Network Discovery and Selection Problem
RFC 5113
Network Working Group J. Arkko
Request for Comments: 5113 Ericsson
Category: Informational B. Aboba
Microsoft
J. Korhonen, Ed.
TeliaSonera
F. Bari
AT&T
January 2008
Network Discovery and Selection Problem
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.
Abstract
When multiple access networks are available, users may have
difficulty in selecting which network to connect to and how to
authenticate with that network. This document defines the network
discovery and selection problem, dividing it into multiple sub-
problems. Some constraints on potential solutions are outlined, and
the limitations of several solutions (including existing ones) are
discussed.
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RFC 5113 Network Discovery and SP January 2008
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology Used in This Document . . . . . . . . . . . . 4
2. Problem Definition . . . . . . . . . . . . . . . . . . . . . . 7
2.1. Discovery of Points of Attachment . . . . . . . . . . . . 8
2.2. Identity Selection . . . . . . . . . . . . . . . . . . . . 9
2.3. AAA Routing . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.1. The Default Free Zone . . . . . . . . . . . . . . . . 13
2.3.2. Route Selection and Policy . . . . . . . . . . . . . . 14
2.3.3. Source Routing . . . . . . . . . . . . . . . . . . . . 15
2.4. Network Capabilities Discovery . . . . . . . . . . . . . . 17
3. Design Issues . . . . . . . . . . . . . . . . . . . . . . . . 18
3.1. AAA Routing . . . . . . . . . . . . . . . . . . . . . . . 18
3.2. Backward Compatibility . . . . . . . . . . . . . . . . . . 18
3.3. Efficiency Constraints . . . . . . . . . . . . . . . . . . 19
3.4. Scalability . . . . . . . . . . . . . . . . . . . . . . . 19
3.5. Static Versus Dynamic Discovery . . . . . . . . . . . . . 21
3.6. Security . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.7. Management . . . . . . . . . . . . . . . . . . . . . . . . 22
4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 23
5. Security Considerations . . . . . . . . . . . . . . . . . . . 25
6. Informative References . . . . . . . . . . . . . . . . . . . . 26
Appendix A. Existing Work . . . . . . . . . . . . . . . . . . . . 32
A.1. IETF . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
A.2. IEEE 802 . . . . . . . . . . . . . . . . . . . . . . . . . 33
A.3. 3GPP . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
A.4. Other . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 37
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1. Introduction
Today, network access clients are typically pre-configured with a
list of access networks and corresponding identities and credentials.
However, as network access mechanisms and operators have
proliferated, it has become increasingly likely that users will
encounter networks for which no pre-configured settings are
available, yet which offer desired services and the ability to
successfully authenticate with the user's home realm. It is also
possible that pre-configured settings will not be adequate in some
situations. In such a situation, users can have difficulty in
determining which network to connect to, and how to authenticate to
that network.
The problem arises when any of the following conditions are true:
o Within a single network, more than one network attachment point is
available, and the attachment points differ in their roaming
arrangements, or access to services. While the link layer
capabilities of a point of attachment may be advertised, higher-
layer capabilities, such as roaming arrangements, end-to-end
quality of service, or Internet access restrictions, may not be.
As a result, a user may have difficulty determining which services
are available at each network attachment point, and which
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