RFC4831: Goals for Network-Based Localized Mobility Management (NETLMM)

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Network Working Group                                      J. Kempf, Ed.
Request for Comments: 4831                               DoCoMo USA Labs
Category: Informational                                       April 2007


    Goals for Network-Based Localized Mobility Management (NETLMM)

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   In this document, design goals for a network-based localized mobility
   management (NETLMM) protocol are discussed.

Table of Contents

   1. Introduction ....................................................2
      1.1. Terminology ................................................2
   2. NETLMM Functional Architecture ..................................3
   3. Goals for the NETLMM Protocol ...................................3
      3.1. Goal 1: Handover Performance Improvement ...................4
      3.2. Goal 2: Reduction in Handover-Related Signaling Volume .....5
      3.3. Goal 3: Location Privacy ...................................6
      3.4. Goal 4: Limit Overhead in the Network ......................7
      3.5. Goal 5: Simplify Mobile Node Mobility Management
           Security by Deriving from IP Network Access and/or IP
           Movement Detection Security ................................7
      3.6. Goal 6: Link Technology Agnostic ...........................8
      3.7. Goal 7: Support for Unmodified Mobile Nodes ................8
      3.8. Goal 8: Support for IPv4 and IPv6 ..........................9
      3.9. Goal 9: Reuse of Existing Protocols Where Sensible ........10
      3.10. Goal 10: Localized Mobility Management
            Independent of Global Mobility Management ................10
      3.11. Goal 11: Configurable Data Plane Forwarding
            between Local Mobility Anchor and Mobile Access Gateway ..11
   4. Security Considerations ........................................11
   5. Acknowledgements ...............................................11
   6. Normative References ...........................................12
   7. Informative References .........................................12
   8. Contributors ...................................................13



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1.  Introduction

   In [1], the basic problems that occur when a global mobility protocol
   is used for managing local mobility are described, and two currently
   used approaches to localized mobility management -- the host-based
   approach that is used by most IETF protocols, and the proprietary
   Wireless LAN (WLAN) switch approach used between WLAN switches in
   different subnets -- are examined.  The conclusion from the problem
   statement document is that none of the approaches has a complete
   solution to the problem.  While the WLAN switch approach is most
   convenient for network operators and users because it requires no
   software on the mobile node other than the standard drivers for WiFi,
   the proprietary nature limits interoperability, and the restriction
   to a single last-hop link type and wired backhaul link type restricts
   scalability.  The IETF host-based protocols require host software
   stack changes that may not be compatible with all global mobility
   protocols.  They also require specialized and complex security
   transactions with the network that may limit deployability.  The
   conclusion is that a localized mobility management protocol that is
   network based and requires no software on the host for localized
   mobility management is desirable.

   This document develops a brief functional architecture and detailed
   goals for a network-based localized mobility management protocol
   (NETLMM).  Section 2 describes the functional architecture of NETLMM.
   In Section 3, a list of goals that is desirable in the NETLMM
   protocol is presented.  Section 4 briefly outlines Security
   Considerations.  More discussion of security can be found in the
   threat analysis document [2].

1.1.  Terminology

   Mobility terminology in this document follows that in RFC 3753 [10]
   and in [1].  In addition, the following terms are related to the
   functional architecture described in Section 2:

   Localized Mobility Management Domain

      An Access Network in the sense defined in [1] in which mobility is
      handled by the NETLMM protocol.

   Mobile Access Gateway

      A Mobile Access Gateway (MAG) is a functional network element that
      terminates a specific edge link and tracks mobile node IP-level
      mobility between edge links, through NETLMM signaling with the
      Localized Mobility Anchor.  The MAG also terminates host routed
      data traffic from the Localized Mobility Anchor for mobile nodes



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      currently located within the edge link under the MAG's control,
      and forwards data traffic from mobile nodes on the edge link under
      its control to the Localized Mobility Anchor.

   Local Mobility Anchor

      A Local Mobility Anchor (LMA) is a router that maintains a
      collection of host routes and associated forwarding information
      for mobile nodes within a localized mobility management domain
      under its control.  Together with the MAGs associated with it, the
      LMA uses the NETLMM protocol to manage IP node mobility within the
      localized mobility management domain.  Routing of mobile node data
      traffic is anchored at the LMA as the mobile node moves around
      within the localized mobility management domain.

