Network Working Group M. Blanchet
Internet-Draft Viagenie
Expires: December 31, 2001 July 2, 2001
IPv6 Address Space Reserved for Documentation
draft-blanchet-ngtrans-exampleaddr-01
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Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract
To reduce the likelihood of conflict and confusion, an IPv6 prefix is
reserved for use in examples in RFCs, books, documentation, and the
like. Since site local addresses have special meaning in IPv6, these
cannot be used in many example situations and are confusing.
Instead, an IPv6 prefix 3ffe:ffff::/32 is reserved in the range of
the test address space.
1. Rationale
IPv6 introduces many types of addresses in its addressing
architecture [1], like scoped addresses (link-local, site-local) and
global addresses. It also introduces mechanisms for renumbering
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[2][5]. Since IPv6 has many new ways to use addresses, this means an
increase use of examples and scenarios for documenting the use of
addresses.
RFCs, vendor documentation, books and the like use examples with
addresses. Authors always have an issue of using: already allocated
addresses, not currently allocated addresses or private (site-local
in IPv6) addresses in their examples. Using the configuration
examples in a real environment can cause a problem. If the example
uses site-local as global address example, then the actual mechanism
for handling scoped addresses with site-local scoping can not be
done. If allocated addresses are used, then this obviously can make
address spoofing inadvertly if the environment is connected to the
internet. Same could happen for a non-currently allocated address
space that becomes allocated.
Similar, but different, discussion also applies to top level domain
names and some have been reserved for similar purposes [4].
2. Non Use
This reserved address space MUST NOT be used for private networks or
test networks. Use instead site-local [1].
3. Multicast
Multicast addresses can also be reserved for documentation using this
document reserved address space together with the Unicast prefix-
based proposal [6] for multicast addresses.
4. Assignment
The prefix 3ffe:ffff::/32, out of the test address space [3]
currently used on the 6bone, is reserved for the purpose of this
draft. The 6bone and the Internet MUST never use that prefix.
A /32 was chosen as a compromise. Multiple site prefixes and
multihoming could not be demonstrated with a prefix greater than /47.
A /24, which could be used for multiple TLA in exchange examples, was
seen as too much space consumed for documentation. The compromise
was /32. 3ffe:ffff::/32 was chosen as the last /32 in the current
reserved test space[3].
5. IANA Considerations
IANA reserves 3ffe:ffff::/32 address space out of the test address
space so that no one will ever receive this allocation, even if the
3ffe::/16 test address space is reallocated.
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6. Security Considerations
This document encourages the use of test addresses in documentation
so that less issues will arise from people that could instead use
address space already allocated or to be allocated in the future.
These could cause ip address spoofing. This proposal minimize such
possible conflicts.
7. Acknowledgements
In alphabetical order, Alain Durand, Robert Elz, Bob Fink and Dave
Thaler contributed to the discussion and improvements of this draft.
References
[1] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, July 1998.
[2] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
[3] Hinden, R., Fink, R. and J. Postel, "IPv6 Testing Address
Allocation", RFC 2471, December 1998.
[4] Eastlake, D. and A. Panitz, "Reserved Top Level DNS Names", BCP
32, RFC 2606, June 1999.
[5] Crawford, M., "Router Renumbering for IPv6", RFC 2894, August
2000.
[6] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6 Multicast
Addresses", Internet-draft, Work in progress draft-ietf-ipngwg-
uni-based-mcast-01.txt, January 2001.
Author's Address
Marc Blanchet
Viagenie
2875 boul. Laurier, bureau 300
Sainte-Foy, QC G1V 2M2
Canada
Phone: +1 418 656 9254
EMail: Marc.Blanchet@viagenie.qc.ca
URI: http://www.viagenie.qc.ca/
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