RFC 3846 (rfc3846) - Page 2 of 8

Mobile IPv4 Extension for Carrying Network Access Identifiers

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
   document are to be interpreted as described in BCP 14, RFC 2119 [1].

   The Mobile IP related terminology described in RFC 3344 [5] is used
   in this document.  In addition, the following terms are used:

   AAAH
      One of several possible AAA Servers in the Home Network






Jhansson & Johansson        Standards Track