INTERNET-DRAFT Carl Williams, Editor
Internet Engineering Task Force DoCoMo USA Labs
Issued: June 28, 2002
Expires: December 28, 2002
Localized Mobility Management Requirements
<draft-ietf-mobileip-lmm-requirements-02.txt>
Status of This Memo
This document is an Internet-Draft and is in full conformance with
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Abstract
This document describes requirements for Localized Mobility
Management (LMM) for Mobile IP and Mobile Ipv6 protocols.
These requirements are intended to guide the design of a protocol
specification for LMM. Localized Mobility Management, in general,
introduces enhancements to Mobile IPv4 and Mobile IPv6 to
reduce the amount of latency in binding updates sent to the Home
Agent and, for route-optimization, Correspondent Nodes, upon
Care of Address change. In addition, LMM seeks to reduce the
amount of signaling over the global Internet when a mobile
node traverses within a defined local domain. The identified
requirements are essential for localized mobility management
functionality. They are intended to be used as a guide for
analysis on the observed benefits over the identified requirements
for architecting and deploying LMM schemes.
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Table of Contents
1.0 Introduction .................................................... 2
2.0 Terminology ..................................................... 4
3.0 Requirements .................................................... 5
3.1 Intra-domain mobility ........................................ 5
3.2 Security ..................................................... 5
3.3 Induced LMM functional requirement ........................... 6
3.4 Scalability, Reliability, and Performance .................... 6
3.5 Mobility Management Support .................................. 8
3.6 Auto-configuration capabilities for LMM constituents.......... 8
3.7 Interworking with IP routing infrastructure requirement....... 9
3.8 Sparse routing element population requirement ................ 9
3.9 Support for Mobile IPv6 Handover ............................. 9
3.10 Simple network design requirement ........................... 9
3.12 Stability ................................................... 10
3.13 QoS Requirements ............................................ 10
4.0 Acknowledgments ................................................. 10
5.0 References ...................................................... 11
6.0 Author's Addresses .............................................. 12
7.0 Full Copyright Statement ........................................ 12
1.0 Introduction
In order to meet the demands of real-time applications and the
expectations of future wireless users for service level quality
similar to the one of wireline users, base mobility management in
IP networks, and in particular Mobile IP and Mobile IPv6 is facing
a number of technical challenges in terms of performance and scalability.
These manifest themselves as increased latencies in the control
signaling between a Mobile Node and its peer entities, namely the
Home Agent (HA) and its Corresponding Nodes (CNs).
In the base Mobile IP protocol [6][2], movement between two subnets
requires that the Mobile Node obtain a new Care of Address in the
new subnet. This allows the Mobile Node to receive traffic on the
new subnet. In order for the routing change to become effective,
however, the Mobile Node must issue a binding update (also known in
Mobile IPv4 as a Home Agent registration) to the Home Agent so that
the Home Agent can change the routing from the previous subnet to
the new subnet. The binding update establishes a host route on the
Home Agent between the Mobile Node's Home Address and its new Care
of Address. In addition, if route optimization is in use [2], the
Mobile Node may also issue binding updates to Correspondent Nodes to
allow them to send traffic directly to the new Care of Address
rather than tunneling their traffic through the Home Agent.
Traffic destined for the Mobile Node is sent to the old Care of
Address and is, effectively, dropped until the Home Agent processes
the MIPv6 Binding Update or MIPv4 Home Agent Registration. If the
Mobile Node is at some geographical and topological distance away
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from the Home Agent and Correspondent Nodes, the amount of time
involved in sending the binding updates may be greater than 100
hundred milliseconds. This latency in routing update may cause
some packets for the Mobile Node to be lost at the old Access Router.
This problem has been called "Localized Mobility Management (LMM)".
Localized mobility management schemes allow the Mobile Node to continue
receiving traffic on the new subnet without any change in the Home Agent
or Correspondent Node binding. The latency involved in updating the Care
of Address bindings at far geographical and topological distances is
eliminated or reduced until such time as the Mobile Node is in a position
to manage the latency cost.
Having provided some motivation and brief summary of the underlying
principles of LMM, it is important to enumerate goals for LMM.
