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.



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  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.







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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: [email protected]


  Anne Lord
  Asia Pacific Network Information Centre

  EMail: [email protected]


  Philip Smith
  Cisco Systems

  EMail: [email protected]







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Full Copyright Statement

  Copyright (C) The Internet Society (2004).  This document is subject
  to the rights, licenses and restrictions contained in BCP 78, and
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Acknowledgement

  Funding for the RFC Editor function is currently provided by the
  Internet Society.









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