IPv6 transition mechanism: Difference between revisions

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'''IPv6 transition mechanisms''' are usedimportant technologies to allowfacilitate the transitioning of the [[Internet]] from its initial [[IPv4]] infrastructure to the next generation addressing system of [[IPv6]]. Specifically, they are methods that allow IPv6-connected hosts to access [[IPv4]]-only Internet resources and hosts. Some IPv6 transition mechanisms were first defined in RFC 1933, but this RFCwhich has been obsoletedsuperseded by newer developments in RFC 4213.

The [[Internet Engineering Task Force]] (IETF) conducts working groups and discussions through the IETF Internet Drafts and [[Requests for Comments]] processes to development these methods.

There exists an ongoing process for a IPv4/IPv6 translation framework as described in [http://www.viagenie.ca/ietf/draft/draft-baker-behave-v4v6-framework-02.txt draft-baker-behave-v4v6-framework]. It also explains the background of the problem and some expected uses. Another document describes the translation proposal [http://www.viagenie.ca/ietf/draft/draft-baker-behave-v4v6-translation-02.txt draft-baker-behave-v4v6-translation]. There are two concrete protocol proposals that have much in common: [http://www.viagenie.ca/ietf/draft/draft-bagnulo-behave-nat64-03.txt NAT64]/[http://www.viagenie.ca/ietf/draft/draft-bagnulo-behave-dns64-02.txt DNS64] and [http://www.viagenie.ca/ietf/draft/draft-baker-behave-ivi-01.txt IVI]. Also [http://tools.ietf.org/html/draft-ietf-softwire-dual-stack-lite-02 Dual Stack Lite] has been proposed.

== Stateless IP/ICMP Translation (SIIT) ==

There are also some implementations for proposed solutions:

* [http://www.litech.org/ptrtd/ pTRTd] user-level NAT-PT

* [http://tomicki.net/naptd.php naptd] user-level NAT-PT

* [http://v6s.6test.edu.cn/ IVI] ([http://www.ivi2.org/ second page])

* [http://ecdysis.viagenie.ca/ NAT64]

A good text comparing all proposals is [http://www.viagenie.ca/ietf/draft/draft-wing-nat-pt-replacement-comparison-02.txt draft-wing-nat-pt-replacement-comparison].

== Stateless IP/ICMP Translation (SIIT) ==

RFC 2765 defines a mechanism known as ''Stateless IP/ICMP Translation'', or '''SIIT'''. SIIT is a mechanism which translates between [[IPv6]] packet headers and [[IPv4]] packet headers. It was initially drafted in February 2000 by E. Nordmark of [[Sun Microsystems]].

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Due to the method in which SIIT operates it is not a sufficient migration mechanism in that it is incapable of coordinating more than two unique addresses on either side. This means that every IPv6 host would be required to have a globally routable IPv4 address as well.

== NAT-PT ==

''Network Address Translation/Protocol Translation'' (or simply '''NAT-PT''') is defined in RFC 2766 but due to numerous problems, it has been obsoleted by RFC 4966 and deprecated to historic status. It is typically used in conjunction with a [[Domain Name System|DNS]] [[Application-level gateway]] (DNS-ALG) implementation.

== NAPT-PT ==

While almost identical to NAT-PT, ''Network Address Port Translation + Protocol Translation'' which is also described in RFC 2766 adds translation of the ports as well as the address. This is done primarily to avoid two hosts on one side of the mechanism from using the same exposed port on the other side of the mechanism, which could cause application instability and/or security flaws.

This mechanism has been deprecated by RFC 4966.

== Transport Relay Translation (TRT) ==

RFC 3142 defines the ''Transport Relay Translation'' (TRT) method. This is the most common form of NAT-PT/NAPT-PT but relies on DNS translation between AAAA and A records known as ''DNS-ALG'' as defined in RFC 2694.

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== See also ==

*[[Comparison of IPv6 application support]]

*[[stone (software)]]: port translator for Windows & Unix-based systems.

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*[[pTRTd]]: user space TRT implementation

== References ==

*ISBN 3-540-24524-3: ''IPv6 in Practice'' by, Benedikt Stockebrand, (2006), ISBN 3-540-24524-3

*RFC 2767, '''Bump-in-the-Stack / Bump-in-the-API'''

*RFC 3089, '''Socks-based Gateway'''

*RFC 3142, '''TCP-UDP Relay'''

*RFC 4966, '''Reasons to Move the Network Address Translator - Protocol Translator (NAT-PT) to Historic Status'''

== External links ==

*[http://www.join.uni-muenster.de/Dokumente/Howtos/Howto_TRT.php?lang=en TRT Howto from 2003]

*[http://student.grm.hia.no/master/ikt03/ikt6400/g03/filer/Hovedprosjekt_G3.doc IPv6 - Prospects and problems: a technical and management investigation into the deployment of IPv6]

A good text comparing all proposals is *[http://www.viagenie.ca/ietf/draft/draft-wing-nat-pt-replacement-comparison-02.txt draftA Comparison of Proposals to Replace NAT-wing-nat-pt-replacement-comparisonPT].

*[http://tools.ietf.org/html/draft-baker-behave-v4v6-translation-02 draft-baker-behave-v4v6-framework]

*[http://tools.ietf.org/html/draft-baker-behave-v4v6-translation-02 draft-baker-behave-v4v6-translation]

*[http://smakd.potaroo.net/ietf/all-ids/draft-bagnulo-behave-nat64-03.txt NAT64]

*[http://tools.ietf.org/html/draft-ietf-behave-dns64-02 DNS64]

*[http://tools.ietf.org/id/draft-baker-behave-ivi-01.txt IVI]

*[http://tools.ietf.org/html/draft-ietf-softwire-dual-stack-lite-02 Dual Stack Lite]

* [http://www.litech.org/ptrtd/ pTRTd] user-level NAT-PT

* [http://tomicki.net/naptd.php naptd] user-level NAT-PT

* [http://v6s.6test.edu.cn/ IVI] ([http://www.ivi2.org/ second page])

* [http://ecdysis.viagenie.ca/ NAT64]

[[Category:IPv6]]