Low-Latency Handoffs in Mobile IPv4
RFC 4881

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Network Working Group                                   K. El Malki, Ed.
Request for Comments: 4881                                       Athonet
Category: Experimental                                         June 2007

                  Low-Latency Handoffs in Mobile IPv4

Status of This Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   Mobile IPv4 describes how a Mobile Node can perform IPv4-layer
   handoffs between subnets served by different Foreign Agents.  In
   certain cases, the latency involved in these handoffs can be above
   the threshold required for the support of delay-sensitive or real-
   time services.  The aim of this document is to present two methods to
   achieve low-latency Mobile IPv4 handoffs.  In addition, a combination
   of these two methods is described.  The described techniques allow
   greater support for real-time services on a Mobile IPv4 network by
   minimizing the period of time when a Mobile Node is unable to send or
   receive IPv4 packets due to the delay in the Mobile IPv4 Registration
   process.

Table of Contents

   1. Introduction ....................................................3
      1.1. Terminology ................................................4
      1.2. The Techniques .............................................5
      1.3. L2 Triggers ................................................7
      1.4. Requirements Language ......................................9
   2. Requirements ....................................................9
   3. The PRE-REGISTRATION Handoff Method ............................10
      3.1. Operation .................................................11
      3.2. Network-Initiated Handoff .................................13
      3.3. Mobile-Initiated Handoff ..................................15
      3.4. Obtaining and Proxying nFA Advertisements .................17
           3.4.1. Inter-FA Solicitation ..............................17
           3.4.2. Tunneled nFA Advertisements ........................18
      3.5. Caching Router Advertisements .............................19

El Malki, Ed.                 Experimental                      [Page 1]
RFC 4881            Low-Latency Mobile IPv4 Handoffs           June 2007

      3.6. Movement Detection, MN, and FA Considerations .............19
      3.7. L2 Address Considerations .................................21
      3.8. Applicability of PRE-REGISTRATION Handoff .................21
   4. The POST-REGISTRATION Handoff Method ...........................23
      4.1. Two-Party Handoff .........................................24
      4.2. Three-Party Handoff .......................................28
      4.3. Renewal or Termination of Tunneling Service ...............34
      4.4. When Will the MN Perform a Mobile IPv4 Registration? ......34
      4.5. Handoff Request (HRqst) Message Format ....................36
      4.6. Handoff Reply (HRply) Message Format ......................38
      4.7. Handoff to Third (HTT) Message Format .....................40
      4.8. Applicability of POST-REGISTRATION Handoff Method .........40
   5. Combined Handoff Method ........................................41
   6. Layer 2 and Layer 3 Handoff Timing Considerations ..............42
   7. Reverse Tunneling Support ......................................42
   8. Handoff Signaling Failure Recovery .............................43
      8.1. PRE-REGISTRATION Signaling Failure Recovery ...............43
           8.1.1. Failure of PrRtSol and PrRtAdv .....................43
           8.1.2. Failure of Inter-FA Solicitation and
                  Advertisement ......................................44
      8.2. POST-REGISTRATION Signaling Failure Recovery ..............44
           8.2.1. HRqst Message Dropped ..............................44
           8.2.2. HRply Message Dropped ..............................45
   9. Generalized Link Layer and IPv4 Address (LLA) Extension ........46
      9.1. 3GPP2 IMSI Link Layer Address and Connection ID
           Extension .................................................47
      9.2. 3GPP IMSI Link Layer Address Extension ....................48
      9.3. Ethernet Link Layer Address Extension .....................49
      9.4. IEEE 64-Bit Global Identifier (EUI-64) Address Extension ..50
      9.5. Solicited IPv4 Address Extension ..........................51
      9.6. Access Point Identifier Extension .........................52
      9.7. FA IPv4 Address Extension .................................53
   10. IANA Considerations ...........................................53
      10.1. New Extension Values .....................................53
      10.2. Generalized Link Layer and IP Address Identifier (LLA) ...54