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.

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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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