Goals for LMM:
- reduce the signaling induced by changes in the
point of attachment due to the movement of a host;
reduction in signaling delay will minimize
packet loss and possible session loss;
- reduce the usage of air-interface and network
resources for mobility;
- reduce the processing overhead at the peer nodes,
thereby improving protocol scalability;
- avoid or minimize the changes of, or impact to the
Mobile Node, Home Agent or the Correspondent Node;
- avoid creating single points of failure;
- simplify the network design and provisioning
for enabling LMM capability in a network;
- allow progressive LMM deployment capabilities.
Identifying a solid set of requirements that will render the
protocol internals, for some LMM scheme, robust enough to
cater for the aforementioned considerations becomes essential
in designing a widely accepted solution. The remainder of this
document present a set of requirements that encompass essential
considerations for the design of an LMM scheme. It is with this
foundation that we can seek to ensure that the resulting LMM
solution will best preserve the fundamental philosophies and
architectural principles of the Internet in practice today.
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2.0 Terminology
See [2] for additional terminology.
Administrative Domain A collection of networks under the same
administrative control and grouped together
for administrative purposes. [2]
Local Mobility The movement of an IP device without requiring
a change to its routable IP address seen by
the CN or HA. Although its point of attachment
may change during the move, the IP addresses used
to reach the device (both its home and globally
visible routable IP address) do not change.
Local Coverage Area A Local Coverage Area (LCA) contains one or more
(LCA) IP subnets. Within the LCA, the globally visible
routable IP address assigned to a Mobile Host or
Mobile Router serving a Mobile Network does not
change.
Local Mobility Agent A Mobile Node may use a Local Mobility Agent to
(LMA) carry out the local mobility mangement
functionality. The LMA functionality will reside
on router(s) within the Local Coverage Area.
Localized Mobility A method of moving an IP device without requiring
Management (LMM) a change to its routable IP address seen by
its peers, namely the MN's HA and its CNs,
in order to restrict the signaling area, thus
possibly reducing the amount of signaling.
Strong Authentication Techniques that permit entities to provide
evidence that they know a particular secret
without revealing the secret. [3]
3.0 LMM Requirements
This section describes the requirements of a LMM solution. The
requirements are relevant to both Mobile IPv4 and Mobile IPv6.
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3.1 Intra-domain mobility
LMM is introduced to minimize the signaling traffic to the Home Agent
and/or Correspondent Node(s) for intra-domain mobility (within an
Local Coverage Area). This is the fundamental reason for
introducing localized mobility management extensions to core Mobile
IPv6.
In the LMM infrastructure a Correspondent Node or Home Agent outside
the administration domain MUST always be able to address the mobile
host by the same IP address, so that from the point of view of hosts
outside the administration domain, the IP address of the mobile host
remains fixed regardless of any changes in the Mobile Node's subnet.
It is not the intent or goal for LMM to enter the intra-subnet
(intra AR) mobility problem space. See [4] for more information
on this specific problem space.
3.2 Security
3.2.1 LMM protocol MUST provide for "security provisioning" within the
respective local coverage area.
The security of exchanging LMM specific information and signaling MUST
be ensured. Security provisioning includes protecting the integrity,
confidentiality, and authenticity of the transfer of LMM specific
information within the administration domain. If applicable, replay
protection MUST exist mutually between the LMM agents.
3.2.2 LMM protocol MUST provide for the security provisioning to be
disabled.
In certain environments the security within the Local Coverage Area
may not be necessary, or it may be preferred to minimize the LMM protocol
overhead. This feature would be used at the network operator's own risk.
3.2.3 LMM protocol MUST NOT interfere with the security provisioning that
exists between the Home Agent and the Mobile Node.
3.2.4 LMM protocol MUST NOT interfere with the security provisioning that
exists between the Correspondent Node and the Mobile Node.
3.2.5 LMM protocol MUST NOT introduce new security holes or the possibility
for DOS-style attacks.
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3.2.6 An LMM scheme MUST provide support for security at the
level associated with routing. LMM SHOULD also ensure
that the network be able to maintain topological confidentiality
from visiting mobile nodes. That is to say that the LMM
scheme in use SHOULD NOT reveal the visited network's
topology to the Mobile Node.
