    +-------+          +-------+   |
    | LMA 1 |          | LMA 2 |  /
    +-------+          +-------+ /
         \                |     /
          ***  ***  ***  ***   /     ***  ***   ***   ***
         *   **   **   **   * /     *   **   ***   **    *
        *                    *     *                     *
         *  Fixed Internet  *       * Internet Subnet 3 *
        *                    *_____*                     *
         *   **   **   **   *       *   **   ***   **   *
          ***  ***  ***  ***         *** .***   ***  ***
               |                       .
           +-------+          +-------+
           |  CN   |  ====>   |  CN   |
           +-------+          +-------+

         Figure 2: MultiMob scenario for extended MultiMob issues

   In summary additional to a 'Single hop, link, flow' Proxy MIP
   mobility for listening MNs (scenario shown in Figure 1), the future
   work will focus on optimization of performances and extend the
   scenario to 'Multi-hop, -homed, -flow' client mobility, thus also
   including optimizations for MIPv6 [RFC3775].  The following is the
   proposed work items to be covered in the MultiMob continuation: (see
   Figure 2).

   o  Modification of base PMIPv6 and MLD/IGMP for optimal multicast
      support.



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   o  Extension to and modifying of MIPv4/v6 and DSMIP using IGMP/MLD
      Proxy and the Foreign Agent/ Access Router.

   o  Consideration of sender (source) mobility.

   o  Consideration of Handover optimization.

   o  Support of multiple flows on multihomed mobile nodes.

   o  Multi-hop transmission.

   o  Fixed mobile convergence support.

   o  Consideration of earlier versions of IGMP and MLD in the
      solutions.

   o  Consideration of locally available multicast without remote
      subscription.

   o  Improve host mobility agnoticity

   o  Routing optimization


2.  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 BCP 14 [RFC2119].

   This document uses the terminology defined in [RFC3775], [RFC3376],
   [RFC3810], [RFC5213], [I-D.irtf-mobopts-mmcastv6-ps].


3.  IGMP/MLD Proxy Architecture

   Multimob basic solution is based on IGMPv3/MLDv2 Proxy support at the
   mobile access gateway (MAG) of Proxy Mobile IPv6 as shown in
   Figure 1.  IGMPv3/MLDv2 proxy keeps multicast state on the
   subscriptions of the mobile nodes and only an aggregate state is kept
   at the local mobility anchor (LMA).  When LMA receives multicast data
   it can forward it to the MAG without duplication because MAG takes of
   the packet duplication.  This leads to solving the avalanche problem.

   By keeping multicast state locally, IGMPv3/MLDv2 Proxy introduces
   mobility related problems such as possible packet loss when a mobile
   node does a handover to another MAG and its multicast state is not
   modified fast enough at the LMA.



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   IGMPv3/MLDv2 introduces tunnel convergence problem which occurs when
   a given MAG serves MNs that belong to different LMAs and MNs
   subscribe to the same multicast group.  In that case MNs receive
   duplicate multicast data forwarded from more than one LMA.

   It can be foreseen that mobile access gateways will serve both mobile
   and fixed terminals concurrently.  The tuning of multicast-related
   protocol parameters based on the terminal characteristics is needed.
   Parameters only applicable to mobile users need to be distinguished
   from the parameters applicable to fixed users.  It should be also
   possible to distinguish between slow and fast movement and handover
   frequency to form corresponding tunnels for mobile users.

   Based on the above observations we will state the problems next and
   then list the requirements on possible solutions.


4.  Problem Description

   The general issues of multicast mobility are extensively discussed
   and described in [I-D.irtf-mobopts-mmcastv6-ps].  To reduce the
   complexity of the pleothera of requirements listed in
   [I-D.irtf-mobopts-mmcastv6-ps] and in
   [I-D.deng-multimob-pmip6-requirement] this document tries to propose
   lightweight solutions for multicast mobility which allow for easy
   deployment within realistic scenarios and architectures, and which
   build directly on basic MultiMob solution which is based on IGMP/MLD
   Proxy at the mobile access gateway.

