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Versions: 00 01 02                                                      
   Personal                                                P. Roberts
   Internet Draft
   Title: draft-proberts-local-subnet-mobility-
   Category: Informational                                  May 2001
   Expires : November 2001

                        Local Subnet Mobility Problem Statement

   Status of This Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
   and its working groups.  Note that other groups may also distribute
   working documents as Internet-Drafts.

   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."

   The list of current Internet-Drafts can be accessed at:
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   This document specifies a problem statement for investigation within
   the IRTF.  There are a couple of seemingly unrelated problems that
   have led investigators to converge on the desirability of
   implementing a routing protocol whose purpose is to allow a mobile
   node to retain connectivity via its current IP subnet while it moves
   within the scope of the micro mobility domain. In general this domain
   is expected to be contained within an autonomous system so that
   global aggregation of subnets is still preserved. An additional
   benefit of the protocols is that mobile nodes may more quickly react
   to failed links.  The problem is to investigate the limits and issues
   with using (a) new protocol(s) to implement per node routes to
   facilitate better the movement of nodes and recovery of the network
   in the presence of failed links or routers.  The document is a brief
   statement of the problem to be investigated with references to lots
   of other work that has been done already by many others in the area.

Internet Draft Local Subnet Mobility Problem Statement       May 2001

1. Introduction

   The design of Internet routing has evolved largely based on the
   assumption that most end systems are stationary. As the idea of
   mobile devices came along, Mobile IP provided an easy migration path
   for supporting end system mobility without significant change or
   impact to the Internet infrastructure. This was achieved primarily by
   placing the support for routing to mobile devices on the end systems
   and at a limited number of centralized points within the
   infrastructure, effectively "hiding" the end system mobility from the
   infrastructure routing protocols. However, as we anticipate the
   desire to support real-time traffic flows to mobile devices and the
   possibility that mobile devices may become a significant portion of
   all Internet end nodes, investigation of alternative designs merit
   consideration. Many investigators in this area have converged on
   solutions that propose the use of local subnet mobility routing to
   support mobility within a limited domain, effectively exposing the
   mobility of end systems to the routers.

   This draft represents a problem statement to enable investigation of
   how a local subnet mobility routing protocol can be employed to
   enable mobility and fast network recovery.  It is a problem statement
   based on a lot of work done in attempting to provide low latency
   handover in mobile networks and fast recovery in networks with fast
   recovery requirements.  Please see the reference list for a large set
   of work that has been done in the past along these lines.

   A good summary of the problem as it pertains to network recovery is
   [MC].  The micromobility design team of the seamoby working group
   produced a problem statement also [SMM].  See the reference list for
   lots of previous work that has been done especially in the area of
   mobility with alternate proposals from Mobile IP.

2. Problem Statement

   This section proposes questions that have led to a perceived need for
   investigation of node routing within the IRTF.  Why is there a
   perceived need for a non-tunnel-based routing solution for mobility?
   While Mobile IP provides transparency of the mobility to
   correspondent nodes communicating with hosts on the mobile network,
   Mobile IP does not provide transparency for any state contained
   within routers along the paths from correspondent nodes and the
   mobile node's home agent. That is, state in routers which is
   dependent on the stability of the source or destination address in
   the IP header will be negatively impacted by the mobile nodeÆs change
   of care of addresses. For example, when a mobile node changes its
   care of address, the mobile node's current reservation would require
   that the filter specs be updated with the new care of address. By
   instead treating the mobility as a topology change within the local
   area, these unpleasant second order effects can be avoided.

