Network Working Group                                      H. Chan (Ed.)
Internet-Draft                                       Huawei Technologies
Intended status: Informational                         September 7, 2012
Expires: March 11, 2013

            Requirements for Distributed Mobility Management


   This document defines the requirements for Distributed Mobility
   Management (DMM) in IPv6 deployments.  The traditionally hierarchical
   structure of cellular networks has led to deployment models which are
   in practice centralized.  Mobility management with logically
   centralized mobility anchoring in current mobile networks is prone to
   suboptimal routing and raises scalability issues.  Such centralized
   functions can lead to single points of failure and inevitably
   introduce longer delays and higher signaling loads for network
   operations related to mobility management.  The objective is to
   enhance mobility management in order to meet the primary goals in
   network evolution, i.e., improve scalability, avoid single points of
   failure, enable transparent mobility support to upper layers only
   when needed, and so on.  Distributed mobility management must be
   secure and compatible with existing network deployments and end

Status of this Memo

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   This Internet-Draft will expire on March 11, 2013.

Copyright Notice

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

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions used in this document  . . . . . . . . . . . . . .  5
     2.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Centralized versus distributed mobility management . . . . . .  5
     3.1.  Centralized mobility management  . . . . . . . . . . . . .  6
     3.2.  Distributed mobility management  . . . . . . . . . . . . .  7
   4.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Distributed deployment . . . . . . . . . . . . . . . . . .  8
     4.2.  Transparency to Upper Layers when needed . . . . . . . . .  9
     4.3.  IPv6 deployment  . . . . . . . . . . . . . . . . . . . . . 10
     4.4.  Existing mobility protocols  . . . . . . . . . . . . . . . 10
     4.5.  Compatibility  . . . . . . . . . . . . . . . . . . . . . . 10
     4.6.  Security considerations  . . . . . . . . . . . . . . . . . 11
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   7.  Co-authors and Contributors  . . . . . . . . . . . . . . . . . 12
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 13
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 13
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15

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1.  Introduction

   In the past decade a fair number of mobility protocols have been
   standardized [RFC6275] [RFC5944] [RFC5380] [RFC6301] [RFC5213].
   Although the protocols differ in terms of functions and associated
   message formats, we can identify a few key common features:

      a centralized mobility anchor providing global reachability and an
      always-on experience to the user;

      extensions to the base protocols to optimize handover performance
      while users roam across wireless cells; and

      extensions to enable the use of heterogeneous wireless interfaces
      for multi-mode terminals (e.g. smartphones).

   The presence of the centralized mobility anchor allows a mobile node
   to remain reachable when it is not connected to its home domain.  The
   anchor point, among other tasks, ensures connectivity by forwarding
   packets destined to, or sent from, the mobile node.  In practice,
   most of the deployed architectures today have a small number of
   centralized anchors managing the traffic of millions of mobile nodes.
   Compared with a distributed approach, a centralized approach is
   likely to have several issues or limitations affecting performance
   and scalability, which require costly network dimensioning and
   engineering to resolve.

   To optimize handovers from the perspective of mobile nodes, the base
   protocols have been extended to efficiently handle packet forwarding
   between the previous and new points of attachment.  These extensions
   are necessary when applications have stringent requirements in terms
   of delay.  Notions of localization and distribution of local agents
   have been introduced to reduce signaling overhead [Paper-
   Distributed.Centralized.Mobility].  Unfortunately, today we witness
   difficulties in getting such protocols deployed, resulting in sub-
   optimal choices for the network operators.

   Moreover, the availability of multi-mode devices and the possibility
   of using several network interfaces simultaneously have motivated the
   development of even more protocol extensions to add more capabilities
   to the base protocol.  In the end, deployment is further complicated
   with the multitude of extensions.