2.  NETLMM Functional Architecture

   The NETLMM architecture consists of the following components.
   Localized Mobility Anchors (LMAs) within the backbone network
   maintain a collection of routes for individual mobile nodes within
   the localized mobility management domain.  The routes point to the
   Mobile Access Gateways (MAGs) managing the links on which the mobile
   nodes currently are located.  Packets for a mobile node are routed to
   and from the mobile node through tunnels between the LMA and MAG.
   When a mobile node moves from one link to another, the MAG sends a
   route update to the LMA.  While some mobile node involvement is
   necessary and expected for generic mobility functions such as
   movement detection and to inform the MAG about mobile node movement,
   no specific mobile-node-to-network protocol will be required for
   localized mobility management itself.  Host stack involvement in
   mobility management is thereby limited to generic mobility functions
   at the IP layer, and no specialized localized mobility management
   software is required.

3.  Goals for the NETLMM Protocol

   Section 2 of [1] describes three problems with using a global
   mobility management protocol for localized mobility management.  Any
   localized mobility management protocol must naturally address these
   three problems.  In addition, the side effects of introducing such a
   solution into the network need to be limited.  In this section, we
   address goals for NETLMM, including both solving the basic problems
   (Goals 1, 2, and 3) and limiting the side effects (Goals 4+).








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   Some basic goals of all IETF protocols are not discussed in detail
   here, but any solution is expected to satisfy them.  These goals are
   fault tolerance, robustness, interoperability, scalability, and
   minimal specialized network equipment.  A good discussion of their
   applicability to IETF protocols can be found in [4].

   Out of scope for the initial goals discussion are Quality of Service
   (QoS) and dormant mode/paging.  While these are important functions
   for mobile nodes, they are not part of the base localized mobility
   management problem.  In addition, mobility between localized mobility
   management domains is not covered here.  It is assumed that this is
   covered by the global mobility management protocols.

3.1.  Goal 1: Handover Performance Improvement

   Handover packet loss occurs because there is usually latency between
   when the link handover starts and when the IP subnet configuration
   and global mobility management signaling completes.  During this
   time, the mobile node is unreachable at its former topological
   location on the old link where correspondents are sending packets.
   Such misrouted packets are dropped.  This aspect of handover
   performance optimization has been the subject of much work, both in
   other Standards Development Organizations (SDOs) and in the IETF, in
   order to reduce the latency in IP handover.  Many solutions to this
   problem have been proposed at the link layer and at the IP layer.
   One aspect of this goal for localized mobility management is that the
   processing delay for changing the forwarding after handover must
   approach as closely as possible the sum of the delay associated with
   link-layer handover and the delay required for active IP-layer
   movement detection, in order to avoid excessive packet loss.
   Ideally, if network-side link-layer support is available for handling
   movement detection prior to link handover or as part of the link
   handover process, the routing update should complete within the time
   required for link handover.  This delay is difficult to quantify, but
   for voice traffic, the entire handover delay, including Layer 2
   handover time and IP handover time should be between 40-70 ms to
   avoid any degradation in call quality.  Of course, if the link-layer
   handover latency is too high, sufficient IP-layer handover
   performance for good real-time service cannot be matched.

   A goal of the NETLMM protocol -- in networks where the link-layer
   handover latency allows it -- is to reduce the amount of latency in
   IP handover, so that the combined IP-layer and link-layer handover
   latency is less than 70 ms.







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3.2.  Goal 2: Reduction in Handover-Related Signaling Volume

   Considering Mobile IPv6 [9] as the global mobility protocol (other
   mobility protocols require about the same or somewhat less), if a
   mobile node using address autoconfiguration is required to
   reconfigure on every move between links, the following signaling must
   be performed:

   1) Link-layer signaling required for handover and reauthentication.
      For example, in 802.11 [7], this is the Reassociate message
      together with 802.1x [8] reauthentication using EAP.

