Mobile IPv4 Extension for Carrying Network Access Identifiers
RFC 3846

Network Working Group                                       F. Johansson
Request for Comments: 3846                                   ipUnplugged
Category: Standards Track                                   T. Johansson
                                                              Bytemobile
                                                               June 2004

     Mobile IPv4 Extension for Carrying Network Access Identifiers

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 (2004).

Abstract

   When a mobile node moves between two foreign networks, it has to be
   re-authenticated.  If the home network has both multiple
   Authentication Authorization and Accounting (AAA) servers and Home
   Agents (HAs) in use, the Home AAA server may not have sufficient
   information to process the re-authentication correctly (i.e., to
   ensure that the same HA continues to be used).  This document defines
   a Mobile IP extension that carries identities for the Home AAA and HA
   servers in the form of Network Access Identifiers (NAIs).  The
   extension allows a Home Agent to pass its identity (and that of the
   Home AAA server) to the mobile node, which can then pass it on to the
   local AAA server when changing its point of attachment.  This
   extension may also be used in other situations requiring
   communication of a NAI between Mobile IP nodes.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Requirements terminology . . . . . . . . . . . . . . . . . . .  2
   3.  NAI Carrying Extension . . . . . . . . . . . . . . . . . . . .  3
       3.1.  Processing of the NAI Carrying Extension . . . . . . . .  3
   4.  HA Identity subtype  . . . . . . . . . . . . . . . . . . . . .  4
   5.  AAAH Identity subtype  . . . . . . . . . . . . . . . . . . . .  4
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  5
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  5
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  6

Jhansson & Johansson        Standards Track                     [Page 1]
RFC 3846              MIPv4 Extension for AAA NAIs             June 2004

   9.  Normative References . . . . . . . . . . . . . . . . . . . . .  6
   10. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . .  7
   11. Full Copyright Statement . . . . . . . . . . . . . . . . . . .  8

1.  Introduction

   When building networks one would like to be able to have redundancy.
   In order to achieve this, one might place multiple AAA servers in one
   domain.  When a mobile node registers via a visited network, the
   authentication will be handled by one of the AAA servers in the home
   domain.  At a later point, when the mobile node moves to another
   visited domain it again has to be authenticated.  However, due to the
   redundancy offered by the AAA protocol, it can not be guaranteed that
   the authentication will be handled by the same AAAH server as the
   previous one, which can result in the new AAAH not knowing to which
   HA the session was assigned.  This document defines a Mobile IP
   extension which can be used to distribute the information needed to
   resolve this.

   Furthermore, the only information that is normally available about
   the home agent in the registration request is the IP address as
   defined in RFC 3344 [5].  Unfortunately this may not be enough since
   some AAA infrastructures (such as Diameter [6]) use realm based
   routing; such a AAA infrastructure needs to know the FQDN identity of
   the home agent to be able to correctly handle the assignment of the
   home agent.  A reverse DNS lookup would only disclose the identity of
   the Mobile IP interface for that HA IP address, which may or may not
   have a one-to-one correspondence with the home agent FQDN identity.
   This is a reason for the HA to also include its own identity in the
   registration reply.  The MIP v4 extension defined in this document
   also has a subtype defined by which this may be done.  The HA
   identity can then be included by the mobile node in later
   registration requests when changing the point of attachment.

2.  Requirements terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this