4.1.  Modification of base PMIPv6 for optimal multicast support

   There would be potential solutions proposed for multicast
   optimization for PMIPv6 such as
   [I-D.asaeda-multimob-pmip6-extension], agent-based reling on
   additional encapsulation, and a hybrid approach.  Since other
   functional enhancements of PMIPv6 are currently under way in NETEXT
   WG, both the impact of new features on Mobile Multicast as well as a
   potential Multicast-initiated proposal for PMIPv6 modification have
   to be considered in a continuous exchange process between both WGs.

4.2.  Modification of MLD/IGMP for optimal multicast support

   Potential approaches for enhancement of group management as specified
   e.g. by MLDv2 [RFC3810] include default timer value modification,
   specific query message introduction, and standard (query) reaction
   suppression, beside introducing multicast router attendance control
   in terms of e.g. specification of a Listener Hold message as proposed
   in [I-D.asaeda-multimob-igmp-mld-mobility-extensions].



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4.3.  Extensions to and modifying of MIPv4/v6 and DSMIPv6

   Operational interest clearly focusses on network-based mobility
   approaches, but in the framework of multiple technologies serving a
   mobile user there will be demand to include also other non-PMIPv6
   based specifications.

   This section addresses the compatibility of PMIPv6-based multicast
   solutions with MIPv6 [RFC3775], i.e. handover between network-based
   and client mobility support as well as interoperabiliy between IPv4
   and IPv6 mechanisms (e.g.  FA handling, IPv4/v4-tunneling) with
   mobile multicast.  DSMIPv6 [RFC5555] has a basic support for
   multicast which is based on remote subscription and bi-directional
   tunneling, but does not specify how to achieve group management and
   data forwarding unless the mobility anchor (i.e.  Home Agent) is a
   fully functional IPv6 multicast router.

4.4.  Consideration of sender (source) mobility

   We see future demand for such a feature in terms of applications such
   as 'Push to talk over wireless technologies' (packet based point-to-
   multipoint (P2MP) group voice) like 3GPP or WiMAX, 'Multi-party
   mobile audio/video conferencing', 'mobile multi-player gaming' etc,
   where due to real-time constraints a solution based on a central
   server might add too much delay.

   According to [I-D.irtf-mobopts-mmcastv6-ps] generally (i.e. for ASM)
   a mobile multicast source must provide address transparency at
   Routing - for Reverse Path Forwarding (RPF) checks - as well as on
   Transport layer - to coincide with packet source address at receiver
   side.  Further issues are temporal handover constraints, possible
   packet loss and multicast scoping, and enhanced complexity of inter-
   domain multicasting.  Additional challenges arise for SSM (Source
   Specific Multicast) due to the principle of multicast decoupling
   between sender and receivers.

4.5.  Consideration of Handover Optimization

   This work item would deal with reduction of delay, packet loss, and
   packet reordering effort.  In case these degradations are induced due
   to terminal movement it will be discussed how to make use of MIPSHOP
   approaches such as HMIP, FMIP etc. (predominantly focusing on intra-
   technology handover).  Reusing multicast specific protocol extensions
   exceeding IGMP/MLD modifications shall further decrease the impact of
   group management induced delay.






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4.6.  Support of multiple flows

   Considering a per-flow handover for parallel multicast sessions
   allows to treat different services requirements and labels of flows
   independently.  This would improve user perceived service performance
   as well as allow for more efficient usage of network resources
   because of the enabled flexibility.

4.7.  Support of multi-hop transmission

   This scenario adds another level of complexity to Multicast Mobility
   and is of interest e.g. in nested NEMO (Network Mobility, [RFC3963])
   scenarios, for MANETs (Mobile Adhoc NETworks) where also mechanisms
   for multicast forwarding are dicussed, e.g. in terms of Simplified
   Multicast Forwarding (SMF, [I-D.ietf-manet-smf]) or for
   infrastructure mesh networks.  Here, more than the mobile and
   temporary character of connections, it is the existence of (more or
   less stable) multiple hops and multiple paths which is stressed.

