Why Translate between IPv4 and IPv6?
IPv4 and IPv6 networks are "incompatible". The IETF recommendation
has usually been to rely on dual-stack deployment: have both networks
coexist until IPv6 takes over IPv4. However, IPv6 growth has been much
slower than anticipated. Therefore, new IPv6-only deployments face an
interesting challenge, that of communicating with the predominantly
IPv4-only rest of the world. A similar problem is encountered when
legacy IPv4-only devices need to reach the IPv6 Internet.
The IETF is currently trying to solve these problems. One initial
proposal was NAT-PT [RFC2766].
However, it suffered from various issues which eventually caused it to
be declared obsolete in [RFC4966].
Recently, there has been a concerted effort coming from the BEHAVE,
V6OPS, and SOFTWIRE working groups to engineer a new solution.
Discussions at the 71st and 72nd IETF meetings (Philadelphia and
Dublin) led to the scheduling of a two-day interim meeting in Montréal
in October 2008. IPv4/IPv6 translation continued to be a major focus of
interest at the 73rd IETF meeting in Minneapolis, in November 2008.
This translation concerns has resulted in several draft documents.
The general framework for IPv4/IPv6 translation is described in [draft-ietf-behave-v6v4-framework].
It also explains the background of the problem, and some expected uses.
Another document describes the translation proposal [draft-ietf-behave-v6v4-xlate].
There are two concrete protocol proposals that have much in common:
and IVI [draft-xli-behave-ivi].
A good text comparing the proposals is [draft-wing-nat-pt-replacement-comparison]