draft-ietf-v6ops-v4v6-xlat-prefix-00.txt   draft-ietf-v6ops-v4v6-xlat-prefix-01.txt 
IPv6 Operations T. Anderson IPv6 Operations T. Anderson
Internet-Draft Redpill Linpro Internet-Draft Redpill Linpro
Updates: 6890 (if approved) March 9, 2017 Intended status: Standards Track May 12, 2017
Intended status: Standards Track Expires: November 13, 2017
Expires: September 10, 2017
Local-use IPv4/IPv6 Translation Prefix Local-use IPv4/IPv6 Translation Prefix
draft-ietf-v6ops-v4v6-xlat-prefix-00 draft-ietf-v6ops-v4v6-xlat-prefix-01
Abstract Abstract
This document reserves the IPv6 prefix 64:ff9b:1::/48 for local use This document reserves the IPv6 prefix 64:ff9b:1::/48 for local use
within domains that enable IPv4/IPv6 translation mechanisms. This within domains that enable IPv4/IPv6 translation mechanisms.
document updates RFC6890.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 10, 2017. This Internet-Draft will expire on November 13, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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4. Why 64:ff9b:1::/48? . . . . . . . . . . . . . . . . . . . . . 3 4. Why 64:ff9b:1::/48? . . . . . . . . . . . . . . . . . . . . . 3
4.1. Prefix Length . . . . . . . . . . . . . . . . . . . . . . 3 4.1. Prefix Length . . . . . . . . . . . . . . . . . . . . . . 3
4.2. Prefix Value . . . . . . . . . . . . . . . . . . . . . . 4 4.2. Prefix Value . . . . . . . . . . . . . . . . . . . . . . 4
5. Deployment Considerations . . . . . . . . . . . . . . . . . . 4 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 4
6. Checksum Neutrality . . . . . . . . . . . . . . . . . . . . . 5 6. Checksum Neutrality . . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6 9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 7 9.2. Informative References . . . . . . . . . . . . . . . . . 7
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
This document reserves 64:ff9b:1::/48 for local use within domains This document reserves 64:ff9b:1::/48 for local use within domains
that enable IPv4/IPv6 translation mechanisms. This facilitates the that enable IPv4/IPv6 translation mechanisms. This facilitates the
co-existence of multiple IPv4/IPv6 translation mechanisms in the same co-existence of multiple IPv4/IPv6 translation mechanisms in the same
network without requiring the use of a Network-Specific Prefix network without requiring the use of a Network-Specific Prefix
assigned from the operator's allocated global unicast address space. assigned from the operator's allocated global unicast address space.
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This document makes use of the following terms: This document makes use of the following terms:
Network-Specific Prefix (NSP) Network-Specific Prefix (NSP)
A globally unique prefix assigned by a network operator for use A globally unique prefix assigned by a network operator for use
with an IPv4/IPv6 translation mechanism [RFC6052]. with an IPv4/IPv6 translation mechanism [RFC6052].
Well-Known Prefix (WKP) Well-Known Prefix (WKP)
The prefix 64:ff9b::/96, which is reserved for use with the The prefix 64:ff9b::/96, which is reserved for use with the
[RFC6052] IPv4/IPv6 address translation algorithm. [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 3. Problem Statement
Since the WKP 64:ff9b::/96 was reserved by [RFC6052], several new Since the WKP 64:ff9b::/96 was reserved by [RFC6052], several new
IPv4/IPv6 translation mechanisms have been defined by the IETF. IPv4/IPv6 translation mechanisms have been defined by the IETF, such
These mechanisms target various different use cases. An operator as [RFC6146] and [RFC7915]. These mechanisms target various
might therefore wish to make use of several of them simultaneously. different use cases. An operator might therefore wish to make use of
several of them simultaneously.
The WKP is reserved specifically for use with the algorithm specified The WKP is reserved specifically for use with the algorithm specified
in [RFC6052]. More recent IETF documents describe IPv4/IPv6 in [RFC6052]. More recent IETF documents describe IPv4/IPv6
translation mechanisms that use different algorithms. An operator translation mechanisms that use different algorithms. An operator
deploying such mechanisms can not make use of the WKP in a legitimate deploying such mechanisms can not make use of the WKP in a legitimate
fashion. fashion.
Also, because the WKP is a /96, an operator preferring to use a WKP Also, because the WKP is a /96, an operator preferring to use the WKP
over an NSP can only do so for only one of his IPv4/IPv6 translation over an NSP can only do so for only one of their IPv4/IPv6
mechanisms. All others must necessarily use an NSP. translation mechanisms. All others must necessarily use an NSP.
