Network Discovery and Selection Problem
RFC 5113

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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.

Arkko, et al.                Informational                      [Page 1]
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

Arkko, et al.                Informational                      [Page 2]
RFC 5113                Network Discovery and SP            January 2008

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