Personal P. Roberts
Internet Draft J. Loughney
Category: Informational November 21, 2001
Expires: May 21, 2002
Local Subnet Mobility Problem Statement
<draft-proberts-local-subnet-mobility-problem-02.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.
Internet Draft Local Subnet Mobility Problem Statement Nov 21, 2001
Abstract.............................................................1
1. Introduction......................................................3
1.1 Scope of This Document.........................................3
1.2 Background......................................................3
2. Problems For Investigation........................................3
2.1 Problem One.....................................................4
2.2 Problem Two.....................................................4
2.3 Problem Three...................................................4
3. Next Steps........................................................5
4. Acknowledgements..................................................5
5. Addresses.........................................................5
6. References........................................................5
Roberts [Page 2]
Internet Draft Local Subnet Mobility Problem Statement Nov 21, 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.
1.1 Scope of This Document
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.
It is not the intention of this document to compete with other
mobility solutions, such as Mobile IP, but rather investigate
micromobility issues.
1.2 Background
A number of protocols have been proposed for micromobility such as
Cellular IP [CIP], Hawaii [HAW], EMA [EMA], etc.
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 as well, which directly lead to this
work.
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. Problems For Investigation
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?
Roberts [Page 3]
Internet Draft Local Subnet Mobility Problem Statement Nov 21, 2001
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 node's
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.
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
Roberts [Page 4]
Internet Draft Local Subnet Mobility Problem Statement Nov 21, 2001
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. Next Steps
To further the discussion on this subject, discussion on the
applicability of existing solutions the problems outlined in this
document could be useful. Additionally, clarification of the
problem space and terminology would be beneficial.
4. Acknowledgements
The authors of this work would like to be considered more as
compilers, rather than authors. They would like to acknowledge all
the contributors who have produced work relating to host routing for
the various problems.
Vince Park and Michael Thomas specifically contributed valuable text
for this problem statement.
5. Addresses
Phil Roberts
Megisto Systems, Inc.
proberts@megisto.com
John Loughney
Nokia
john.Loughney@nokia.com
6. References
[MC] M. Scott Corson, A. O'Neill, G. Tsirtsis. IP Fast
Restoration. Work in Progress. Draft-corson-
fastrestore-00.txt, November 2000.
[FHO] G. Tsirtsis, et. al. "Fast Handovers for Mobile
Ipv6." Work in Progress. Draft-ietf-mobileip-fast-
mipv6-02.txt, July 2001.
[MT] M. Thomas. "Analysis of Mobile IP and RSVP
Interactions." Work in Progress. Draft-thomas-
seamoby-rsvp-analysis-00.txt, February 2001.
Roberts [Page 5]
Internet Draft Local Subnet Mobility Problem Statement Nov 21, 2001
[CI] Z. Shelby, et. al. "Cellular IP v6." Work in
Progress. draft-shelby-seamoby-cellularipv6-01.txt,
July 2001.
[HSR] A. O'Neill. "Host Specific Routing." Work in
Progress. Draft-oneill-li-hst-00.txt, November 2000.
[IMMP] A. Campbell and J. Gomez. "IP Micro-mobility
Protocols." ACM SIGMOBILE Mobile Computer and
Communications Review (MC2R), 2001, available at
http://www.comet.columbia.edu/micromobility.
[CIP] Campbell, et. al. "Cellular IP." Work in Progress.
Draft expired, but available at
http://www.comet.columbia.edu/micromobility.
[HAW] Ramjee, et. al. "Hawaii." 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
Full Copyright Statement
Copyright (C) The Internet Society (2001). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
Roberts [Page 6]
Internet Draft Local Subnet Mobility Problem Statement Nov 21, 2001
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC editor function is currently provided by the
Internet Society.
Roberts [Page 7]