   Mobile users are, more than ever, consuming Internet content; such
   traffic imposes new requirements on mobile core networks for data
   traffic delivery.  When the traffic demand exceeds available
   capacity, service providers need to implement new strategies such as
   selective traffic offload (e.g. 3GPP work items LIPA/SIPTO

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   [TS.23829]) through alternative access networks (e.g.  WLAN) [Paper-
   Mobile.Data.Offloading].  Moreover, the presence of content providers
   closer to the mobile/fixed Internet Service Providers network
   requires taking into account local Content Delivery Networks (CDNs)
   while providing mobility services.

   When demand exceeds capacity, both traffic offloading and CDN
   mechanisms could benefit from the development of mobile architectures
   with fewer levels of routing hierarchy introduced into the data path
   by the mobility management system.  This trend towards so-called
   "flat networks" is reinforced by a shift in user traffic behavior.
   In particular, there is an increase in direct communications among
   peers in the same geographical area.  Distributed mobility management
   in a truly flat mobile architecture would anchor the traffic closer
   to the point of attachment of the user, overcoming the suboptimal
   route stretch of a centralized mobility scheme.

   While deploying today's mobile networks, service providers face new
   challenges.  Mobility patterns indicate that, more often than not,
   mobile nodes remain attached to the same point of attachment for
   considerable periods of time [Paper-Locating.User] .  Therefore it is
   not uncommon to observe that specific IP mobility management support
   is not required for applications that launch and complete their
   sessions while the mobile node is connected to the same point of
   attachment.  However, currently, IP mobility support is designed for
   always-on operation, maintaining all parameters of the context for
   each mobile subscriber for as long as they are connected to the
   network.  This can result in a waste of resources and ever-increasing
   costs for the service provider.  Infrequent node mobility coupled
   with application intelligence suggest that mobility can be provided
   selectively, thus simplifying the context maintained in the different
   nodes of the mobile network.

   The DMM charter addresses two complementary aspects of mobility
   management procedures: the distribution of mobility anchors towards a
   more flat network and the dynamic activation/deactivation of mobility
   protocol support as an enabler to distributed mobility management.
   The former aims at positioning mobility anchors (HA, LMA) closer to
   the user; ideally, mobility agents could be collocated with the
   first-hop router.  The latter, facilitated by the distribution of
   mobility anchors, aims at identifying when mobility support must be
   activated and identifying sessions that do not require mobility
   management support -- thus reducing the amount of state information
   that must be maintained in various mobility agents of the mobile
   network.  The key idea is that dynamic mobility management relaxes
   some of the constraints of previously-standardized mobility
   management solutions and, by doing so, it can avoid the establishment
   of non-optimal tunnels between two topologically distant anchors.

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   Given this motivational background in this section, this document
   compares distributed mobility management with centralized mobility
   management in Section 3.  The requirements to address these problems
   are given in Section 4.  Finally, security considerations are
   discussed in Section 5.

   The problem statement and the use cases [I-D.yokota-dmm-scenario] can
   be found in [Paper-Distributed.Mobility.Review].

2.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
   document are to be interpreted as described in [RFC2119].

2.1.  Terminology

   All the general mobility-related terms and their acronyms used in
   this document are to be interpreted as defined in the Mobile IPv6
   base specification [RFC6275], in the Proxy mobile IPv6 specification
   [RFC5213], and in Mobility Related Terminology [RFC3753].  These
   terms include the following: mobile node (MN), correspondent node
   (CN), and home agent (HA) as per [RFC6275]; local mobility anchor
   (LMA) and mobile access gateway (MAG) as per [RFC5213], and context
   as per [RFC3753].

   In addition, this draft introduces the following term.

   Mobility context

      is the collection of information required to provide mobility
      management support for a given mobile node.

3.  Centralized versus distributed mobility management

   Mobility management functions may be implemented at different layers
   of the protocol stack.  At the IP (network) layer, they may reside in
   the network or in the mobile node.  In particular, a network-based
   solution resides in the network only.  It therefore enables mobility
   for existing hosts and network applications which are already in
   deployment but lack mobility support.

