draft-ietf-v6ops-v4v6-xlat-prefix-02.txt   rfc8215.txt 
IPv6 Operations T. Anderson Internet Engineering Task Force (IETF) T. Anderson
Internet-Draft Redpill Linpro Request for Comments: 8215 Redpill Linpro
Intended status: Standards Track June 20, 2017 Category: Standards Track August 2017
Expires: December 22, 2017 ISSN: 2070-1721
Local-use IPv4/IPv6 Translation Prefix Local-Use IPv4/IPv6 Translation Prefix
draft-ietf-v6ops-v4v6-xlat-prefix-02
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. within domains that enable IPv4/IPv6 translation mechanisms.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on December 22, 2017. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8215.
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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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
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 coexistence 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.
2. Terminology 2. Terminology
This document makes use of the following terms: This document uses 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 algorithms.
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, such IPv4/IPv6 translation mechanisms have been defined by the IETF, such
as [RFC6146] and [RFC7915]. These mechanisms target various as those defined in [RFC6146] and [RFC7915]. These mechanisms target
different use cases. An operator might therefore wish to make use of various different use cases. An operator might therefore wish to
several of them simultaneously. 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 algorithms
in [RFC6052]. More recent IETF documents describe IPv4/IPv6 specified in [RFC6052]. More recent RFCs 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 cannot make use of the WKP in a legitimate
fashion. fashion.
Also, because the WKP is a /96, an operator preferring to use the 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 their IPv4/IPv6 over an NSP can do so for only one of their IPv4/IPv6 translation
translation mechanisms. All others must necessarily use an NSP. 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 coexistence 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] algorithms or adhere to its
usage restrictions. usage restrictions.
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 a multiple The second criterion is that the prefix length chosen is a multiple
of 16. This ensures the prefix ends on a colon boundary when of 16. This ensures the prefix ends on a colon boundary 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] algorithms 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,
however, was considered as too wasteful by the IPv6 Operations however, was considered as too wasteful by the IPv6 Operations
working 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 as being 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
It is desirable to minimise the amount of additional "pollution" in It is desirable to minimise the amount of additional "pollution" in
the unallocated IPv6 address space caused by the reservation made by the unallocated IPv6 address space caused by the reservation made by
this document. Ensuring the reserved prefix is adjacent to the this document. Ensuring the reserved prefix is adjacent to the
64:ff9b::/96 WKP already reserved by [RFC6052] accomplishes this. 64:ff9b::/96 WKP already reserved by [RFC6052] accomplishes this.
Given the previous decision to use a prefix length of /48, this Given the previous decision to use a prefix length of /48, this
leaves two options: 64:ff9a:ffff::/48 and 64:ff9b:1::/48. leaves two options: 64:ff9a:ffff::/48 and 64:ff9b:1::/48.
64:ff9a:ffff::/48 has the benefit that it is completely adjacent to 64:ff9a:ffff::/48 has the benefit that it is completely adjacent to
the [RFC6052] WKP. That is, 64:ff9a:ffff::/48 and 64:ff9b::/96 the [RFC6052] WKP. That is, 64:ff9a:ffff::/48 and 64:ff9b::/96
combines to form a uninterrupted range of IPv6 addresses starting combine to form an uninterrupted range of IPv6 addresses starting
with 64:ff9a:ffff:: and ending with 64:ff9b::ffff:ffff. with 64:ff9a: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::/48 is much larger than the smallest possible and 64:ff9a: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
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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 with any kind of IPv4/IPv6 translation mechanism deployed within
their 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 differently 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 more-specific prefix may only be used in inter- 64:ff9b:1::/48 or any more-specific prefix may only be used in inter-
domain routing if done in accordance with the rules described in domain routing if done in accordance with the rules described in
Section 3.2 of [RFC6052]. Section 3.2 of [RFC6052].
Note that 64:ff9b:1::/48 (or any more-specific prefix) is distinct Note that 64:ff9b:1::/48 (or any more-specific prefix) is distinct
from the WKP 64:ff9b::/96. Therefore, the restrictions on the use of from the WKP 64:ff9b::/96. Therefore, the restrictions on the use of
the WKP described in Section 3.1 of [RFC6052] do not apply to the use the WKP described in Section 3.1 of [RFC6052] do not apply to the use
of 64:ff9b:1::/48. 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 (see Section 4.2) that the IETF could
reserve in the future for entirely different purposes. potentially 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 Section 4.1 of [RFC6052] contains further discussion about IPv4/IPv6
translation and checksum neutrality. 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] algorithms for all of its address translations.
However, in order to attain checksum neutrality it is imperative that However, in order to attain checksum neutrality, it is imperative
the translation prefix is chosen carefully. Specifically, in order that the translation prefix be chosen carefully. Specifically, in
for a 96-bit [RFC6052] prefix to be checksum neutral, all the six order for a 96-bit [RFC6052] prefix to be checksum neutral, all the
16-bit words in the prefix must add up to a multiple of 0xffff. six 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
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
7. IANA Considerations 7. IANA Considerations
(Note to the RFC Editor: Please replace occurrences of "TBD" in this The IANA has added the following entry to the "IANA IPv6 Special-
section with the assigned RFC number of this document and delete this Purpose Address Registry":
note.)
The IANA is requested to add the following entry to the IPv6 Special-
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 | RFC 8215 |
| Allocation Date | (TBD) | | Allocation Date | 2017-06 |
| Termination Date | N/A | | Termination Date | N/A |
| Source | True | | Source | True |
| Destination | True | | Destination | True |
| Forwardable | True | | Forwardable | True |
| Global | False | | Globally Reachable | False |
| Reserved-by-Protocol | False | | Reserved-by-Protocol | False |
+----------------------+---------------------+ +----------------------+---------------------+
The IANA is furthermore requested to add the following footnote to The IANA has also added the following footnote to the 0000::/8 entry
the 0000::/8 entry of the Internet Protocol Version 6 Address Space of the "Internet Protocol Version 6 Address Space" registry:
registry:
64:ff9b:1::/48 reserved for Local-use IPv4/IPv6 Translation [TBD] 64:ff9b:1::/48 reserved for Local-Use IPv4/IPv6 Translation
[RFC8215].
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
[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>. <https://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>. <https://www.rfc-editor.org/info/rfc1918>.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6 NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <http://www.rfc-editor.org/info/rfc6146>. April 2011, <https://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>. <https://www.rfc-editor.org/info/rfc7915>.
Acknowledgements Acknowledgements
The author would like to thank Fred Baker, Mohamed Boucadair, Brian E The author would like to thank Fred Baker, Mohamed Boucadair,
Carpenter, Pier Carlo Chiodi, Joe Clarke, David Farmer, Suresh Brian E. Carpenter, Pier Carlo Chiodi, Joe Clarke, David Farmer,
Krishnan, Warren Kumari, Holger Metschulat, Federico Santandrea and Suresh Krishnan, Warren Kumari, Holger Metschulat, Federico
David Schinazi for contributing to the creation of this document. 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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