IPv6 Operations T. Anderson
Internet-Draft Redpill Linpro
Intended status: Standards Track June 21, 2016
Expires: December 23, 2016
64::/16: An IPv4/IPv6 translation prefix
draft-anderson-v6ops-v4v6-xlat-prefix-01
Abstract
This document reserves the IPv6 prefix 64::/16 for use with IPv4/IPv6
translation mechanisms.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 2
4. Choosing 64::/16 . . . . . . . . . . . . . . . . . . . . . . 3
5. Deployment Considerations . . . . . . . . . . . . . . . . . . 3
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 4
8. Normative References . . . . . . . . . . . . . . . . . . . . 4
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
[RFC6052] reserves the IPv6 prefix 64:ff9b::/96 for use with IPv4/
IPv6 translation mechanisms using the stateless IP address
translation algorithm specified in the same document.
This document extends this reservation to 64::/16. This facilitates
the co-existence of multiple IPv4/IPv6 translation mechanisms in the
same network without requiring the use of a Network-Specific Prefix.
2. Terminology
This document makes use of the following terms:
Network-Specific Prefix (NSP)
A globally unique prefix assigned by a network operator for use
with and IPv4/IPv6 translation mechanism, cf. [RFC6052]
Well-Known Prefix (WKP)
The prefix 64:ff9b::/96, which is reserved for use with the
[RFC6052] IPv4/IPv6 address translation algorithm.
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 [RFC2119].
3. Problem Statement
Since the WKP 64:ff9b::/96 was reserved by [RFC6052], several new
IPv4/IPv6 translation mechanisms have been defined by the IETF.
These target various different use cases. An operator might
therefore wish to make use of several of them simultaneously.
The smallest possible prefix supported by the [RFC6052] algorithm is
a /96. Because the WKP is a /96, an operator preferring to use a WKP
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over an NSP can only do so for only one of his IPv4/IPv6 translation
mechanisms. All others must necessarily use an NSP.
The WKP is reserved specifically for use with the algorithm specified
in [RFC6052]. More recent IETF documents describe IPv4/IPv6
translation mechanisms that use different algorithms. An operator
deploying such mechanisms can not use of the WKP in a legitimate
fashion.
Section 3.1 of [RFC6052] imposes certain restrictions on the use of
the WKP. These restrictions might conflict with the operator's
desired use of an IPv4/IPv6 translation mechanism.
In summary, there is a need for a prefix that facilitates the co-
existence of multiple IPv4/IPv6 translation mechanisms (that do not
necessarily use the [RFC6052] algorithm).
4. Choosing 64::/16
The prefix described in this document is intended as a generic
reservation that may be used for all present and future IPv4/IPv6
translation mechanisms, including the one described in [RFC6052].
Therefore, in order to prevent needless fragmentation of the IPv6
address space, it is prudent to choose a prefix that encompasses the
[RFC6052] WKP.
The [RFC6052] algorithm specifies possible prefix lengths as short as
/32. As previously discussed in Section 3, this document intends to
facilitate simultaneous operation of multiple IPv4/IPv6 translation
mechanisms in a single network. This means that the reservation must
necessarily have a prefix length shorter than /32. Furthermore, as
IPv6 addresses are divided into groups of 16 bits each, it is natural
to use a prefix length that aligns with a 16-bit boundary.
Taking all the above considerations account, the only possible prefix
value remaining is 64::/16.
5. Deployment Considerations
64::/16 is intended as a technology-agnostic and generic reservation.
A network operator may freely use it in combination with any IPv4/
IPv6 translation mechanism deployed within his network.
By default, IPv6 nodes and applications must not treat IPv6 addresses
within 64::/16 and outside 64:ff9b::/96 different from other globally
scoped IPv6 addresses. In particular, they must not make any
assumptions regarding the syntax or properties of those addresses
(e.g., the existence and location of embedded IPv4 addresses), or the
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type of associated translation mechanism (e.g., whether it is
stateful or stateless).
64:ff9b::/96 may only be used according to [RFC6052].
64::/16 or any other more-specific prefix may not be advertised in
inter-domain routing, except by explicit agreement between all
involved parties. Such prefixes MUST NOT be advertised to the
default-free zone.
6. IANA Considerations
The IANA is requested to reserve the IPv6 prefix 64::/16 for use with
IPv4/IPv6 translation.
7. Security Considerations
The reservation of 64::/16 is not known to cause any new security
considerations beyond those documented in Section 5 of [RFC6052].
8. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010,
<http://www.rfc-editor.org/info/rfc6052>.
Appendix A. Acknowledgements
The author would like to thank Holger Metschulat for contributing to
the creation of this document.
Author's Address
Tore Anderson
Redpill Linpro
Vitaminveien 1A
0485 Oslo
Norway
Phone: +47 959 31 212
Email: tore@redpill-linpro.com
URI: http://www.redpill-linpro.com
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