4.8.  Mobility agnosticity

   In the idea of network based mobility management, the mobile node
   should remain agnostic of the multicast mobility management when
   roaming.  In particular, the node MUST not be required to re-
   subscribe to multicast group(s) after handoff.  If the mobile node
   does no re-resubscribes, the new MAG must be able to retrieve the
   multicast states corresponding to the moving node.

4.9.  Local routing

   Short term deployment focuses on architecture where multicast traffic
   is provided via the home network.  However, depending on the network
   topology, namely the location of the content delivery network, the
   LMA may not be on the optimal multicast service delivery path.  This
   enables mobile nodes to access locally available multicast services
   such as local channels.

   Figure 3 illustrates the use-case for local routing.













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                                 +----+
                                 |LMA |
                                 +----+
                                   |
                                   |
                           ***  ***  ***  ***
                          *   **   **   **   *
                         *                    *        +-------------+
                          *  Local Routing   *   _____ | Content     |
                         *                    *        | Delivery    |
                                                       | Network     |
                          *   **   **   **   *         +-------------+
                           ***  ***  ***  ***
                            ||            ||
                          +----+        +----+
                          |MAG1|        |MAG2|
                          +----+        +----+
                           |  |            |
                           |  |            |
                          MN1 MN2          MN3



                     Figure 3: local Multicast routing

   In such a case, the MAG should act as a multicast router to construct
   the optimal multicast delivery path.  If the MAG also supports MLD
   proxy function issue raises up on the dual mode behaviour.  In such a
   case, a pragmatic approach could be to leverage only on multicast
   routing at the MAG in the PMIP domain.

   Whatever is the MAG operation mode, the multicast state is locally
   kept at the access gateway, so unknown from the mobility anchor.  In
   other words, the multicast service is independent from the mobility
   service that the mobile node is receiving from the network in the
   form of PMIPv6 or DSMIPv6.  However, handover support is still
   desirable but cannot be provided by the mobility anchor (i.e.  HA or
   LMA).  In such a case mobility support for locally available
   multicast should be provided by extending multicast protocols of IGMP
   or MLD.


5.  Requirements on Solutions

   This section tries to identify requirements from the issues discussed
   in previous section.





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   o  Seamless handover (low latency and during the handover).
   o  Similar packet loss to unicast service.
   o  Multiple LMAs architecture.
   o  Agnostic mobile host re-subscription.  So, MAGs must be able to
      retrieve multicast contexts of the mobile nodes.
   o  Solution address IPv6, IPv4 only and dual stack nodes.
   o  Supports sender (source) mobility.
   o  Optimal local routing.
   o  To be completed...


6.  Security Considerations

   This draft introduces no additional messages.  Compared to [RFC3376],
   [RFC3810], and [RFC3775][RFC5213] there is no additional threats to
   be introduced.


7.  IANA Considerations

   None.


8.  Acknowledgements

   The authors would thank all active mebers of MultiMob WG, especially
   (in no specific order) Gorry Fairhurst, Jouni Korhonen, Thomas
   Schmidt, Suresh Krishnan and Matthias Waehlisch for providing
   continuous support and helpful comments.


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.

   [RFC3314]  Wasserman, M., "Recommendations for IPv6 in Third
              Generation Partnership Project (3GPP) Standards",
              RFC 3314, September 2002.

   [RFC3376]  Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
              Thyagarajan, "Internet Group Management Protocol, Version
              3", RFC 3376, October 2002.

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



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   [RFC3810]  Vida, R. and L. Costa, "Multicast Listener Discovery
              Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.

   [RFC4607]  Holbrook, H. and B. Cain, "Source-Specific Multicast for
              IP", RFC 4607, August 2006.

