Keywords: unicast, site-local, link-local
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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RFC 3849 IPv6 Documentation Address July 2004
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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RFC 3849 IPv6 Documentation Address July 2004
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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RFC 3849 IPv6 Documentation Address July 2004
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