Transition Mechanisms for IPv6 Hosts and Routers
RFC 2893

 
Document Type RFC - Proposed Standard (August 2000; No errata)
Obsoleted by RFC 4213
Obsoletes RFC 1933
Last updated 2013-03-02
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IESG IESG state RFC 2893 (Proposed Standard)
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Network Working Group                                        R. Gilligan
Request for Comments: 2893                                FreeGate Corp.
Obsoletes: 1933                                              E. Nordmark
Category: Standards Track                         Sun Microsystems, Inc.
                                                             August 2000

            Transition Mechanisms for IPv6 Hosts and Routers

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 (2000).  All Rights Reserved.

Abstract

   This document specifies IPv4 compatibility mechanisms that can be
   implemented by IPv6 hosts and routers.  These mechanisms include
   providing complete implementations of both versions of the Internet
   Protocol (IPv4 and IPv6), and tunneling IPv6 packets over IPv4
   routing infrastructures.  They are designed to allow IPv6 nodes to
   maintain complete compatibility with IPv4, which should greatly
   simplify the deployment of IPv6 in the Internet, and facilitate the
   eventual transition of the entire Internet to IPv6.  This document
   obsoletes RFC 1933.

Gilligan & Nordmark         Standards Track                     [Page 1]
RFC 2893               IPv6 Transition Mechanisms            August 2000

Table of Contents

   1.  Introduction.............................................    2
      1.1.  Terminology.........................................    3
      1.2.  Structure of this Document..........................    5
   2.  Dual IP Layer Operation..................................    6
      2.1.  Address Configuration...............................    7
      2.2.  DNS.................................................    7
      2.3.  Advertising Addresses in the DNS....................    8
   3.  Common Tunneling Mechanisms..............................    9
      3.1.  Encapsulation.......................................   11
      3.2.  Tunnel MTU and Fragmentation........................   11
      3.3.  Hop Limit...........................................   13
      3.4.  Handling IPv4 ICMP errors...........................   13
      3.5.  IPv4 Header Construction............................   15
      3.6.  Decapsulation.......................................   16
      3.7.  Link-Local Addresses................................   17
      3.8.  Neighbor Discovery over Tunnels.....................   18
   4.  Configured Tunneling.....................................   18
      4.1.  Default Configured Tunnel...........................   19
      4.2.  Default Configured Tunnel using IPv4 "Anycast Address" 19
      4.3.  Ingress Filtering...................................   20
   5.  Automatic Tunneling......................................   20
      5.1.  IPv4-Compatible Address Format......................   20
      5.2.  IPv4-Compatible Address Configuration...............   21
      5.3.  Automatic Tunneling Operation.......................   22
      5.4.  Use With Default Configured Tunnels.................   22
      5.5.  Source Address Selection............................   23
      5.6.  Ingress Filtering...................................   23
   6.  Acknowledgments..........................................   24
   7.  Security Considerations..................................   24
   8.  Authors' Addresses.......................................   24
   9.  References...............................................   25
   10.  Changes from RFC 1933...................................   26
   11.  Full Copyright Statement................................   29

1.  Introduction

   The key to a successful IPv6 transition is compatibility with the
   large installed base of IPv4 hosts and routers.  Maintaining
   compatibility with IPv4 while deploying IPv6 will streamline the task
   of transitioning the Internet to IPv6.  This specification defines a
   set of mechanisms that IPv6 hosts and routers may implement in order
   to be compatible with IPv4 hosts and routers.

   The mechanisms in this document are designed to be employed by IPv6
   hosts and routers that need to interoperate with IPv4 hosts and
   utilize IPv4 routing infrastructures.  We expect that most nodes in

Gilligan & Nordmark         Standards Track                     [Page 2]
RFC 2893               IPv6 Transition Mechanisms            August 2000

   the Internet will need such compatibility for a long time to come,
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