Technical Summary
This document describes a method for detecting the presence of DNS64
and for learning the IPv6 prefix used for protocol translation on an
access network. The method depends on the existence of a well-known
IPv4-only domain name "ipv4only.arpa". The information learned
enables nodes to perform local IPv6 address synthesis and to
potentially avoid NAT64 on dual-stack and multi-interface
deployments.
Working Group Summary
The document specifies a heuristic that is not perfect and so some
points were rough, but the constraint for this document was to operate
without changes to code (only configuration) in existing networks.
Given that constraint, there was strong consensus. Relaxing the
constraint would allow one to do better, and that is the focus of a
draft recently submitted to the PCP WG.
Document Quality
Jouni Korhonen did a prototype implementation that was presented in the
WG but not included in commercial product. Additionally, Cameron Byrne
(T-Mobile USA) has a 464XLAT implementation that also implements this
draft, as noted at
https://sites.google.com/site/tmoipv6/464xlat#TOC-Android-CLAT-on-a-UMTS-IPv6-only-network-with-DNS64-NAT64
Personnel
Document Shepherd: Dave Thaler (dthaler@microsoft.com)
Responsible Area Director: Martin Stiemerling