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Mobile IPv6 Extensions (mext)                                 C. Perkins
Internet-Draft                                                   Tellabs
Intended status: Informational                               Dapeng. Liu
Expires: April 30, 2012                                     China Mobile
                                                            Oct 28, 2011


                         DMM Comparison Matrix
                      draft-perkins-dmm-matrix-02

Abstract

   Distributed Mobility Management (DMM) is proposed as a way to enable
   scalable growth of mobile core networks so that network service
   providers can meet new requirements for performance and reduced
   operational expenditures.  This requires reconsideration of existing
   approaches within the IETF and elsewhere in order to determine which
   if any such approaches may be used as part of a DMM solution.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 30, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Matrix Comparing Existing Approaches for DMM . . . . . . . . .  4
   3.  Explanations for Matrix Entries  . . . . . . . . . . . . . . .  5
     3.1.  Route Optimization . . . . . . . . . . . . . . . . . . . .  5
     3.2.  Source address selection refinements . . . . . . . . . . .  6
     3.3.  Dynamically allocated home agent . . . . . . . . . . . . .  7
     3.4.  Binding updates to CN even without HA  . . . . . . . . . .  8
     3.5.  Transport protocol Mobility  . . . . . . . . . . . . . . .  8
     3.6.  Local anchor . . . . . . . . . . . . . . . . . . . . . . .  9
     3.7.  HIP/LISP . . . . . . . . . . . . . . . . . . . . . . . . . 10
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   6.  Normative References . . . . . . . . . . . . . . . . . . . . . 11
   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . . 11
































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1.  Introduction

   The goal of this document is to identify and compare known existing
   approaches for Distributed Mobility Management (DMM).
   Characterizations of each of the various methods selected for
   comparison are provided in a matrix form according to whether or not
   they meet certain criteria.

   Efforts within the IETF have been launched to find improved mobility
   management by decentralizing some or all of the traditional functions
   associated with mobility, including handovers, location management,
   identification, and so on.

   The following abbreviations appear in this document:

      MN: mobile node

      HA: home agent

      CN: correspondent node

      FQDN: Fully Qualified Domain Name

   The following approaches to mobility management are characterized:

      Route optimization (RO): MN supplies Binding Updates directly to
      CN.[RFC3775]

      Source address selection refinements (SAddrSel): MN picks source
      address appropriate for current point of attachment when launching
      an application.

      Dynamically allocated home agent (DynHA): Mobility anchor for MN
      is allocated on demand.

      Binding updates to CN even without HA (CN-wo-HA): Similar to RO,
      but does not require protocol signaling with home agent.

      Transport protocol (Trans-Mob) : MN modifies transport (e.g., TCP,
      SCTP, DCCP, MPTCP) protocol parameters to change the IP address of
      transport connection endpoint

      Local anchor (Anchor-Mob): Local mobility anchor (e.g., MAP in
      HMIP [RFC5380]) available for use by MN at its current point of
      attachment.






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      Dynamic DNS (DynDNS): When MN gets a new address, DNS is updated
      so that the MN's FQDN resolves to that new address.

   The approaches listed above will be characterized according to the
   following criteria:

   1.  scalability: in # of nodes

   2.  specified?: whether there is a working group document specifying
       the approach

   3.  IPadd continuity: provides stable IP address

   4.  backhaul friendly: reduces burden on backhaul

   5.  app friendly: apps do not require new code

   6.  server-friendly: server state minimized, servers do not require
       new code

   7.  local routing: "local breakout" / "hairpinning" / local traffic
       routed locally

   8.  low signaling: not too much signaling required







2.  Matrix Comparing Existing Approaches for DMM

   The following matrix rates the approaches described in the the
   previous section according to the characteristics listed.
















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                     RO  SAddr DynHA  CN   Trans  Anchor DynDNS HIP/
                          Sel        wo-HA  Mob    Mob    Mob   LISP

   scalability        Y    Y     M     Y     Y      M      M     Y

   specified?         Y    N     N     N     Y      Y      Y     Y

   IPadd continuity   Y    N     N     Y     Y      Y      N     Y

   backhaul friendly  Y    Y     Y     Y     Y      M      Y     M

   app friendly       Y    N     Y     Y     N      Y      M    N/Y

   server-friendly    M    Y     Y     Y     N      Y      Y    N/Y

   local routing      Y    Y     M     Y     Y      N      Y     M

   low signaling      N    Y     M     N     N      N      N     N

        Table 1: Comparison Matrix [Legend: Y=Yes, N=No, M=Maybe]

3.  Explanations for Matrix Entries

   Most of the matrix entries are relatively self-evident.  For
   instance, "Trans Mob" (Transport-based Mobility) approaches are rated
   as not "app friendly" because applications require changes in order
   to make use of the approach.

   For approaches that are identified generically, it may be ambiguous
   whether or not they are properly specified in any working group
   document.  Here, such approaches are characterized as specified if
   any particular approach in the generic family is specified.  More
   detail may be needed in the future, in which case more columns or a
   new table may be needed.

