http://www.rfc-editor.org/rfc/rfc6877.txt
RFC 6877: 464XLAT: Combination of Stateful and Stateless Translation, M. Mawatari, M. Kawashima, C. Byrne2013-04-01T23:00:00-00:00This document describes an architecture (464XLAT) for providing limited IPv4 connectivity across an IPv6-only network by combining existing and well-known stateful protocol translation (as described in RFC 6146) in the core and stateless protocol translation (as described in RFC 6145) at the edge. 464XLAT is a simple and scalable technique to quickly deploy limited IPv4 access service to IPv6-only edge networks without encapsulation.