Section 3.1 of [RFC6052] imposes certain restrictions on the use of Section 3.1 of [RFC6052] imposes certain restrictions on the use of
the WKP, such as forbidding its use in combination with private IPv4 the WKP, such as forbidding its use in combination with private IPv4
addresses [RFC1918]. These restrictions might conflict with the addresses [RFC1918]. These restrictions might conflict with the
operator's desired use of an IPv4/IPv6 translation mechanism. operator's desired use of an IPv4/IPv6 translation mechanism.
In summary, there is a need for a local-use prefix that facilitates In summary, there is a need for a local-use prefix that facilitates
the co-existence of multiple IPv4/IPv6 translation mechanisms in a the co-existence of multiple IPv4/IPv6 translation mechanisms in a
single network domain, as well as the deployment of translation single network domain, as well as the deployment of translation
mechanisms that do not use the [RFC6052] algorithm or adhere to its mechanisms that do not use the [RFC6052] algorithm or adhere to its
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4. Why 64:ff9b:1::/48? 4. Why 64:ff9b:1::/48?
4.1. Prefix Length 4.1. Prefix Length
One of the primary goals of this document is to facilitate multiple One of the primary goals of this document is to facilitate multiple
simultaneous deployments of IPv4/IPv6 translation mechanisms in a simultaneous deployments of IPv4/IPv6 translation mechanisms in a
single network. The first criterion is therefore that the prefix single network. The first criterion is therefore that the prefix
length chosen must be shorter than the prefix length used by any length chosen must be shorter than the prefix length used by any
individual translation mechanism. individual translation mechanism.
The second criterion is that the prefix length chosen is is a The second criterion is that the prefix length chosen is a multiple
multiple of 16. This ensures the prefix ends on a colon boundary of 16. This ensures the prefix ends on a colon boundary when
when representing it in text, easing operator interaction with it. representing it in text, easing operator interaction with it.
The [RFC6052] algorithm specifies IPv4/IPv6 translation prefixes as The [RFC6052] algorithm specifies IPv4/IPv6 translation prefixes as
short as /32. In order to facilitate multiple instances of short as /32. In order to facilitate multiple instances of
translation mechanisms using /32s, while at the same time aligning on translation mechanisms using /32s, while at the same time aligning on
a 16-bit boundary, it would be necessary to reserve a /16. Doing so a 16-bit boundary, it would be necessary to reserve a /16. Doing so,
was however considered as too wasteful by the IPv6 Operations working however, was considered as too wasteful by the IPv6 Operations
group. working group.
The shortest translation prefix that was reported to the IPv6 The shortest translation prefix that was reported to the IPv6
Operations working group to be deployed in a live network was /64. Operations working group to be deployed in a live network was /64.
The longest 16-bit-aligned prefix length that can accommodate The longest 16-bit-aligned prefix length that can accommodate
multiple instances of /64 is /48. The prefix length of /48 was multiple instances of /64 is /48. The prefix length of /48 was
therefore chosen, as it satisfies both the criteria above, while at therefore chosen, as it satisfies both the criteria above, while at
the same time avoids wasting too much of the IPv6 address space. the same time avoids wasting too much of the IPv6 address space.
4.2. Prefix Value 4.2. Prefix Value
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starting with 64:ff9a:ffff:ffff:: and ending with 64:ff9b::ffff:ffff. starting with 64:ff9a:ffff:ffff:: and ending with 64:ff9b::ffff:ffff.
64:ff9b:1::/48 is, on the other hand, not completely adjacent to 64:ff9b:1::/48 is, on the other hand, not completely adjacent to
64:ff9b::/96. The range starting with 64:ff9b::1:0:0 and ending with 64:ff9b::/96. The range starting with 64:ff9b::1:0:0 and ending with
64:ff9b:0:ffff:ffff:ffff:ffff:ffff would remain unallocated. 64:ff9b:0:ffff:ffff:ffff:ffff:ffff would remain unallocated.