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

   [RFC5555]  Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and
              Routers", RFC 5555, June 2009.

9.2.  Informative References

   [23246]    "3GPP TS 23.246 V8.2.0, Multimedia Broadcast/Multicast
              Service (MBMS); Architecture and functional description
              (Release 8).", 2008.

   [23401]    "3GPP TS 23.401 V8.2.0, General Packet Radio Service
              (GPRS) enhancements for Evolved Universal Terrestrial
              Radio Access Network (E-UTRAN) access (Release 8).", 2008.

   [23402]    "3GPP TS 23.402 V8.4.1, Architecture enhancements for non-
              3GPP accesses (Release 8).", 2009.

   [I-D.asaeda-multimob-igmp-mld-mobility-extensions]
              Asaeda, H. and T. Schmidt, "IGMP and MLD Hold and Release
              Extensions for Mobility",
              draft-asaeda-multimob-igmp-mld-mobility-extensions-03
              (work in progress), July 2009.

   [I-D.asaeda-multimob-igmp-mld-optimization]
              Asaeda, H., "IGMP and MLD Optimization for Mobile Hosts
              and Routers",
              draft-asaeda-multimob-igmp-mld-optimization-01 (work in
              progress), October 2009.

   [I-D.asaeda-multimob-pmip6-extension]
              Asaeda, H., Seite, P., and J. Xia, "PMIPv6 Extensions for
              Multicast", draft-asaeda-multimob-pmip6-extension-02 (work
              in progress), July 2009.

   [I-D.deng-multimob-pmip6-requirement]
              Deng, H., Chen, G., Schmidt, T., Seite, P., and P. Yang,
              "Multicast Support Requirements for Proxy Mobile IPv6",
              draft-deng-multimob-pmip6-requirement-02 (work in
              progress), July 2009.




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   [I-D.ietf-16ng-ipv4-over-802-dot-16-ipcs]
              Madanapalli, S., Park, S., Chakrabarti, S., and G.
              Montenegro, "Transmission of IPv4 packets over IEEE
              802.16's IP Convergence Sublayer",
              draft-ietf-16ng-ipv4-over-802-dot-16-ipcs-06 (work in
              progress), June 2009.

   [I-D.ietf-manet-smf]
              Macker, J. and S. Team, "Simplified Multicast Forwarding",
              draft-ietf-manet-smf-09 (work in progress), July 2009.

   [I-D.irtf-mobopts-mmcastv6-ps]
              Fairhurst, G., Schmidt, T., and M. Waehlisch, "Multicast
              Mobility in MIPv6: Problem Statement and Brief Survey",
              draft-irtf-mobopts-mmcastv6-ps-09 (work in progress),
              October 2009.

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

   [RFC5121]  Patil, B., Xia, F., Sarikaya, B., Choi, JH., and S.
              Madanapalli, "Transmission of IPv6 via the IPv6
              Convergence Sublayer over IEEE 802.16 Networks", RFC 5121,
              February 2008.


Authors' Addresses

   Dirk von Hugo
   Deutsche Telekom Laboratories
   Deutsche-Telekom-Allee 7
   64295 Darmstadt, Germany

   Email: dirk.von-hugo@telekom.de


   Hitoshi Asaeda
   Keio University
   Graduate School of Media and Governance
   5322 Endo
   Fujisawa, Kanagawa  252-8520
   Japan

   Email: asaeda@wide.ad.jp
   URI:   http://www.sfc.wide.ad.jp/~asaeda/





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   Behcet Sarikaya
   Huawei USA
   1700 Alma Dr. Suite 500
   Plano, TX  75075

   Email: sarikaya@ieee.org


   Pierrick Seite
   France Telecom - Orange
   4, rue du Clos Courtel
   BP 91226
   Cesson-Sevigne, BZH  35512
   France

   Email: pierrick.seite@orange-ftgroup.com



































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