   2) Active IP-level movement detection, including router reachability.
      The Detecting Network Attachment (DNA) protocol [5] uses Router
      Solicitation/Router Advertisement for this purpose.  In addition,
      if SEcure Neighbor Discovery (SEND) [3] is used and the mobile
      node does not have a certificate cached for the router, the mobile
      node must use Certification Path Solicitation/Certification Path
      Advertisement to obtain a certification path.

   3) Two Multicast Listener Discovery (MLD) [14] REPORT messages, one
      for each of the solicited node multicast addresses corresponding
      to the link local address and the global address.

   4) Two Neighbor Solicitation (NS) messages for duplicate address
      detection, one for the link local address and one for the global
      address.  If the addresses are unique, no response will be
      forthcoming.

   5) Two NS messages from the router for address resolution of the link
      local and global addresses, and two Neighbor Advertisement
      messages in response from the mobile node.

   6) Binding Update/Binding Acknowledgement between the mobile node and
      home agent to update the care of address binding.

   7) Return routability signaling between the correspondent node and
      mobile node to establish the binding key, consisting of one Home
      Test Init/Home Test and Care of Test Init/Care of Test.

   8) Binding Update/Binding Acknowledgement between the correspondent
      node and mobile node for route optimization.

   Note that Steps 1-2 may be necessary, even for intra-link mobility,
   if the last-hop link protocol doesn't provide much help for IP
   handover.  Steps 3-5 will be different if stateful address
   configuration is used, since additional messages are required to
   obtain the address.  Steps 6-8 are only necessary when Mobile IPv6 is



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   used.  The result is approximately 18 messages at the IP level, where
   the exact number depends on various specific factors, such as whether
   or not the mobile node has a router certificate cached before a
   mobile node can be ensured that it is established on a link and has
   full IP connectivity.  In addition to handover related signaling, if
   the mobile node performs Mobile IPv6 route optimization, it may be
   required to renew its return routability key periodically (on the
   order of every 7 minutes), even if it is not moving, resulting in
   additional signaling.

   The signaling required has a large impact on the performance of
   handover, impacting Goal 1.  Perhaps more importantly, the aggregate
   impact from many mobile nodes of such signaling on expensive shared
   links (such as wireless where the capacity of the link cannot easily
   be expanded) can result in reduced last-hop link capacity for data
   traffic.  Additionally, in links where the end user is charged for IP
   traffic, IP signaling is not without cost.

   To address the issue of signaling impact described above, the goal is
   that handover signaling volume from the mobile node to the network
   should be no more than what is needed for the mobile node to perform
   secure IP-level movement detection, in cases where no link-layer
   support exists.  Furthermore, NETLMM should not introduce any
   additional signaling during handover beyond what is required for IP-
   level movement detection.  If link-layer support exists for IP-level
   movement detection, the mobile node may not need to perform any
   additional IP-level signaling after link-layer handover.

3.3.  Goal 3: Location Privacy

   In any IP network, there is a threat that an attacker can determine
   the physical location of a network node from the node's topological
   location.  Depending on how an operator deploys their network, an
   operator may choose to assign subnet coverage in a way that is
   tightly bound to geography at some timescale, or it may choose to
   assign it in ways in which the threat of someone finding a node
   physically based on its IP address is smaller.  Allowing the L2
   attachment and L3 address to be less tightly bound is one tool for
   reducing this threat to location privacy.

   Mobility introduces an additional threat.  An attacker can track a
   mobile node's geographical location in real-time, if the victim
   mobile node must change its IP address as it moves from one subnet to
   another through the covered geographical area.  If the granularity of
   the mapping between the IP subnets and geographical area is small for
   the particular link type in use, the attacker can potentially
   assemble enough information to find the victim in real time.




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   In order to reduce the risk from location privacy compromises as a
   result of IP address changes, the goal for NETLMM is to remove the
   need to change IP address as a mobile node moves across links in an
   access network.  Keeping the IP address fixed over a large
   geographical region fuzzes out the resolution of the mapping between
   the IP subnets and geographical area, regardless of how small the
   natural deployment granularity may be.  This reduces the chance that
   the attacker can deduce the precise geographic location of the mobile
   node.