   At the IP layer, a mobility management protocol supporting session
   continuity is typically based on the principle of distinguishing
   between identifier and routing address and maintaining a mapping
   between the two.  In Mobile IP, the home address serves as an

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   identifier of the device whereas the care-of-address (CoA) takes the
   role of the routing address.  The binding between these two is
   maintained at the home agent (mobility anchor).  If packets can be
   continuously delivered to a mobile node at its home address, then all
   sessions using that home address are unaffected even though the
   routing address (CoA) changes.

   The next two subsections explain centralized and distributed mobility
   management functions in the network.

3.1.  Centralized mobility management

   In centralized mobility management, the mapping information between
   the persistent node identifier and the changing IP address of a
   mobile node (MN) is kept at a single mobility anchor.  At the same
   time, packets destined to the MN are routed via this anchor.  In
   other words, such mobility management systems are centralized in both
   the control plane and the data plane.

   Many existing mobility management deployments make use of centralized
   mobility anchoring in a hierarchical network architecture, as shown
   in Figure 1.  Examples of such centralized mobility anchors are the
   home agent (HA) and local mobility anchor (LMA) in Mobile IPv6
   [RFC6275] and Proxy Mobile IPv6 [RFC5213], respectively.  Current
   cellular networks such as the Third Generation Partnership Project
   (3GPP) UMTS networks, CDMA networks, and 3GPP Evolved Packet System
   (EPS) networks employ centralized mobility management too.  In
   particular, Gateway GPRS Support Node (GGSN) and Serving GPRS Support
   Node (SGSN) in the 3GPP UMTS hierarchical network, and the Packet
   data network Gateway (P-GW) and Serving Gateway (S-GW) in the 3GPP
   EPS network, respectively, act as anchors in a hierarchy.

          UMTS                3GPP SAE              MIP/PMIP
        +------+              +------+              +------+
        | GGSN |              | P-GW |              |HA/LMA|
        +------+              +------+              +------+
           /\                    /\                    /\
          /  \                  /  \                  /  \
         /    \                /    \                /    \
        /      \              /      \              /      \
       /        \            /        \            /        \
   +------+  +------+    +------+  +------+    +------+  +------+
   | SGSN |  | SGSN |    | S-GW |  | S-GW |    |MN/MAG|  |MN/MAG|
   +------+  +------+    +------+  +------+    +------+  +------+

   Figure 1.  Centralized mobility management.

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3.2.  Distributed mobility management

   Mobility management functions may also be distributed to multiple
   networks as shown in Figure 2, so that a mobile node in any of these
   networks may be served by a closeby mobility function (MF).

   +------+  +------+  +------+  +------+
   |  MF  |  |  MF  |  |  MF  |  |  MF  |
   +------+  +------+  +------+  +------+
                       | MN |

   Figure 2.  Distributed mobility management.

   Mobility management may be partially or fully distributed.  In the
   former case only the data plane is distributed.  Fully distributed
   mobility management implies that both the data plane and the control
   plane are distributed.  These different approaches are described in
   detail in [I-D.yokota-dmm-scenario].

   A distributed mobility management scheme for future flat IP-based
   mobile network architecture consisting of access nodes is proposed in
   [Paper-Distributed.Dynamic.Mobility].  Its benefits over centralized
   mobility management are shown through simulations in [Paper-
   Distributed.Centralized.Mobility].  Moreover, the (re)use and
   extension of existing protocols in the design of both fully
   distributed mobility management [Paper-Migrating.Home.Agents] [Paper-
   Distributed.Mobility.SAE] and partially distributed mobility
   management [Paper-Distributed.Mobility.PMIP] [Paper-
   Distributed.Mobility.MIP] have been reported in the literature.
   Therefore, before designing new mobility management protocols for a
   future flat IP architecture, it is recommended to first consider
   whether existing mobility management protocols can be extended to
   serve a flat IP architecture.