3.1.  Route Optimization

   Mobile IPv6 supports route optimization and bi-directional tunneling.
   Using route optimization, the mobile node can send mobility
   signalling, and subsequently data packets, directly to the
   correspondent node.  The following aspects of route optimization are
   characterized in the comparison matrix.

   1.  Scalability: Using route optimization, the signalling and data do
       not have to be sent through the centralized mobility anchor.
       Since the effect of route optimization is to reduce traffic
       through the home network, scalability is improved.  Moreover,
       route optimization can reduce the effect of the home agent as a



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       single point of failure.

   2.  Specified: RFC 3775 specifies the route optimization mode of
       MIPv6.

   3.  IP address continuity: In MIPv6 route optimization mode, the
       mobile node still uses the same home address as the bi-
       directional tunnel mode.  RO mode supports IP address continuity.

   4.  backhaul friendly: In RO mode, the data can send directly to the
       CN.  Data do not need to send through centralized moblity anchor,
       thence RO is backhaul friendly.

   5.  app friendly: RO mode does not require application changing, so
       it is application friendly.

   6.  server-friendly: RO mode requires the server (i.e., CN) to also
       support Mobile IP RO mode.  In this sense, RO is not server
       friendly.

   7.  local routing: In RO mode, the data is forwarded directly between
       MN and CN, it thence can support local routing.

   8.  low signaling: MIPv6 RO mode use the return routability
       procedure. which requires more signalling than MIPv6 bi-
       directional tunnel mode.

3.2.  Source address selection refinements

   Source address selection refinements (SAddrSel): MN picks source
   address appropriate for current point of attachment when launching an
   application.

   1.  Scalability: Since the MN can pick a local source address,
       packets to/from the MN do not have to traverse the home network,
       improving scalability and reducing delay.

   2.  Specified: see [RFC3484]

   3.  IP address continuity: If the MN uses a local source address, IP
       address continuity is likely to be violated when MN moves to a
       new network where that address is no longer addressable.

   4.  backhaul friendly: Since packets do not have to traverse the home
       network, this solution is more backhaul friendly.

   5.  app friendly: since applications are likely to require changes in
       order to make the address selection, this solution is less app-



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       friendly.  If source addresses are selected without involvement
       of the application, this effect would be eliminated.

   6.  server-friendly: The source address selection by the application
       does not involve the server.

   7.  local routing: Using a local source address enables local routing
       for local services and communication partners.

   8.  low signaling: This solution does not impose any signaling
       signaling requirement, unless the address selection algorithm
       requires policy management by the operator.

3.3.  Dynamically allocated home agent

   Dynamically allocated home agent (DynHA): Mobility anchor for MN is
   allocated on demand.

   Scalability: If the network supports dynamically allocated home
   agents, the mobile node can choose the nearest home agent.  Other
   mobile nodes can use different home agents.  But when changing
   location, home agent may not be able to change accordingly.  The
   mechanism for associating home agents to mobile nodes can vary, and
   different algorithms have different scalability characteristics; some
   may be more scalable than others.  Method relying on anycast
   addresses for home agents are among the more scalable approaches.

   Specified: RFC 3775 specifies dynamic home agent address discovery
   and dynamic home prefix discovery.  But it does not support changing
   home agent afterwards.  If the MN selected a new home agent, it is
   likely that existing communications through the previous home agent
   would be disrupted.

   IP address continuity: When mobile node changes location, it may
   choose a new home agent, but home address would also need to change
   accordingly, making IP address continuity unlikely.

   backhaul friendly: The mobile node can choose the nearest home agent,
   in this sense, it is backhaul friendly.

   app friendly: application does not need to change to support
   dynamically allocated home agent.  So it is app friendly.

   server-friendly: server does not need to change to support
   dynamically allocated home agent, so it is server friendly.

   Local routing: When mobile node selects the nearest home agent, it
   can support local routing through that home agent.



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   Low signaling: Dynamic discovery and assignment of a home agent may
   need additional signaling.

3.4.  Binding updates to CN even without HA

   Binding updates to CN even without HA (CN-wo-HA): Similar to route
   optimization, but does not require protocol signaling with home
   agent.

   1.  Scalability: yes, same as for route optimization.

   2.  Specified: Internet drafts exist, but no working group document.

   3.  IP address continuity: yes, same as for route optimization.

   4.  backhaul friendly: yes, same as for route optimization.

   5.  app friendly: yes, same as for route optimization.

   6.  server-friendly: no, same as for route optimization.

   7.  local routing: yes, same as for route optimization.

   8.  low signaling: no, same as for route optimization.

3.5.  Transport protocol Mobility

   Transport protocol (Trans-Mob): MN modifies transport (e.g., TCP,
   SCTP, DCCP, MPTCP) protocol parameters to change the IP address of
   transport connection endpoint.  In many ways, such approaches
   resemble CN-wo-HA except that the signaling occurs at a different
   layer of the protocol stack (namely, at the transport layer instead
   of the network layer).