3.4.  Goal 4: Limit Overhead in the Network

   Access networks, including both the wired and wireless parts, tend to
   have somewhat stronger bandwidth and router processing constraints
   than the backbone.  In the wired part of the network, these
   constraints are a function of the cost of laying fiber or wiring to
   the wireless access points in a widely dispersed geographic area.  In
   the wireless part of the network, these constraints are due to the
   limitation on the number of bits per Hertz imposed by the physical
   layer protocol.  Therefore, any solutions for localized mobility
   management should minimize overhead within the access network.

3.5.  Goal 5: Simplify Mobile Node Mobility Management Security by
      Deriving from IP Network Access and/or IP Movement Detection
      Security

   Localized mobility management protocols that have host involvement
   may require an additional security association between the mobile
   node and the mobility anchor, and establishing this security
   association may require additional signaling between the mobile node
   and the mobility anchor (see [13] for an example).  The additional
   security association requires extra signaling and therefore extra
   time to negotiate.  Reducing the complexity of mobile-node-to-network
   security for localized mobility management can therefore reduce
   barriers to deployment and improve responsiveness.  Naturally, such
   simplification must not come at the expense of maintaining strong
   security guarantees for both the network and mobile node.

   In NETLMM, the network (specifically, the MAG) derives the occurrence
   of a mobility event, requiring a routing update for a mobile node
   from link-layer handover signaling, or IP-layer movement detection
   signaling from the mobile node.  This information is used to update
   routing for the mobile node at the LMA.  The handover, or movement
   detection signaling, must provide the network with proper
   authentication and authorization so that the network can definitively
   identify the mobile node and determine its authorization.  The
   authorization may be at the IP level -- for example, using something
   like SEND [3] to secure IP movement detection signaling -- or it at



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   the link level.  Proper authentication and authorization must be
   implemented on link-layer handover signaling and/or IP-level movement
   detection signaling in order for the MAG to securely deduce mobile
   node movement events.  Security threats to the NETLMM protocol are
   discussed in [2].

   The goal is that security for NETLMM mobile node mobility management
   should derive from IP network access and/or IP movement detection
   security, such as SEND or network access authentication, and not
   require any additional security associations or additional signaling
   between the mobile node and the network.

3.6.  Goal 6: Link Technology Agnostic

   The number of wireless link technologies available is growing, and
   the growth seems unlikely to slow down.  Since the standardization of
   a wireless link physical and medium access control layers is a time-
   consuming process, reducing the amount of work necessary to interface
   a particular wireless link technology to an IP network is necessary.
   When the last-hop link is a wireless link, a localized mobility
   management solution should ideally require minimal work to interface
   with a new wireless link technology.

   In addition, an edge mobility solution should provide support for
   multiple wireless link technologies.  It is not required that the
   localized mobility management solution support handover from one
   wireless link technology to another without a change in the IP
   address, but this possibility should not be precluded.

   The goal is that the localized mobility management protocol should
   not use any wireless link specific information for basic routing
   management, though it may be used for other purposes, such as
   securely identifying a mobile node.

3.7.  Goal 7: Support for Unmodified Mobile Nodes

   In the WLAN switching market, no modification of the software on the
   mobile node is required to achieve localized mobility management.
   Being able to accommodate unmodified mobile nodes enables a service
   provider to offer service to as many customers as possible, the only
   constraint being that the customer is authorized for network access.

   Another advantage of minimizing mobile node software for localized
   mobility management is that multiple global mobility management
   protocols can be supported.  There are a variety of global mobility
   management protocols that might also need support, including
   proprietary or link technology-specific protocols needing support for
   backward compatibility reasons.  Within the Internet, both Host



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   Identity Protocol (HIP) [11] and IKEv2 Mobility and Multihoming
   (MOBIKE) [6] are likely to need support in addition to Mobile IPv6
   [9], and Mobile IPv4 [12] support may also be necessary.