4.  Requirements

   After comparing distributed mobility management against centralized
   deployment in Section 3, this section states the requirements as

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4.1.  Distributed deployment

   REQ1:  Distributed deployment

          IP mobility, network access and routing solutions provided by
          DMM MUST enable distributed deployment for mobility management
          of IP sessions so that traffic does not need to traverse
          centrally deployed mobility anchors and thus can be routed in
          an optimal manner.

          Motivation: This requirement is motivated by current trends in
          network evolution: (a) it is cost- and resource-effective to
          cache and distribute content by combining distributed mobility
          anchors with caching systems (e.g., CDN); (b) the
          significantly larger number of mobile nodes and flows call for
          improved scalability; (c) single points of failure are avoided
          in a distributed system; (d) threats against centrally
          deployed anchors, e.g., home agent and local mobility anchor,
          are mitigated in a distributed system.

   This requirement addresses problems PS1, PS2, PS3, and PS4 in the

   PS1:  Non-optimal routes

         Routing via a centralized anchor often results in a longer
         route.  The problem is especially manifested when accessing a
         local server or servers of a Content Delivery Network (CDN).

   PS2:  Divergence from other evolutionary trends in network

         Centralized mobility management can become non-optimal with a
         flat network architecture.

   PS3:  Low scalability of centralized route and mobility context

         Setting up routes through a central anchor and maintaining
         mobility context for each MN therein requires more resources is
         more difficult to scale in a centralized design, thus reducing
         scalability.  Distributing the route maintenance function and
         the mobility context maintenance function among different
         network entities can increase scalability.

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   PS4:  Single point of failure and attack

         Centralized anchoring may be more vulnerable to single points
         of failures and attacks than a distributed system.  The impact
         of a successful attack on a system with centralized mobility
         management can be far greater as well.

4.2.  Transparency to Upper Layers when needed

   REQ2:  Transparency to Upper Layers when needed

          DMM solutions MUST provide transparent mobility support above
          the IP layer when needed.  Such transparency is needed, for
          example, when, upon change of point of attachment to the
          Internet, an application flow cannot cope with a change in the
          IP address.  Otherwise, support for maintaining a stable home
          IP address or prefix during handovers may be declined.

          Motivation: The motivation of this requirement is to enable
          more efficient use of network resources and more efficient
          routing by not maintaining context at the mobility anchor when
          there is no such need.

   This requirement addresses the problems PS5 as well as the other
   related problem O-PS1.

   PS5:  Wasting resources to provide mobility support to nodes that do
         not need such support

         IP mobility support is not always required, and not every
         parameter of mobility context is always used.  For example,
         some applications do not need a stable IP address during a
         handover to maintain IP session continuity.  Sometimes, the
         entire application session runs while the terminal does not
         change the point of attachment.

   O-PS1:  Mobility signaling overhead with peer-to-peer communication

           Wasting resources when mobility signaling (e.g., maintenance
           of the tunnel, keep alive, etc.) is not turned off for peer-
           to-peer communication.  Peer-to-peer communications have
           particular traffic patterns that often do not benefit from
           mobility support from the network.  Thus, the assoicated
           mobility support signaling (e.g., maintenance of the tunnel,
           keep alives, etc.) wastes network resources for no
           application gain.  In such a case, it is better to enable
           mobility support selectively.

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4.3.  IPv6 deployment

   REQ3:  IPv6 deployment

          DMM solutions SHOULD target IPv6 as the primary deployment
          environment and SHOULD NOT be tailored specifically to support
          IPv4, in particular in situations where private IPv4 addresses
          and/or NATs are used.

          Motivation: This requirement is to be inline with the general
          orientation of IETF work.  DMM deployment is foreseen in mid-
          to long-term horizon, when IPv6 is expected to be far more
          common than today.  It is also unnecessarily complex to solve
          this problem for IPv4, as we will not be able to use some of
          the IPv6-specific features/tools.