3.3 Induced LMM functional requirements
3.3.1 Any Localized Mobility Management protocol MUST NOT inject
any additional functionality over base Mobility [6, 9] at the
Home Agent or any of its peer CNs. Thus, the LMM framework
MUST NOT add any modifications or extensions to the Correspondent
Node(s) and Home Agent. It is essential to minimize
the involvement of the Mobile Node in routing beyond what is in
the basic MIP and MIpv6 protocol. Preferences, load balancing, and
other complex schemes requiring heavy mobile node involvement
in the mobility management task SHOULD BE avoided.
3.3.2 Non-LMM-aware routers, hosts, Home Agents, and Mobile Nodes
MUST be able to interoperate with LMM agents.
3.3.3 The LMM framework MUST NOT increase the number of messages between
the mobile host and the respective Correspondent Node(s) and Home
Agent. Indeed, the LMM framework MUST minimize the global
signaling between the MN and its peers. The amount
of regional signaling MUST NOT surpass the amount of global
signaling that would have otherwise occurred if LMM were not
present.
3.4 Scalability, Reliability, and Performance
3.4.1 The LMM complexity MUST increase at most linearly with the
size of the local domain and the number of Mobile Nodes.
3.4.2 Any Localized Mobility Management protocol MUST assure that
that LMM routing state scales at most linearly with the number
of Mobile Nodes registered, and that the increase in routing
state is confined to those ARs/ANRs involved in implementing
the LMM protocol at hand. This would involve MIP-specific
routing state as binding caches in addition to standard
routing table host routes. While host routes cannot be
eliminated by any mobility management protocol including
base IP mobility, any LMM protocol MUST keep the number of
host routes to a minimum.
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3.4.3 The LMM framework MUST NOT create single points of failure in
the network. The current access router would be excluded from
this requirement.
3.4.4 The LMM framework MUST NOT interfere with the basic IP mobility
performance of a mobile host communications with a Correspondent
Node(s).
3.4.5 Scalable expansion of the network
The LMM framework MUST allow for scalable expansion of the network
and provide for reasonable network configuration with regard
to peering, inter-administrative domain connectivity, and other
inter-administrative domain interoperability characteristics of
interest to wireless ISPs. The LMM framework MUST NOT introduce
any additional restrictions in how wireless ISPs configure their
network, nor how they interconnect with other networks beyond
those introduced by standard IP routing. In addition, the
amount of regional signaling MUST NOT increase as the Local
Domain expands in size.
3.4.6 Resilience to topological changes
The LMM protocols MUST be topology-independent. The LMM protocols
MUST be able to adapt to topological changes within the domain. The
topological changes may include the addition or removal/failure of
LMM agents or that of changes in the routing of the local domain
over which the LMM scheme is applied.
3.4.7 Header or Tunneling overhead
Any additional header or tunneling overhead caused by LMM MUST
be reduced on the radio link by compression. The transfer of
compressor state on movement SHOULD be possible so as not to
introduce any perceived service disruption.
Candidate LMM designs that require additional header overhead for
tunnels MUST be reviewed by the ROHC working group to determine
if the header compressor can be restarted from transferred compressor
context when handover occurs without requiring any full header packet
exchange on the new link.
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3.4.8 Optimized signaling within the Local Coverage Area
By its very nature, LMM reintroduces triangle routing into Mobile IPv6
in that all traffic must go through the LMM agent. There is no way
to avoid this. The LMM framework SHOULD be designed in such a way
as to reduce the length of the unwanted triangle leg.
The LMM design SHOULD not prohibit optimal placement of LMM agents to
reduce or eliminate additional triangle routing introduced by LMM.
NOTE: It is not required that a LMM scheme specify LMM agents as part
of its solution.
3.5 Mobility Management Support
The following LMM requirements pertain to both inter-domain and
intra-domain hand-off.
3.5.1 The LMM framework MUST NOT increase the amount of latency or amount of
packet loss that exists with the core Mobile IP and Mobile IPv6
specification [6, 9]. Indeed, the LMM framework SHOULD decrease the
amount of latency or amount of packet loss that exists with the
core mobility protocols.