This particular drawback is, however, balanced by the fact that the This particular drawback is, however, balanced by the fact that the
smallest possible aggregate prefix that covers both the [RFC6052] WKP smallest possible aggregate prefix that covers both the [RFC6052] WKP
and 64:ff9a:ffff:ffff::/48 is much larger than the smallest possible and 64:ff9a:ffff:ffff::/48 is much larger than the smallest possible
aggregate prefix that covers both the [RFC6052] WKP and aggregate prefix that covers both the [RFC6052] WKP and
64:ff9b:1::/96. These aggregate prefixes are 64:ff9a::/31 and 64:ff9b:1::/48. These aggregate prefixes are 64:ff9a::/31 and
64:ff9b::/47, respectively. IPv6 address space is allocated using 64:ff9b::/47, respectively. IPv6 address space is allocated using
prefixes rather than address ranges, so it could be argued that prefixes rather than address ranges, so it could be argued that
64:ff9b:1::/96 is the option that would cause special-use prefixes 64:ff9b:1::/48 is the option that would cause special-use prefixes
reserved for IPv4/IPv6 translation to "pollute" the minimum possible reserved for IPv4/IPv6 translation to "pollute" the minimum possible
amount of unallocated IPv6 address space. amount of unallocated IPv6 address space.
Finally, 64:ff9b:1::/48 also has the advantage that its textual Finally, 64:ff9b:1::/48 also has the advantage that its textual
representation is considerably shorter than 64:ff9a:ffff:ffff::/48. representation is considerably shorter than 64:ff9a:ffff:ffff::/48.
While this might seem insignificant, the preference human network While this might seem insignificant, the preference human network
operators have for addresses that are simple to type should not be operators have for addresses that are simple to type should not be
underestimated. underestimated.
After weighing the above pros and cons, 64:ff9b:1::/48 was chosen. After weighing the above pros and cons, 64:ff9b:1::/48 was chosen.
5. Deployment Considerations 5. Deployment Considerations
64:ff9b:1::/48 is intended as a technology-agnostic and generic 64:ff9b:1::/48 is intended as a technology-agnostic and generic
reservation. A network operator may freely use it in combination reservation. A network operator may freely use it in combination
with any kind of IPv4/IPv6 translation mechanism deployed within his with any kind of IPv4/IPv6 translation mechanism deployed within
network. their network.
By default, IPv6 nodes and applications must not treat IPv6 addresses By default, IPv6 nodes and applications must not treat IPv6 addresses
within 64:ff9b:1::/48 different from other globally scoped IPv6 within 64:ff9b:1::/48 different from other globally scoped IPv6
addresses. In particular, they must not make any assumptions addresses. In particular, they must not make any assumptions
regarding the syntax or properties of those addresses (e.g., the regarding the syntax or properties of those addresses (e.g., the
existence and location of embedded IPv4 addresses), or the type of existence and location of embedded IPv4 addresses), or the type of
associated translation mechanism (e.g., whether it is stateful or associated translation mechanism (e.g., whether it is stateful or
stateless). stateless).
64:ff9b:1::/48 or any other more-specific prefix SHOULD NOT be 64:ff9b:1::/48 or any more-specific prefix may only be used in inter-
advertised in inter-domain routing, except by explicit agreement domain routing if done in accordance with the rules described in
between all involved parties. Such prefixes MUST NOT be advertised Section 3.2 of [RFC6052].
to the default-free zone.
When 64:ff9b:1::/48 or a more-specific prefix is used with the Note that 64:ff9b:1::/48 (or any more-specific prefix) is distinct
[RFC6052] algorithm, it is considered to be a Network-Specific from the WKP 64:ff9b::/96. Therefore, the restrictions on the use of
Prefix. the WKP described in Section 3.1 of [RFC6052] do not apply to the use
of 64:ff9b:1::/48.
Operators tempted to use the covering aggregate prefix 64:ff9b::/47 Operators tempted to use the covering aggregate prefix 64:ff9b::/47
to refer to all special-use prefixes currently reserved for IPv4/IPv6 to refer to all special-use prefixes currently reserved for IPv4/IPv6
translation should be warned that this aggregate includes a range of translation should be warned that this aggregate includes a range of
unallocated addresses (Section 4.2) that the IETF could potentially unallocated addresses (Section 4.2) that the IETF could potentially
reserve in the future for entirely different purposes. reserve in the future for entirely different purposes.
6. Checksum Neutrality 6. Checksum Neutrality
Use of 64:ff9b:1::/48 does not in itself guarantee checksum Use of 64:ff9b:1::/48 does not in itself guarantee checksum
neutrality, as many of the IPv4/IPv6 translation algorithms it can be neutrality, as many of the IPv4/IPv6 translation algorithms it can be
used with are fundamentally incompatible with checksum-neutral used with are fundamentally incompatible with checksum-neutral
address translations. address translations.
Section 4.1 of [RFC6052] contains further discussion about IPv4/IPv6
translation and checksum neutrality.
The Stateless IP/ICMP Translation algorithm [RFC7915] is one well- The Stateless IP/ICMP Translation algorithm [RFC7915] is one well-
known algorithm that can operate in a checksum-neutral manner, when known algorithm that can operate in a checksum-neutral manner, when
using the [RFC6052] algorithm for all of its address translations. using the [RFC6052] algorithm for all of its address translations.