4.4.  Existing mobility protocols

   REQ4:  Existing mobility protocols

          A DMM solution SHOULD first consider reusing and extending
          IETF-standardized protocols before specifying new protocols.

          Motivation: Using IETF protocols is easier to deploy and to

4.5.  Compatibility

   REQ5:  Compatibility

          The DMM solution MUST be able to co-exist with existing
          network deployments and end hosts.  For example, depending on
          the environment in which DMM is deployed, DMM solutions may
          need to be compatible with other deployed mobility protocols
          or may need to interoperate with a network or mobile hosts/
          routers that do not support DMM protocols.  Furthermore, a DMM
          solution SHOULD work across different networks, possibly
          operated as separate administrative domains, when allowed by
          the trust relationship between them.

          Motivation: The motivations of this requirement are (1) to
          preserve backwards compatibility so that existing networks and
          hosts are not affected and continue to function as usual, and
          (2) enable inter-domain operation if desired.

   This requirement addresses the following related problem O-PS2.

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   O-PS2:  Complicated deployment with too many MIP variants and

           Deployment is complicated with many variants and extensions
           of MIP.  When introducing new functions which may add to the
           complexity, existing solutions are more vulnerable to break.

4.6.  Security considerations

   REQ6:  Security considerations

          DMM protocol solutions MUST consider security aspects,
          including confidentiality and integrity.  Examples of aspects
          to be considered are authentication and authorization
          mechanisms that allow a legitimate mobile host/router to use
          the mobility support provided by the DMM solution; signaling
          message protection in terms of authentication, encryption,
          etc.; data integrity and confidentiality; opt-in or opt-out
          data confidentiality to signaling messages depending on
          network environments or user requirements.

          Motivation: Mutual authentication and authorization between a
          mobile host/router and an access router providing the DMM
          service to the mobile host/router are required to prevent
          potential attacks in the access network of the DMM service.
          Various attacks such as impersonation, denial of service, man-
          in-the-middle attacks, and so on, can be mounted against a DMM
          service and need to be protected against.

          Signaling messages can be subject to various attacks since
          they carry critical context information about a mobile node/
          router.  For instance, a malicious node can forge a number of
          signaling messages thus redirecting traffic from its
          legitimate path.  Consequently, the specific node is under a
          denial of service attack, whereas other nodes do not receive
          their traffic.  As signaling messages may travel over the
          Internet, end-to-end security could be required.

5.  Security Considerations

   Distributed mobility management (DMM) requires two kinds of security
   considerations: First, access network security that only allows a
   legitimate mobile host/router to access the DMM service; Second, end-
   to-end security that protects signaling messages for the DMM service.
   Access network security is required between the mobile host/router
   and the access network providing the DMM service.  End-to-end
   security is required between nodes that participate in the DMM

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   It is necessary to provide sufficient defense against possible
   security attacks, or to adopt existing security mechanisms and
   protocols to provide sufficient security protections.  For instance,
   EAP-based authentication can be used for access network security,
   while IPsec can be used for end-to-end security.

6.  IANA Considerations


7.  Co-authors and Contributors

   This problem statement document is a joint effort among the following
   participants.  Each individual has made significant contributions to
   this work.

   Dapeng Liu:

   Pierrick Seite:

   Hidetoshi Yokota:

   Charles E. Perkins:

   Melia Telemaco:

   Elena Demaria:

   Peter McCann:

   Kostas Pentikousis:

   Tricci So:

   Jong-Hyouk Lee:

   Jouni Korhonen:

   Sri Gundavelli:

   Carlos J. Bernardos:

   Marco Liebsch:

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   Wen Luo:

   Georgios Karagiannis:

   Julien Laganier:

   Wassim Michel Haddad:

   Alexandru Petrescu:

   Seok Joo Koh:

   Dirk von Hugo:

   Ahmad Muhanna:

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

              Zhou, X., Korhonen, J., Williams, C., Gundavelli, S., and
              C. Bernardos, "Prefix Delegation for Proxy Mobile IPv6",
              draft-ietf-netext-pd-pmip-02 (work in progress),
              March 2012.

