Personal P. Roberts
Compiler
Internet Draft
Title: draft-proberts-local-subnet-mobility-
problem-01.txt
Category: Informational May 2001
Expires : November 2001
Local Subnet Mobility Problem Statement
<draft-proberts-local-subnet-mobility-problem-01.txt>
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:
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at:
http://www.ietf.org/shadow.html.
Abstract
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.
1
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.
References
[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
2001.
[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
Research,
Technical Report, TR 2000-5. 2000. available at
http://www.isr.umd.edu/TechReports/ISR/2000/TR_2000-5/TR_2000-5.phtml
Addresses
The compiler of this document is:
Phil Roberts, Megisto Systems, Inc., proberts@megisto.com
Design Team 4