3.5.2 The LMM framework MUST NOT increase the amount of service disruption
that already exists with the core mobility specifications.
Again, the LMM framework SHOULD decrease the amount of service
disruption that already exists with the core mobility protocols.
3.5.3 The LMM framework MUST NOT increase the number of messages between
the mobile host and the respective Correspondent Node(s) and Home
Agent as is in the core mobility specifications [6, 9]. The LMM
framework SHOULD decrease the number of messages between the
mobile host and the respective Correspondent Node(s) and Home
Agent as is in the core mobility specifications [6, 9].
3.6 Auto-configuration capabilities for LMM constituents
It is desirable that in order to allow for simple incremental
deployment of an LMM scheme, the local mobility agents MUST
require minimal (if any) manual configuration. This plug-and-play
feature could make use of IPv6 auto-configuration mechanisms in
the case of Mobile IPv6 [6], even though most likely other
automatic configurations will be needed (such as, for example,
learning about adjacent LMM agents). Auto-configuration also
facilitates the network to dynamically adapt to general topological
changes (whether planned or due to link or node failures).
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3.7 LMM inter-working with IP routing infrastructure requirement
The LMM framework MUST NOT disrupt core IP routing outside
the local domain.
3.8 Sparse routing element population requirement
Any LMM protocol MUST be designed to be geared towards
incremental deployment capabilities; the latter implies
that the LMM scheme itself imposes minimum requirements
on the carriers network. Incremental deployment capabilities
for an LMM protocol signifies that an initial set of sparse
LMM agents can populate the administration domain of a network
provider and operate sufficiently. In addition, any LMM
scheme MUST be compatible with any additional deployment
of LMM agents in future infrastructure expansions; that is to
say, allow progressive LMM deployment capabilities.
It is for this reason that the LMM framework MUST NOT require
that all routing elements be assumed to be LMM-aware in the
signaling interactions of an LMM protocol. The LMM framework
MUST BE supported, at the very minimum, by a sparse (proper
subset) LMM agent population that is co-located within the
routing topology of a single administration domain.
3.9 Support for Mobile IPv4 or Mobile IPv6 Handover
Since one of the primary goals of LMM is to minimize
signaling during handover, an LMM solution MUST be
available for the standardized Mobile IPv4 or Mobile IPv6
handover algorithms. LMM and the Mobile IP or Mobile IPv6
handover algorithms MUST maintain compatibility in their
signaling interactions for fulfilling complementary roles
with respect to each other.
This requirement SHOULD NOT be interpreted as ruling out
useful optimizations of LMM and Mobile IP or Mobile IPv6 handoff
schemes that simplify the implementation or deployment of LMM or
Mobile IP or Mobile IPv6 handoff.
3.10 Simple Network design requirement
LMM SHOULD simplify the network design and provisioning for enabling LMM
capability in a network and allow progressive LMM deployment capabilities.
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3.12 Stability
LMM MUST avoid any routing loops.
3.13 Quality of Service requirements
3.13.1 The LMM MUST have the ability to interwork with the
QoS schemes to hide the mobility of the MN to its peer
by avoiding end-to-end QoS signaling.
3.13.2 The LMM MUST have the ability to interwork with the QoS
schemes to facilitate the new provisioning of both uplink
and downlink QoS after a handoff.
4.0 Acknowledgments
Thank you to all who participated in the LMM requirement discussion
on the Mobile IP working group alias. First, I want to recognize
Theo Pagtzis's (University College London) work on LMM requirement
analysis. Theo has contributed significantly to the LMM discussion
on the mailing list and at IETF working group meetings and has
provided text for various requirements and the text for the
introduction detailing motivation and basic LMM principles. Theo's
work on requirement analysis will be published soon (see [1] below).
Special thanks also to John Loughney (Nokia), Alper Yegin
(DoCoMo USA Labs) and Madjid Nakhjiri (Motorola) for providing input
to the draft in its preliminary stage. As editor of the draft a small
team was put together to work with me on LMM requirement analysis:
Hesham Soliman (Ericsson), Erik Nordmark (Sun), Theo Pagtzis (UCL),
James Kempf (DoCoMo USA Labs), and Jari Malinen (Nokia).
