IPv6 Doc Prefix: IPv6 Address Prefix Reserved for Documentation

Network Working Group                                          G. Huston
Request for Comments: 3849                                       Telstra
Category: Informational                                          A. Lord
                                                                   APNIC
                                                                P. Smith
                                                                   Cisco
                                                               July 2004


             IPv6 Address Prefix Reserved for Documentation

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   To reduce the likelihood of conflict and confusion when relating
   documented examples to deployed systems, an IPv6 unicast address
   prefix is reserved for use in examples in RFCs, books, documentation,
   and the like.  Since site-local and link-local unicast addresses have
   special meaning in IPv6, these addresses cannot be used in many
   example situations.  The document describes the use of the IPv6
   address prefix 2001:DB8::/32 as a reserved prefix for use in
   documentation.

1.  Introduction

   The address architecture for IPv6 [1] does not specifically allocate
   an IPv6 address prefix for use for documentation purposes.
   Documentation material is currently using address prefixes drawn from
   address blocks already allocated or assigned to existing
   organizations or to well known ISPs, or drawn from the currently
   unallocated address pool.  Such use conflicts with existing or future
   allocations or assignments of IPv6 address space.

   The problems such conflicts may cause have already been encountered
   with IPv4 where literal use of documented examples in a production
   environment causes address and routing conflicts with existing
   services.  In making an explicit allocation of a documentation
   address prefix, it is intended that such operational problems may be
   avoided for IPv6.

   Similar, but different, discussion also applies to top level domain
   names and some have been reserved for similar purposes [2].

2.  Documentation IPv6 Address Prefix

   To allow documentation to accurately describe deployment examples,
   the use of site local or link local addresses is inappropriate, and a
   unicast address block is required.  All IPv6 unicast address space is
   currently marked as reserved, unassigned or has been assigned to the
   Internet Assigned Numbers Authority (IANA) for further redistribution
   to the Regional Internet Registries (RIRs) [1], but no unicast
   address space has been specifically nominated for the purposes of use
   in documented examples.

   Following acceptance within the Asia Pacific regional addressing
   community of a proposal for a block of IPv6 address space to be
   reserved for documentation purposes, the Asia Pacific Network
   Information Centre (APNIC) allocated a unicast address prefix for
   documentation purposes.  The address block is within the range of a
   conventional allocation size, so that documentation can accurately
   match deployment scenarios.

   The documentation prefix described in this memo can also be used to
   generate multicast addresses for documentation, using the Unicast
   prefix-based proposal [3].  Representing other kinds of multicast
   addresses in documentation is outside the scope of this memo.

   The prefix allocated for documentation purposes is 2001:DB8::/32

3.  Operational Implications

   This assignment implies that IPv6 network operators should add this
   address prefix to the list of non-routeable IPv6 address space, and
   if packet filters are deployed, then this address prefix should be
   added to packet filters.

   This is not a local-use address prefix, and the filters may be used
   in both local and public contexts.

4.  IANA Considerations

   IANA is to record the allocation of the IPv6 global unicast address
   prefix  2001:DB8::/32 as a documentation-only prefix  in the IPv6
   address registry.  No end party is to be assigned this address.

5.  Security Considerations

   IPv6 addressing documents do not have any direct impact on Internet
   infrastructure security.

6.  Acknowledgements

   The authors acknowledge the work of Marc Blanchet, assisted by Alain
   Durand, Robert Elz, Bob Fink, and Dave Thaler, in authoring a
   previous proposal for a V6 documentation prefix.

7.  References

7.1.  Normative References

   [1]  Hinden, R. and S. Deering, "Internet Protocol Version 6 (IPv6)
        Addressing Architecture", RFC 3513, April 2003.

7.2.  Informative References

   [2]  Eastlake 3rd, D. and A. Panitz, "Reserved Top Level DNS Names",
        BCP 32, RFC 2606, June 1999.

   [3]  Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6 Multicast
        Addresses", RFC 3306, August 2002.

Authors' Addresses

   Geoff Huston
   Telstra

   EMail: gih@apnic.net


   Anne Lord
   Asia Pacific Network Information Centre

   EMail: anne@apnic.net


   Philip Smith
   Cisco Systems

   EMail: pfs@cisco.com

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