Distributed Mobility Management: Current practices and gap analysis
draft-ietf-dmm-best-practices-gap-analysis-01

+---------------+-------+  +----------+  +-------------+    =====
   |Residential |  |H(e)NB |  | Backhaul |  |Mobile       |   ( IP  )
   |Enterprise  |..|-------|..|          |..|Operator     |..(Network)
   |Network     |  |L-GW   |  |          |  |Core network |   =======
   +---------------+-------+  +----------+  +-------------+
                       /
                       |
                       /
                    +-----+
                    | UE  |
                    +-----+

                        Figure 8: LIPA architecture

   Both SIPTO and LIPA have a very limited mobility support, specially
   in 3GPP specifications up to Rel-10.  In Rel-11, there is currently a
   work item on LIPA Mobility and SIPTO at the Local Network (LIMONET)
   [3GPP.23.859] that is studying how to provide SIPTO and LIPA
   mechanisms with some additional, but still limited, mobility support.
   In a glimpse, LIPA mobility support is limited to handovers between
   HeNBs that are managed by the same L-GW (i.e., mobility within the
   local domain), while seamless SIPTO mobility is still limited to the
   case where the SGW/PGW is at or above Radio Access Network (RAN)
   level.

5.  Gap analysis

   The goal of this section is to identify the limitations in the
   current practices with respect to providing the expected DMM
   functionality.

   From the analysis performed in Section 4, we can first identify a
   basic set of functions that a DMM solution needs to provide:

   o  Multiple (distributed) anchoring: ability to anchor different
      sessions of a single mobile node at different anchors.  In order
      to make this feature "DMM-friendly", some anchors might need to be
      placed closer to the mobile node.

   o  Dynamic anchor assignment/re-location: ability to i) optimally
      assign initial anchor, and ii) dynamically change the initially
      assigned anchor and/or assign a new one (this may also require to
      transfer mobility context between anchors).  This can be achieved
      either by changing anchor for all ongoing sessions, or by
      assigning new anchors just for new sessions.

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   o  Multiple IP address management: ability of the mobile node to
      simultaneously use multiple IP addresses and select the best one
      (from an anchoring point of view) to use on a per-session/
      application/service basis.  Depending on the mobile node support,
      this functionality might require more or less support from the
      network side.  This is typically the role of a connection manager.

   In order to summarize the previously listed functions, Figure 9 shows
   an example of a conceptual DMM solution deployment.

        (                                                  )
         +------------------------------------------------+
              /                  |                  \
             /    * Internet     |      x Internet   \         Internet
            /    * / access      |     x / access     \       / access
           /    * / (IP a)       |    x / (IP b)       \     /
        --+------+-----      ----+-----+----      ------+---+----
        | distributed | * * *| distributed |      | distributed |
        |   anchor 1  |      |   anchor i  |      |   anchor n  |
        ---+-----------      ---+-----------      ---+-----------
           |                    |                    |
          (o)                  (o)                  (o)
                  session X   * x  session Y
                   anchored  * x   anchored
                     at 1   * x      at i
                    (IP a) (o)      (IP b)
                            |
                         +--+--+
                         | MN1 |
                         +-----+

                          Figure 9: DMM functions

   Based on the analysis performed in Section 4, the following list of
   gaps can be identified:

   o  Both the main client- and network-based IP mobility protocols,
      namely (DS)MIPv6 and PMIPv6 allows to deploy multiple anchors
      (i.e., home agents and localized mobility anchors), therefore
      providing the multiple anchoring function.  However, existing
      solutions do only provide an optimal initial anchor assignment, a
      gap being the lack of dynamic anchor change/new anchor assignment.
      Neither the HA switch nor the LMA runtime assignment allow
      changing the anchor during an ongoing session.  This actually
      comprises several gaps: ability to perform anchor assignment at
      any time (not only at the initial MN's attachment), ability of the
      current anchor to initiate/trigger the relocation, and ability of
      transferring registration context between anchors.