However, in order to attain checksum neutrality is imperative that However, in order to attain checksum neutrality it is imperative that
the translation prefix is chosen carefully. Specifically, in order the translation prefix is chosen carefully. Specifically, in order
for a 96-bit [RFC6052] prefix to be checksum neutral, all the six 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. 16-bit words in the prefix must add up to a multiple of 0xffff.
The following non-exhaustive list contains examples of translation The following non-exhaustive list contains examples of translation
prefixes that are checksum neutral when used with the [RFC7915] and prefixes that are checksum neutral when used with the [RFC7915] and
[RFC6052] algorithms: [RFC6052] algorithms:
o 64:ff9b:1:fffe::/96 o 64:ff9b:1:fffe::/96
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The following non-exhaustive list contains examples of translation The following non-exhaustive list contains examples of translation
prefixes that are checksum neutral when used with the [RFC7915] and prefixes that are checksum neutral when used with the [RFC7915] and
[RFC6052] algorithms: [RFC6052] algorithms:
o 64:ff9b:1:fffe::/96 o 64:ff9b:1:fffe::/96
o 64:ff9b:1:fffd:1::/96 o 64:ff9b:1:fffd:1::/96
o 64:ff9b:1:fffc:2::/96 o 64:ff9b:1:fffc:2::/96
o 64:ff9b:1:abcd:0:5431::/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 7. IANA Considerations
(Note to the RFC Editor: Please replace occurrences of "TBD" in this
section with the assigned RFC number of this document and delete this
note.)
The IANA is requested to add the following entry to the IPv6 Special- The IANA is requested to add the following entry to the IPv6 Special-
Purpose Address Registry: Purpose Address Registry:
+----------------------+---------------------+ +----------------------+---------------------+
| Attribute | Value | | Attribute | Value |
+----------------------+---------------------+ +----------------------+---------------------+
| Address Block | 64:ff9b:1::/48 | | Address Block | 64:ff9b:1::/48 |
| Name | IPv4-IPv6 Translat. | | Name | IPv4-IPv6 Translat. |
| RFC | (TBD) | | RFC | (TBD) |
| Allocation Date | (TBD) | | Allocation Date | (TBD) |
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8. Security Considerations 8. Security Considerations
The reservation of 64:ff9b:1::/48 is not known to cause any new The reservation of 64:ff9b:1::/48 is not known to cause any new
security considerations beyond those documented in Section 5 of security considerations beyond those documented in Section 5 of
[RFC6052]. [RFC6052].
9. References 9. References
9.1. Normative 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. [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
DOI 10.17487/RFC6052, October 2010, DOI 10.17487/RFC6052, October 2010,
<http://www.rfc-editor.org/info/rfc6052>. <http://www.rfc-editor.org/info/rfc6052>.
9.2. Informative References 9.2. Informative References
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
and E. Lear, "Address Allocation for Private Internets", and E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,
<http://www.rfc-editor.org/info/rfc1918>. <http://www.rfc-editor.org/info/rfc1918>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <http://www.rfc-editor.org/info/rfc6146>.
[RFC7915] Bao, C., Li, X., Baker, F., Anderson, T., and F. Gont, [RFC7915] Bao, C., Li, X., Baker, F., Anderson, T., and F. Gont,
"IP/ICMP Translation Algorithm", RFC 7915, "IP/ICMP Translation Algorithm", RFC 7915,
DOI 10.17487/RFC7915, June 2016, DOI 10.17487/RFC7915, June 2016,
<http://www.rfc-editor.org/info/rfc7915>. <http://www.rfc-editor.org/info/rfc7915>.
Appendix A. Acknowledgements Acknowledgements
The author would like to thank Fred Baker, Mohamed Boucadair, Brian E The author would like to thank Fred Baker, Mohamed Boucadair, Brian E
Carpenter, Pier Carlo Chiodi, David Farmer, Holger Metschulat and Carpenter, Pier Carlo Chiodi, Joe Clarke, David Farmer, Warren
David Schinazi for contributing to the creation of this document. Kumari, Holger Metschulat, Federico Santandrea and David Schinazi for
contributing to the creation of this document.
Author's Address Author's Address
Tore Anderson Tore Anderson
Redpill Linpro Redpill Linpro
Vitaminveien 1A Vitaminveien 1A
0485 Oslo 0485 Oslo
Norway Norway
Phone: +47 959 31 212 Phone: +47 959 31 212
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