Internet DRAFT - draft-anderson-v6ops-v4v6-xlat-prefix
draft-anderson-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
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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.
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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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