Applicability Statement for IP Mobility Support
RFC 2005

Document Type RFC - Proposed Standard (October 1996; No errata)
Author Jim Solomon 
Last updated 2013-03-02
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Network Working Group                                         J. Solomon
Request for Comments: 2005                                      Motorola
Category: Standards Track                                   October 1996

            Applicability Statement for IP Mobility Support

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.


   As required by [RFC 1264], this report discusses the applicability of
   Mobile IP to provide host mobility in the Internet.  In particular,
   this document describes the key features of Mobile IP and shows how
   the requirements for advancement to Proposed Standard RFC have been

1. Protocol Overview

   Mobile IP provides an efficient, scalable mechanism for node mobility
   within the Internet.  Using Mobile IP, nodes may change their point-
   of-attachment to the Internet without changing their IP address.
   This allows them to maintain transport and higher-layer connections
   while moving.  Node mobility is realized without the need to
   propagate host-specific routes throughout the Internet routing
   fabric.  The protocol is documented in [MIP-PROTO].

   In brief, Mobile IP routing works as follows.  Packets destined to a
   mobile node are routed first to its home network -- a network
   identified by the network prefix of the mobile node's (permanent)
   home address.  At the home network, the mobile node's home agent
   intercepts such packets and tunnels them to the mobile node's most
   recently reported care-of address.  At the endpoint of the tunnel,
   the inner packets are decapsulated and delivered to the mobile node.
   In the reverse direction, packets sourced by mobile nodes are routed
   to their destination using standard IP routing mechanisms.

   Thus, Mobile IP relies on protocol tunneling to deliver packets to
   mobile nodes that are away from their home network.  The mobile
   node's home address is hidden from routers along the path from the
   home agent to the mobile node due to the presence of the tunnel.  The
   encapsulating packet is destined to the mobile node's care-of address

Solomon                     Standards Track                     [Page 1]
RFC 2005           Mobile IP Applicability Statement        October 1996

   -- a topologically significant address -- to which standard IP
   routing mechanisms can deliver packets.

   The Mobile IP protocol defines the following:

   - an authenticated registration procedure by which a mobile node
     informs its home agent(s) of its care-of address(es);

   - an extension to ICMP Router Discovery [RFC1256] which allows mobile
     nodes to discover prospective home agents and foreign agents; and

   - the rules for routing packets to and from mobile nodes, including
     the specification of one mandatory tunneling mechanism ([MIP-IPinIP])
     and several optional tunneling mechanisms ([MIP-MINENC] and

2. Applicability

   Mobile IP is intended to solve node mobility across changes in IP
   subnet.  It is just as suitable for mobility across homogeneous media
   as it is for mobility across heterogeneous media.  That is, Mobile IP
   facilitates node movement from one Ethernet segment to another as
   well as it accommodates node movement from an Ethernet segment to a
   wireless LAN.

   One can think of Mobile IP as solving the "macro" mobility management
   problem.  It is less well suited for more "micro" mobility management
   applications -- for example, handoff amongst wireless transceivers,
   each of which covers only a very small geographic area.  In this
   later situation, link-layer mechanisms for link maintenance (i.e.
   link-layer handoff) might offer faster convergence and less overhead
   than Mobile IP.

   Mobile IP scales to handle a large number of mobile nodes in the
   Internet.  Without route optimization as described in [MIP-OPTIM],
   however, the home agent is a potential load point when serving many
   mobile nodes.  When home agents become overburdened, additional home
   agents can be added -- and even dynamically discovered by mobile
   nodes -- using mechanisms defined in the Mobile IP documents.

   Finally, it is noted that mobile nodes are assigned (home) IP
   addresses largely the same way in which stationary hosts are assigned
   long-term IP addresses; namely, by the authority who owns them.
   Properly applied, Mobile IP allows mobile nodes to communicate using
   only their home address regardless of their current location.  Mobile
   IP, therefore, makes no attempt to solve the problems related to
   local or global, IP address, renumbering.

Solomon                     Standards Track                     [Page 2]
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