Architectural Approaches to Multi-homing for IPv6
RFC 4177
Network Working Group G. Huston
Request for Comments: 4177 APNIC
Category: Informational September 2005
Architectural Approaches to Multi-homing for IPv6
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This memo provides an analysis of the architectural aspects of
multi-homing support for the IPv6 protocol suite. The purpose of
this analysis is to provide a taxonomy for classification of various
proposed approaches to multi-homing. It is also an objective of this
exercise to identify common aspects of this domain of study, and also
to provide a framework that can allow exploration of some of the
further implications of various architectural extensions that are
intended to support multi-homing.
Huston Informational [Page 1]
RFC 4177 Multi6 Architecture September 2005
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. The Multi-Homing Space . . . . . . . . . . . . . . . . . . . . 5
4. Functional Goals and Considerations . . . . . . . . . . . . . 7
5. Approaches to Multi-Homing . . . . . . . . . . . . . . . . . . 7
5.1. Multi-Homing: Routing . . . . . . . . . . . . . . . . . 8
5.2. Multi-Homing: Mobility . . . . . . . . . . . . . . . . . 9
5.3. Multi-homing: Identity Considerations . . . . . . . . . 12
5.4. Multi-homing: Identity Protocol Element . . . . . . . . 14
5.5. Multi-homing: Modified Protocol Element . . . . . . . . 15
5.6. Modified Site-Exit and Host Behaviors . . . . . . . . . 16
6. Approaches to Endpoint Identity . . . . . . . . . . . . . . . 17
6.1. Endpoint Identity Structure . . . . . . . . . . . . . . 18
6.2. Persistent, Opportunistic, and Ephemeral Identities . . 20
6.3. Common Issues for Multi-Homing Approaches . . . . . . . 23
6.3.1. Triggering Locator Switches . . . . . . . . . . 23
6.3.2. Locator Selection . . . . . . . . . . . . . . . 26
6.3.3. Layering Identity . . . . . . . . . . . . . . . 27
6.3.4. Session Startup and Maintenance . . . . . . . . 29
6.3.5. Dynamic Capability Negotiation . . . . . . . . . 31
6.3.6. Identity Uniqueness and Stability . . . . . . . 31
7. Functional Decomposition of Multi-Homing Approaches . . . . . 32
7.1. Establishing Session State . . . . . . . . . . . . . . . 32
7.2. Re-homing Triggers . . . . . . . . . . . . . . . . . . . 33
7.3. Re-homing Locator Pair Selection . . . . . . . . . . . . 33
7.4. Locator Change . . . . . . . . . . . . . . . . . . . . . 34
7.5. Removal of Session State . . . . . . . . . . . . . . . . 34
8. Security Considerations . . . . . . . . . . . . . . . . . . . 34
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 34
10. Informative References . . . . . . . . . . . . . . . . . . . . 34
Huston Informational [Page 2]
RFC 4177 Multi6 Architecture September 2005
1. Introduction
The objective of this analysis is to allow various technical
proposals relating to the support of multi-homing environment in IPv6
to be placed within an architectural taxonomy. This is intended to
allow these proposals to be classified and compared in a structured
fashion. It is also an objective of this exercise to identify common
aspects across all proposals within this domain of study, and also to
provide a framework that can allow exploration of some of the further
implications of various architectural extensions that are intended to
support multi-homing. The scope of this study is limited to the IPv6
protocol suite architecture, although reference is made to IPv4
approaches as required.
2. Terminology
Care-of Address (CoA)
A unicast routeable address associated with a mobile node while
visiting a foreign link; the subnet prefix of this IP address is a
foreign subnet prefix. Among the multiple care-of addresses that
a mobile node may have at any given time (e.g., with different
subnet prefixes), the one registered with the mobile node's home
agent for a given home address is called its "primary" care-of
address.
Correspondent Node (CN)
A peer node with which a mobile node is communicating. The
correspondent node may be either mobile or stationary.
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