RFC 2344 (rfc2344) - Page 1 of 19

Reverse Tunneling for Mobile IP

Network Working Group                              G. Montenegro, Editor
Request for Comments: 2344                        Sun Microsystems, Inc.
Category: Standards Track                                       May 1998


                    Reverse Tunneling for Mobile IP

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 (1998).  All Rights Reserved.

Abstract

   Mobile IP uses tunneling from the home agent to the mobile node's
   care-of address, but rarely in the reverse direction.  Usually, a
   mobile node sends its packets through a router on the foreign
   network, and assumes that routing is independent of source address.
   When this assumption is not true, it is convenient to establish a
   topologically correct reverse tunnel from the care-of address to the
   home agent.

   This document proposes backwards-compatible extensions to Mobile IP
   in order to support topologically correct reverse tunnels.  This
   document does not attempt to solve the problems posed by firewalls
   located between the home agent and the mobile node's care-of address.

Table of Contents

   1. Introduction ................................................   2
   1.1. Terminology ...............................................   3
   1.2. Assumptions ...............................................   4
   1.3. Justification .............................................   4
   2. Overview ....................................................   4
   3. New Packet Formats ..........................................   5
   3.1. Mobility Agent Advertisement Extension ....................   5
   3.2. Registration Request ......................................   5
   3.3. Encapsulating Delivery Style Extension ....................   6
   3.4. New Registration Reply Codes ..............................   7
   4. Changes in Protocol Behavior ................................   8
   4.1. Mobile Node Considerations ................................   8



Montenegro                  Standards Track