IP Version 6 Addressing Architecture
RFC 2373

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 06

Network Working Group                                        R. Hinden
Request for Comments: 2373                                       Nokia
Obsoletes: 1884                                             S. Deering
Category: Standards Track                                Cisco Systems
                                                             July 1998

                  IP Version 6 Addressing Architecture

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

   This specification defines the addressing architecture of the IP
   Version 6 protocol [IPV6].  The document includes the IPv6 addressing
   model, text representations of IPv6 addresses, definition of IPv6
   unicast addresses, anycast addresses, and multicast addresses, and an
   IPv6 node's required addresses.

Table of Contents

   1. Introduction.................................................2
   2. IPv6 Addressing..............................................2
      2.1 Addressing Model.........................................3
      2.2 Text Representation of Addresses.........................3
      2.3 Text Representation of Address Prefixes..................5
      2.4 Address Type Representation..............................6
      2.5 Unicast Addresses........................................7
        2.5.1 Interface Identifiers................................8
        2.5.2 The Unspecified Address..............................9
        2.5.3 The Loopback Address.................................9
        2.5.4 IPv6 Addresses with Embedded IPv4 Addresses.........10
        2.5.5 NSAP Addresses......................................10
        2.5.6 IPX Addresses.......................................10
        2.5.7 Aggregatable Global Unicast Addresses...............11
        2.5.8 Local-use IPv6 Unicast Addresses....................11
      2.6 Anycast Addresses.......................................12
        2.6.1 Required Anycast Address............................13
      2.7 Multicast Addresses.....................................14

Hinden & Deering            Standards Track                     [Page 1]
RFC 2373              IPv6 Addressing Architecture             July 1998

        2.7.1 Pre-Defined Multicast Addresses.....................15
        2.7.2 Assignment of New IPv6 Multicast Addresses..........17
      2.8 A Node's Required Addresses.............................17
   3. Security Considerations.....................................18
   APPENDIX A: Creating EUI-64 based Interface Identifiers........19
   APPENDIX B: ABNF Description of Text Representations...........22
   APPENDIX C: CHANGES FROM RFC-1884..............................23
   REFERENCES.....................................................24
   AUTHORS' ADDRESSES.............................................25
   FULL COPYRIGHT STATEMENT.......................................26

1.0 INTRODUCTION

   This specification defines the addressing architecture of the IP
   Version 6 protocol.  It includes a detailed description of the
   currently defined address formats for IPv6 [IPV6].

   The authors would like to acknowledge the contributions of Paul
   Francis, Scott Bradner, Jim Bound, Brian Carpenter, Matt Crawford,
   Deborah Estrin, Roger Fajman, Bob Fink, Peter Ford, Bob Gilligan,
   Dimitry Haskin, Tom Harsch, Christian Huitema, Tony Li, Greg
   Minshall, Thomas Narten, Erik Nordmark, Yakov Rekhter, Bill Simpson,
   and Sue Thomson.

   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 [RFC 2119].

2.0 IPv6 ADDRESSING

   IPv6 addresses are 128-bit identifiers for interfaces and sets of
   interfaces.  There are three types of addresses:

     Unicast:   An identifier for a single interface.  A packet sent to
                a unicast address is delivered to the interface
                identified by that address.

     Anycast:   An identifier for a set of interfaces (typically
                belonging to different nodes).  A packet sent to an
                anycast address is delivered to one of the interfaces
                identified by that address (the "nearest" one, according
                to the routing protocols' measure of distance).

     Multicast: An identifier for a set of interfaces (typically
                belonging to different nodes).  A packet sent to a
                multicast address is delivered to all interfaces
                identified by that address.

Hinden & Deering            Standards Track                     [Page 2]