Design Team                                                          2
Internet Draft Local Subnet Mobility Problem Statement       May 2001

2.1 Problem One

   There are applications that involve supporting real-time traffic
   flows to end devices that are mobile.  These applications require
   that there be minimal (ideally no) interruption to the packet flows
   and that these flows need to preserve the existing QoS and security
   characteristics as the end station moves.  In addition the movement
   of the end devices should not cause excessive signaling in the
   network as the devices move.  Such applications often also run on
   networks in which link failures or router failures can cause a
   significant service disruption.  Is it possible to use a similar
   protocol to allow for faster restoration of service during link
   failures.  Could such mobility requirements and fast restoration
   requirements be met in a way that is more efficient and simpler than
   approaches based on Mobile IP and current intradomain routing
   protocols by using a routing protocol that implements local subnet
   mobility within a limited scope within the network?  What would the
   limits of such a solution be in terms of scaling?  Specifically how
   many nodes could be supported across what kind of network breadth and
   depth at what cost of complexity in the routers around the edge of
   such a network?  Is it possible to meet traffic engineering
   requirements using such a protocol?  Could it simplify management of
   QoS in the part of the network where mobility is most readily felt?

2.2 Problem Two

   One of the primary principles of the Internet has been end-to-end
   communication. Most (if not all) of the protocols running over IP
   have been designed with end-to-end signaling in mind.  Currently,
   changes due to mobility induce unwanted end-to-end signaling. This
   may cause applications running over IP to fail due to delay and
   latency induced by unwanted signaling.  Security, QoS and AAA
   signaling all suffer due to this.  Could a local subnet mobility
   protocol aid in this respect?

2.3 Problem Three

   Why is there a need for an investigation of it in the IRTF rather
   than a direct move to work on a standard within a working group of
   the IETF?  The area directors overseeing the activities of the
   seamoby working group and the mobile-ip working group have raised
   questions about the scale of local subnet mobility routing and the
   potential need to introduce both another routing protocol and another
   mobility protocol. A comparison with existing mobility management and
   routing protocols are involved in making such an assessment both in
   terms of relative scalability, performance, and complexity.

3. Acknowledgements

   The compiler would like to acknowledge all the contributors who have
   produced work relating to host routing for the various problems.  .

Design Team                                                          3
Internet Draft Local Subnet Mobility Problem Statement       May 2001

   John Loughney, Vince Park, and Michael Thomas contributed valuable
   text for this problem statement.


    [MC] M. Scott Corson, A. OÆNeill, G. Tsirtsis.  IP Fast Restoration.
Work in Progress.  Draft-corson-fastrestore-00.txt, November 2000.
    [SMM] J. Loughney, et. al.  ôSeaMoby Micromobility Problem
Statement.ö  Work in Progress.  Draft-ietf-seamoby-mm-problem-01.txt,
February 2001.
    [FHO] G. Tsirtsis, et. al.  ôFast Handovers for Mobile Ipv6.ö  Work
in Progress.  Draft-ietf-mobileip-fast-mipv6-00.txt, February 2001.
    [MT] M. Thomas.  ôAnalysis of Mobile IP and RSVP Interactions.ö
Work in Progress.  Draft-thomas-seamoby-rsvp-analysis-00.txt, February
    [CI] Z. Shelby, et. al.  ôCellular IP v6.ö  Work in Progress.
Draft-shelby-seamoby-cellularipv6-00.txt, November 2000.
    [HSR] A. OÆNeill.  ôHost Specific Routing.ö  Work in Progress.
Draft-oneill-li-hst-00.txt, November 2000.
    [IMMP] A. Campbell and J. Gomez.  ôIP Micro-mobility Protocols.ö
ACM SIGMOBILE Mobile Computer and Communications Review (MC2R), 2001,
available at http://www.comet.columbia.edu/micromobility.
    [CIP] Campbell, et. al.  ôCellular IP.ö  Work in Progress.  Draft
expired, but available at http://www.comet.columbia.edu/micromobility.
    [HAW] Ramjee, et. al.  ôHawaii.ö  Work in Progress.  Draft expired,
but available at http://www.comet.columbia.edu/micromobility.
    [EMA] M. Scott Corson, and Alan O'Neill. An Approach to Fixed/Mobile
   Converged Routing. University of Maryland, Institute for Systems
   Technical Report, TR 2000-5. 2000. available at


   The compiler of this document is:

   Phil Roberts, Megisto Systems, Inc., proberts@megisto.com

Design Team                                                          4