The Network Access Identifier
RFC 4282

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• 06

Network Working Group                                           B. Aboba
Request for Comments: 4282                                     Microsoft
Obsoletes: 2486                                               M. Beadles
Category: Standards Track                                       ENDFORCE
                                                                J. Arkko
                                                                Ericsson
                                                               P. Eronen
                                                                   Nokia
                                                           December 2005

                     The Network Access Identifier

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   In order to provide roaming services, it is necessary to have a
   standardized method for identifying users.  This document defines the
   syntax for the Network Access Identifier (NAI), the user identity
   submitted by the client during network authentication.  "Roaming" may
   be loosely defined as the ability to use any one of multiple Internet
   Service Providers (ISPs), while maintaining a formal, customer-vendor
   relationship with only one.  Examples of where roaming capabilities
   might be required include ISP "confederations" and ISP-provided
   corporate network access support.  This document is a revised version
   of RFC 2486, which originally defined NAIs.  Enhancements include
   international character set and privacy support, as well as a number
   of corrections to the original RFC.

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RFC 4282             The Network Access Identifier         December 2005

Table of Contents

   1. Introduction ....................................................2
      1.1. Terminology ................................................3
      1.2. Requirements Language ......................................4
      1.3. Purpose ....................................................4
   2. NAI Definition ..................................................4
      2.1. Formal Syntax ..............................................4
      2.2. NAI Length Considerations ..................................6
      2.3. Support for Username Privacy ...............................6
      2.4. International Character Sets ...............................7
      2.5. Compatibility with E-Mail Usernames ........................8
      2.6. Compatibility with DNS .....................................8
      2.7. Realm Construction .........................................8
      2.8. Examples ..................................................10
   3. Security Considerations ........................................10
   4. IANA Considerations ............................................11
   5. References .....................................................11
      5.1. Normative References ......................................11
      5.2. Informative References ....................................12
   Appendix A.  Changes from RFC 2486 ................................14
   Appendix B.  Acknowledgements .....................................14

1.  Introduction

   Considerable interest exists for a set of features that fit within
   the general category of "roaming capability" for network access,
   including dialup Internet users, Virtual Private Network (VPN) usage,
   wireless LAN authentication, and other applications.  Interested
   parties have included the following:

   o  Regional Internet Service Providers (ISPs) operating within a
      particular state or province, looking to combine their efforts
      with those of other regional providers to offer dialup service
      over a wider area.

   o  National ISPs wishing to combine their operations with those of
      one or more ISPs in another nation to offer more comprehensive
      dialup service in a group of countries or on a continent.

   o  Wireless LAN hotspots providing service to one or more ISPs.

   o  Businesses desiring to offer their employees a comprehensive
      package of dialup services on a global basis.  Those services may
      include Internet access as well as secure access to corporate
      intranets via a VPN, enabled by tunneling protocols such as the

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RFC 4282             The Network Access Identifier         December 2005

      Point-to-Point Tunneling Protocol (PPTP) [RFC2637], the Layer 2
      Forwarding (L2F) protocol [RFC2341], the Layer 2 Tunneling