Many other working group members have participated in the requirement
analysis of LMM for IPv6. This included writing requirements listed
in this document as well as providing insight into requirement
analysis. This made my job as editor of this document quite easy.
Members who contributed are:
Charlie Perkins (Nokia), Theo Pagtzis (University College London),
Muhammad Jaseemuddin (Nortel), Tom Weckstr (Helsinki University),
Jim Bound (Compaq), Erik Nordmark (Sun), James Kempf (DoCoMo USA Labs),
Gopal Dommety (Cisco), Glenn Morrow (Nortel), Arthur Ross (IEEE),
Samita Chakrabarti (Sun), Hesham Soliman (Ericsson),
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Karim El-Malki (Ericsson), Phil Neumiller (Telocity), Behcet Sarikaya
(Alcatel), Karann Chew (University of Surrey), Michael Thomas (Cisco),
Pat Calhoun (Black Storm Networking), Bill Gage (Nortel Networks),
Vinod Choyi (Alcatel), John Loughney (Nokia), Wolfgang Schoenfeld
(GMD IPSI), and David Martin (Nextel). Recent comments received
by Atsushi Takeshita (DoCoMo USA Labs), Daichi Funato (DoCoMo USA
Labs), Youngjune Gwon (DoCoMo USA Labs), Ichiro Okajima (NTT DoCoMo),
Jari Malinen (Nokia), Kacheong Poon (DoCoMo USA Labs)
and Koshimi Takashi (NTT DoCoMo). Thanks to
Cedric Westphal (Nokia) for a thorough reviewing of the draft.
In addition special thanks to the Mobile IP working group chairs
for their input as well as capturing and organizing the initial set
of requirements from the discussions, Phil Roberts (Magisto) and
Basavaraj Patil (Nokia).
5.0 References
[1] Theo Pagtzis, "Requirements for Localized Mobility
Management in IPv6 Networks"; Paper in Submission;
Work In Progress, November 2001.
[2] Manner, J. et al; "Mobility Related Terminology";
draft-manner-seamoby-terms-02.txt; Work In
Progress; July 2001.
[3] J.J. Tardo and K. Alagappan, "SPX: Global Authentication
Using Public Key Certificates." In Proc IEEE Symp.
Research in Security and Privacy. IEEE CS Press, 1991.
[4] Roberts, P., "Local Subnet Mobility Problem Statement";
draft-proberts-local-subnet-mobility-problem-01.txt;
Work In Progress; May 2001.
[5] Perkins, C., "IP Mobility Support". IETF,
Request for Comments (RFC) 2002, October 1996.
[6] David B. Johnson, Charles Perkins, "Mobility Support
in IPv6"; draft-ietf-mobileip-ipv6-14.txt; July 2001.
[7] Tsirtsis, G. (Editor), "Fast Handovers for Mobile
IPv6"; draft-ietf-mobileip-fast-mipv6-00.txt; a work
in progress; February 2001.
[8] Loughney, J. (Editor), "SeaMoby Micro Mobility Problem
Statement"; draft-ietf-seamoby-mm-problem-01.txt; a work
in progress; February 2001.
[9] Perkins, C., "IP Mobility Support for IPv4," RFC3220,
January 2002.
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6.0 Authors' Addresses
The working group can be contacted via the current chairs:
Basavaraj Patil Phil Roberts
Nokia Corporation Megisto Systems
6000 Connection Drive 20251 Century Blvd
Irving, TX 75039 Suite 120
USA Germantown Maryland, 20874-1191
Phone: +1 972-894-6709 EMail: proberts@megisto.com
EMail: Raj.Patil@nokia.com
Fax : +1 972-894-5349
Questions about this memo can also be directed to:
Carl Williams
DoCoMo Communications Laboratories USA, Inc.
181 Metro Drive, Suite 300
San Jose, CA 95110
USA
phone: +1 408 451 4741
fax: +1 408 573 1090
email: carlw@docomolabs-usa.com
7.0 Full Copyright Statement
Copyright (C) The Internet Society (2000). 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.
This document and the information contained herein is provided on an
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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
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Carl Williams, Editor Expires December 28, 2002 [Page 12]