   1.  Scalability: yes, same as for CN-wo-HA.

   2.  Specified: no, same as for CN-wo-HA.

   3.  IP address continuity: The point of such approaches is,
       basically, to eliminate the need for IP address continuity.  So,
       while IP address continuity is not provided, this should not be
       considered a demerit of transport mobility approaches.  It would
       be better to compare approaches based on "session continuity"
       instead of "IP address continuity".

   4.  backhaul friendly: yes, same as for CN-wo-HA.





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   5.  app friendly: yes (typically), same as for CN-wo-HA.

   6.  server-friendly: no, same as for CN-wo-HA.

   7.  local routing: yes, same as for CN-wo-HA.

   8.  low signaling: MIPv6 RO mode use the return routability
       procedure. which requires more signalling than MIPv6 bi-
       directional tunnel mode.

3.6.  Local anchor

   Local anchor (Anchor-Mob): Local mobility anchor (e.g., MAP in HMIP
   [RFC5380]) available for use by MN at its current point of
   attachment.

   1.  Scalability: The mobile node signals the nearest anchor.  MNs in
       other networks can use different anchors.  Scalability is
       improved because the signaling path between the mobile node and
       its local anchor is shorter.  Moreover, local mobility anchors
       offload work from any remote mobility anchor such as the home
       agent.

   2.  Specified: HMIP[RFC5380]

   3.  IP address continuity: In conjunction with Mobile IPv6 as a macro
       mobility protocol, IP address continuity is enabled.

   4.  backhaul friendly: The mobile node can choose the nearest local
       anchor; in this sense, it is backhaul friendly.

   5.  app friendly: application does not need to change to support
       dynamically allocated home agent.  So it is app friendly.

   6.  server-friendly: server does not need to change to support local
       mobility anchor, so it is server friendly.

   7.  Local routing: Generally, the use of a local anchor does not
       necessarily improve local routing; additional functionality would
       need to be designed or included with the local anchor.

   8.  Low signaling: Additional signaling is required for the mobile
       node to insert new bindings at the local anchor.








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3.7.  HIP/LISP

   HIP: Host Identity Protocol(RFC 4423); LISP: Locator/ID Separation
   Protocol.

   1.  Scalability: HIP/LISP are both location/indentification
       separation protocol.  Both HIP/LISP can support large scale
       deployment in HIP/LISP domain.  But when a node running HIP/LISP
       needs to communicate with other hosts that are not located in the
       HIP/LISP domain, another mechanism is needed.

   2.  HIP is specified in RFC 4423[RFC5380].  LISP is specified in
       [I-D.ietf-lisp].

   3.  IP address continuity: HIP/LISP both use host indentification for
       addressing.  The host can use a stable IP address for
       identification and addressing, thence HIP/LISP can support IP
       address continuity.

   4.  backhaul friendly: HIP/LISP both use routing address for packet
       routing; there is no centralized anchor point in the data plane.
       But for communication to other hosts which are not located in the
       HIP/LISP domain, a gateway function is needed and the data
       traffic is constrained to travel through the gateway.

   5.  app friendly: LISP does not require application modification.
       HIP may require application modification [RFC 6317].

   6.  server-friendly: For mobile nodes, HIP may require server
       modifications; LISP does not require server modification.

   7.  Local routing: For communication within the HIP/LISP domain, HIP/
       LISP can support local routing since the routing is based on
       routing prefix instead of host indentification and there is no
       centralized anchor point.

   8.  Low signaling: HIP/LISP need new signaling in the host/network to
       support its function.

4.  Security Considerations

   This document does not have any security considerations.

5.  IANA Considerations

   This document does not have any IANA actions.





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6.  Normative References

   [I-D.ietf-lisp]  Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,
                    "Locator/ID Separation Protocol (LISP)",
                    draft-ietf-lisp-15 (work in progress), July 2011.

   [RFC3484]        Draves, R., "Default Address Selection for Internet
                    Protocol version 6 (IPv6)", RFC 3484, February 2003.

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

   [RFC4423]        Moskowitz, R. and P. Nikander, "Host Identity
                    Protocol (HIP) Architecture", RFC 4423, May 2006.

   [RFC5380]        Soliman, H., Castelluccia, C., ElMalki, K., and L.
                    Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
                    Management", RFC 5380, October 2008.

Appendix A.  Acknowledgements

   This document has benefitted from discussions with the following
   people, in no particular order: Seok Joo Koh, Jouni Korhonen, Julien
   Laganier, Dapeng Liu, Telemaco Melia, Pierrick Seite

Authors' Addresses

   Charles E. Perkins
   Tellabs

   Phone: +1-408-421-1172
   EMail: charliep@computer.org


   Dapeng Liu
   China Mobile

   Phone: +86-123-456-7890
   EMail: liudapeng@chinamobile.com












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