   Note that this goal does NOT mean that the mobile node has no
   software at all associated with mobility.  The mobile node must have
   some kind of global mobility protocol if it is to move from one
   domain of edge mobility support to another and maintain session
   continuity, although no global mobility protocol is required if the
   mobile node only moves within the coverage area of the localized
   mobility management protocol or no session continuity is required
   during global movement.  Also, if the last-hop link is a wireless
   link, every wireless link protocol requires handover support on the
   mobile node in the physical and medium access control layers,
   typically in the wireless interface driver.  Information passed from
   the medium access control layer to the IP layer on the mobile node
   may be necessary to trigger IP signaling for IP handover.  Such
   movement detection support at the IP level may be required in order
   to determine whether the mobile node's default router is still
   reachable after the move to a new access point has occurred at the
   medium access control layer.  Whether or not such support is required
   depends on whether the medium access control layer can completely
   hide link movement from the IP layer.  For cellular type wireless
   link protocols, the mobile node and network undergo an extensive
   negotiation at the medium access control layer prior to handover, so
   it may be possible to trigger a routing update without any IP
   protocol involvement.  However, for a wireless link protocol such as
   IEEE 802.11 [7] in which the decision for handover is entirely in the
   hands of the mobile node, IP-layer movement detection signaling from
   the mobile node may be required to trigger a routing update.

   The goal is that the localized mobility management solution should be
   able to support any mobile node that joins the link and that has an
   interface that can communicate with the network, without requiring
   localized mobility management software on the mobile node.

3.8.  Goal 8: Support for IPv4 and IPv6

   While most of this document is written with IPv6 in mind, localized
   mobility management is a problem in IPv4 networks as well.  A
   solution for localized mobility that works for both versions of IP is
   desirable, though the actual protocol may be slightly different due
   to the technical details of how each IP version works.  From Goal 7
   (Section 3.7), minimizing mobile node support for localized mobility
   means that ideally no IP version-specific changes should be required
   on the mobile node for localized mobility, and that global mobility
   protocols for both IPv4 and IPv6 should be supported.  Any IP
   version-specific features should be confined to the network protocol.



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3.9.  Goal 9: Reuse of Existing Protocols Where Sensible

   Many existing protocols are available as Internet Standards upon
   which the NETLMM protocol can be built.  The design of the protocol
   should have a goal to reuse existing protocols where it makes
   architectural and engineering sense to do so.  However, the design
   should not attempt to reuse existing protocols where there is no real
   architectural or engineering reason.  For example, the suite of
   Internet Standards contains several good candidate protocols for the
   transport layer, so there is no real need to develop a new transport
   protocol specifically for NETLMM.  Reuse is clearly a good
   engineering decision in this case, since backward compatibility with
   existing protocol stacks is important.  On the other hand, the
   network-based, localized mobility management functionality being
   introduced by NETLMM is a new piece of functionality, and therefore
   any decision about whether to reuse an existing global mobility
   management protocol should carefully consider whether reusing such a
   protocol really meets the needs of the functional architecture for
   network-based localized mobility management.  The case for reuse is
   not so clear in this case, since there is no compelling backward
   compatibility argument.

3.10.  Goal 10: Localized Mobility Management Independent of Global
       Mobility Management

   Localized mobility management should be implementable and deployable
   independently of any global mobility management protocol.  This
   enables the choice of local and global mobility management to be made
   independently of particular protocols that are implemented and
   deployed to solve the two different sorts of mobility management
   problems.  The operator can choose a particular localized mobility
   management protocol according to the specific features of their
   access network.  It can subsequently upgrade the localized mobility
   management protocol on its own, without even informing the mobile
   nodes.  Similarly, the mobile nodes can use a global mobility
   management protocol that best suits their requirements, or not use
   one at all.  Also, a mobile node can move into a new access network
   without having to check that it understands the localized mobility
   management protocol being used there.

   The goal is that the implementation and deployment of the localized
   mobility management protocol should not restrict, or be restricted
   by, the choice of global mobility management protocol.








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3.11.  Goal 11: Configurable Data Plane Forwarding between Local
       Mobility Anchor and Mobile Access Gateway

   Different network operators may require different types of forwarding
   options between the LMA and the MAGs for mobile node data plane
   traffic.  An obvious forwarding option that has been used in past
   IETF localized mobility management protocols is IP-IP encapsulation
   for bidirectional tunneling.  The tunnel endpoints are the LMA and
   the MAGs.  But other options are possible.  Some network deployments
   may prefer routing-based solutions.  Others may require security
   tunnels using IPsec Encapsulating Security Payload (ESP)
   encapsulation if part of the localized mobility management domain
   runs over a public access network and the network operator wants to
   protect the traffic.