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   o  The dynamic anchor relocation needs to ensure that IP address
      continuity is guaranteed for sessions that need it at the
      relocated anchor.  This for example implies having the knowledge
      of which sessions are active at the mobile node, which is
      something typically known only by the MN (namely, by its
      connection manager).  Therefore, (part of) this knowledge might
      need to be transferred to/shared with the network.

   o  Dynamic discovery and selection of anchors.  There might be more
      than one available anchor for a mobile node to use.  Currently,
      there is no efficient mechanism that allows to dynamically
      discover the presence of nodes that can play the role of anchor,
      discover their capabilities and allow the selection of the most
      suitable one.

   o  NOTE: This section is in progress.  More gaps are still to be
      identified and more text added to these bullets (perhaps even
      assigning one subsection to each one).  More discussion/feedback
      from the group is still needed.

6.  Security Considerations

   TBD.

7.  IANA Considerations

   None.

8.  Informative References

   [3GPP.23.829]
              3GPP, "Local IP Access and Selected IP Traffic Offload
              (LIPA-SIPTO)", 3GPP TR 23.829 10.0.1, October 2011.

   [3GPP.23.859]
              3GPP, "Local IP access (LIPA) mobility and Selected IP
              Traffic Offload (SIPTO) at the local network", 3GPP
              TR 23.859 12.0.1, April 2013.

   [3GPP.29.060]
              3GPP, "General Packet Radio Service (GPRS); GPRS
              Tunnelling Protocol (GTP) across the Gn and Gp interface",
              3GPP TS 29.060 3.19.0, March 2004.

   [I-D.gundavelli-v6ops-community-wifi-svcs]

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              Gundavelli, S., Grayson, M., Seite, P., and Y. Lee,
              "Service Provider Wi-Fi Services Over Residential
              Architectures",
              draft-gundavelli-v6ops-community-wifi-svcs-06 (work in
              progress), April 2013.

   [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-05 (work in progress),
              June 2013.

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

   [RFC4225]  Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E.
              Nordmark, "Mobile IP Version 6 Route Optimization Security
              Design Background", RFC 4225, December 2005.

   [RFC4640]  Patel, A. and G. Giaretta, "Problem Statement for
              bootstrapping Mobile IPv6 (MIPv6)", RFC 4640,
              September 2006.

   [RFC5026]  Giaretta, G., Kempf, J., and V. Devarapalli, "Mobile IPv6
              Bootstrapping in Split Scenario", RFC 5026, October 2007.

   [RFC5142]  Haley, B., Devarapalli, V., Deng, H., and J. Kempf,
              "Mobility Header Home Agent Switch Message", RFC 5142,
              January 2008.

   [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.

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

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

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

   [RFC6463]  Korhonen, J., Gundavelli, S., Yokota, H., and X. Cui,

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              "Runtime Local Mobility Anchor (LMA) Assignment Support
              for Proxy Mobile IPv6", RFC 6463, February 2012.

   [RFC6611]  Chowdhury, K. and A. Yegin, "Mobile IPv6 (MIPv6)
              Bootstrapping for the Integrated Scenario", RFC 6611,
              May 2012.

   [RFC6705]  Krishnan, S., Koodli, R., Loureiro, P., Wu, Q., and A.
              Dutta, "Localized Routing for Proxy Mobile IPv6",
              RFC 6705, September 2012.

Authors' Addresses

   Dapeng Liu (editor)
   China Mobile
   Unit2, 28 Xuanwumenxi Ave, Xuanwu District
   Beijing  100053
   China

   Email: liudapeng@chinamobile.com

   Juan Carlos Zuniga (editor)
   InterDigital Communications, LLC
   1000 Sherbrooke Street West, 10th floor
   Montreal, Quebec  H3A 3G4
   Canada

   Email: JuanCarlos.Zuniga@InterDigital.com
   URI:   http://www.InterDigital.com/

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

   Email: pierrick.seite@orange.com

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

   Email: h.a.chan@ieee.org

   Carlos J. Bernardos
   Universidad Carlos III de Madrid
   Av. Universidad, 30
   Leganes, Madrid  28911
   Spain

   Phone: +34 91624 6236
   Email: cjbc@it.uc3m.es
   URI:   http://www.it.uc3m.es/cjbc/

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