              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.

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

              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

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              (NTMS), 2008.

              Chan, H., "Distributed Mobility Management with Mobile
              IP",  Proceedings of  IEEE International Communication
              Conference (ICC)  Workshop on Telecommunications:  from
              Research to Standards, June 2012.

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

              Chan, H., Yokota, H., Xie, J., Seite, P., and D. Liu,
              "Distributed and Dynamic Mobility Management  in Mobile
              Internet: Current Approaches and Issues, Journal of
              Communications, vol. 6, no. 1, pp. 4-15, Feb 2011.",
               Proceedings of GlobeCom Workshop  on Seamless Wireless
              Mobility, February 2011.

              Fisher, M., Anderson, F., Kopsel, A., Schafer, G., and M.
              Schlager, "A Distributed IP Mobility Approach for 3G SAE",
               Proceedings of the 19th International Symposium  on
              Personal, Indoor and Mobile Radio Communications (PIMRC),

              Kirby, G., "Locating the User",  Communication
              International, 1995.

              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.

              Lee, K., Lee, J., Yi, Y., Rhee, I., and S. Chong, "Mobile
              Data Offloading: How Much Can WiFi Deliver?",  SIGCOMM
              2010, 2010.

   [RFC3753]  Manner, J. and M. Kojo, "Mobility Related Terminology",
              RFC 3753, June 2004.

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

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              RFC 3963, January 2005.

   [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.

   [RFC5944]  Perkins, C., "IP Mobility Support for IPv4, Revised",
              RFC 5944, November 2010.

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

   [RFC6301]  Zhu, Z., Wakikawa, R., and L. Zhang, "A Survey of Mobility
              Support in the Internet", RFC 6301, July 2011.

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

Author's Address

   H Anthony Chan (editor)
   Huawei Technologies
   5340 Legacy Dr. Building 3, Plano, TX 75024, USA
   Dapeng Liu
   China Mobile
   Unit2, 28 Xuanwumenxi Ave, Xuanwu District,  Beijing 100053, China
   Pierrick Seite
   France Telecom - Orange
   4, rue du Clos Courtel, BP 91226,  Cesson-Sevigne 35512, France
   Hidetoshi Yokota
   KDDI Lab
   2-1-15 Ohara, Fujimino, Saitama, 356-8502 Japan
   Jouni Korhonen
   Nokia Siemens Networks

Chan (Ed.)               Expires March 11, 2013                [Page 15]

Internet-Draft                  DMM-Reqs                  September 2012

   Charles E. Perkins
   Huawei Technologies
   Melia Telemaco
   Alcatel-Lucent Bell Labs
   Elena Demaria
   Telecom Italia
   via G. Reiss Romoli, 274, TORINO, 10148, Italy
   Jong-Hyouk Lee
   RSM Department, Telecom Bretagne
   Cesson-Sevigne, 35512, France
   Kostas Pentikousis
   Huawei Technologies
   Carnotstr. 4 10587 Berlin, Germany
   Tricci So
   Carlos J. Bernardos
   Universidad Carlos III de Madrid
   Av. Universidad, 30, Leganes, Madrid 28911, Spain
   Peter McCann
   Huawei Technologies
   Seok Joo Koh
   Kyungpook National University, Korea
   Wen Luo
   No.68, Zijinhua RD,Yuhuatai District, Nanjing, Jiangsu 210012, China
   Marco Liebsch
   NEC Laboratories Europe

Chan (Ed.)               Expires March 11, 2013                [Page 16]

Internet-Draft                  DMM-Reqs                  September 2012

   Carl Williams
   MCSR Labs

Chan (Ed.)               Expires March 11, 2013                [Page 17]