   A goal of the NETLMM protocol is to allow the forwarding between the
   LMA and MAGs to be configurable depending on the particulars of the
   network deployment.  Configurability is not expected to be dynamic,
   as in controlled by the arrival of a mobile node; but rather,
   configuration is expected to be similar in timescale to configuration
   for routing.  The NETLMM protocol may designate a default forwarding
   mechanism.  It is also possible that additional work may be required
   to specify the interaction between a particular forwarding mechanism
   and the NETLMM protocol, but this work is not in scope of the NETLMM
   base protocol.

4.  Security Considerations

   There are two kinds of security issues involved in network-based
   localized mobility management: security between the mobile node and
   the network, and security between network elements that participate
   in the NETLMM protocol.  The security-related goals in this document,
   described in Section 3.3 and 3.5, focus on the former, because those
   are unique to network-based mobility management. The threat analysis
   document [2] contains a more detailed discussion of both kinds of
   threats, which the protocol design must address.

5.  Acknowledgements

   The authors would like to acknowledge the following people for
   particularly diligent reviewing: Vijay Devarapalli, Peter McCann,
   Gabriel Montenegro, Vidya Narayanan, Pekka Savola, and Fred Templin.









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6.  Normative References

   [1]  Kempf, J., Ed., "Problem Statement for Network-Based Localized
        Mobility Management (NETLMM)", RFC 4830, April 2007.

   [2]  Vogt, C., and Kempf, J., "Security Threats to Network-Based
        Localized Mobility Management (NETLMM)", RFC 4832, April 2007.

7.  Informative References

   [3]  Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
        Neighbor Discovery (SEND)", RFC 3971, March 2005.

   [4]  Carpenter, B., "Architectural Principles of the Internet", RFC
        1958, June 1996.

   [5]  Choi, JH. and G. Daley, "Goals of Detecting Network Attachment
        in IPv6", RFC 4135, August 2005.

   [6]  Eronen, P., "IKEv2 Mobility and Multihoming Protocol (MOBIKE)",
        RFC 4555, June 2006.

   [7]  IEEE, "Wireless LAN Medium Access Control (MAC)and Physical
        Layer (PHY) specifications", IEEE Std. 802.11, 1999.

   [8]  IEEE, "Port-based Access Control", IEEE LAN/MAN Standard 802.1x,
        June, 2001.

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

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

   [11] Moskowitz, R. and P. Nikander, "Host Identity Protocol (HIP)
        Architecture", RFC 4423, May 2006.

   [12] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, August
        2002.

   [13] Soliman, H., Castelluccia, C., El Malki, K., and L. Bellier,
        "Hierarchical Mobile IPv6 Mobility Management (HMIPv6)", RFC
        4140, August 2005.

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





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8.  Contributors

   Kent Leung
   Cisco Systems, Inc.
   170 West Tasman Drive
   San Jose, CA 95134
   USA
   EMail: kleung@cisco.com

   Phil Roberts
   Motorola Labs
   Schaumberg, IL
   USA
   EMail: phil.roberts@motorola.com

   Katsutoshi Nishida
   NTT DoCoMo Inc.
   3-5 Hikarino-oka, Yokosuka-shi
   Kanagawa,
   Japan
   Phone: +81 46 840 3545
   EMail: nishidak@nttdocomo.co.jp

   Gerardo Giaretta
   Telecom Italia Lab
   via G. Reiss Romoli, 274
   10148 Torino
   Italy
   Phone: +39 011 2286904
   EMail: gerardo.giaretta@tilab.com

   Marco Liebsch
   NEC Network Laboratories
   Kurfuersten-Anlage 36
   69115 Heidelberg
   Germany
   Phone: +49 6221-90511-46
   EMail: marco.liebsch@ccrle.nec.de

Editor's Address

   James Kempf
   DoCoMo USA Labs
   181 Metro Drive, Suite 300
   San Jose, CA 95110
   USA
   Phone: +1 408 451 4711
   EMail: kempf@docomolabs-usa.com



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Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

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Kempf                        Informational                     [Page 14]