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Versions: 00 01 02 draft-ietf-v6ops-v4v6-xlat-prefix

IPv6 Operations                                              T. Anderson
Internet-Draft                                            Redpill Linpro
Updates: 6890 (if approved)                            September 9, 2016
Intended status: Standards Track
Expires: March 13, 2017


                 Local-use IPv4/IPv6 Translation Prefix
                draft-anderson-v6ops-v4v6-xlat-prefix-02

Abstract

   This document reserves the IPv6 prefix 64:ff9b:1::/48 for local use
   with IPv4/IPv6 translation mechanisms.  It updates RFC6890 in order
   to reflect this reservation.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 13, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   2
   4.  Choosing 64:ff9b:1::/48 . . . . . . . . . . . . . . . . . . .   3
   5.  Deployment Considerations . . . . . . . . . . . . . . . . . .   3
   6.  Checksum Neutrality . . . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   This document reserves 64:ff9b:1::/48 for local use with IPv4/IPv6
   translation mechanisms.  This facilitates the co-existence of
   multiple IPv4/IPv6 translation mechanisms in the same network without
   requiring the use of a Network-Specific Prefix assigned from the
   operator's allocated global unicast address space.

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.





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   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
   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 make 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:ff9b:1::/48

   The primary reason for choosing 64:ff9b:1::/48 is that it is adjacent
   to the [RFC6052] WKP 64:ff9b::/96.  As these two prefixes are
   intended for very similar uses, it is prudent to allow them to be
   referred to using a single aggregate (64:ff9b::/47).

   The prefix length of 48 bits was chosen in order to attain the goal
   of facilitating multiple simultaneous deployments of IPv4/IPv6
   translation in a single network.  The shortest IPv4/IPv6 translation
   prefixes reported to the V6OPS working group as being used in
   production was 64 bits. 64:ff9b:1::/48 will accommodate up to 65536
   such prefixes.

   While the [RFC6052] algorithm specifies IPv4/IPv6 translation
   prefixes as short as /32, facilitating for multiple instances of
   these was considered as too wasteful by the V6OPS working group.

5.  Deployment Considerations

   64:ff9b:1::/48 is intended as a technology-agnostic and generic
   reservation.  A network operator may freely use it in combination
   with any kind of IPv4/IPv6 translation mechanism deployed within his
   network.

   By default, IPv6 nodes and applications must not treat IPv6 addresses
   within 64:ff9b:1::/48 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



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   existence and location of embedded IPv4 addresses), or the type of
   associated translation mechanism (e.g., whether it is stateful or
   stateless).

   64:ff9b:1::/48 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.

   When 64:ff9b:1::/48 or a more-specific prefix is used with the
   [RFC6052] algorithm, it is considered to be a Network-Specific
   Prefix.

6.  Checksum Neutrality

   Use of 64:ff9b:1::/48 does not in itself guarantee checksum
   neutrality, as many of the IPv4/IPv6 translation algorithms it can be
   used with are fundamentally incompatible with checksum-neutral
   address translations.

   The Stateless IP/ICMP Translation algorithm [RFC7915] is one well-
   known algorithm that can operate in a checksum-neutral manner, when
   using the [RFC6052] algorithm for all of its address translations.
   However, in order to attain checksum neutrality is imperative that
   the translation prefix is chosen carefully.  Specifically, in order
   for a 96-bit [RFC6052] prefix to be checksum neutral, all the six
   16-bit words in the prefix must add up to a multiple of 0xffff.

   The following non-exhaustive list contains examples of translation
   prefixes that are checksum neutral when used with the [RFC7915] and
   [RFC6052] algorithms:

   o  64:ff9b:1:fffe::/96

   o  64:ff9b:1:fffd:1::/96

   o  64:ff9b:1:fffc:2::/96

   o  64:ff9b:1:abcd:0:5431::/96

   Section 4.1 of [RFC6052] contains further discussion about IPv4/IPv6
   translation and checksum neutrality.

7.  IANA Considerations

   The IANA is requested to add the following entry to the IPv6 Special-
   Purpose Address Registry:




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              +----------------------+---------------------+
              | Attribute            | Value               |
              +----------------------+---------------------+
              | Address Block        | 64:ff9b:1::/48      |
              | Name                 | IPv4-IPv6 Translat. |
              | RFC                  | (TBD)               |
              | Allocation Date      | (TBD)               |
              | Termination Date     | N/A                 |
              | Source               | True                |
              | Destination          | True                |
              | Forwardable          | True                |
              | Global               | False               |
              | Reserved-by-Protocol | False               |
              +----------------------+---------------------+

   The IANA is furthermore requested to add the following footnote to
   the 0000::/8 entry of the Internet Protocol Version 6 Address Space
   registry:

      64:ff9b:1::/48 reserved for Local-use IPv4/IPv6 Translation [TBD]

8.  Security Considerations

   The reservation of 64:ff9b:1::/48 is not known to cause any new
   security considerations beyond those documented in Section 5 of
   [RFC6052].

9.  References

9.1.  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>.

9.2.  Informative References

   [RFC7915]  Bao, C., Li, X., Baker, F., Anderson, T., and F. Gont,
              "IP/ICMP Translation Algorithm", RFC 7915,
              DOI 10.17487/RFC7915, June 2016,
              <http://www.rfc-editor.org/info/rfc7915>.




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Appendix A.  Acknowledgements

   The author would like to thank Fred Baker, David Farmer, Holger
   Metschulat and Pier Carlo Chiodi 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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