http://www.rfc-editor.org/rfc/rfc6333.txt
RFC 6333: Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion, A. Durand, R. Droms, J. Woodyatt, Y. Lee2011-08-01T23:00:00-00:00This document revisits the dual-stack model and introduces the Dual- Stack Lite technology aimed at better aligning the costs and benefits of deploying IPv6 in service provider networks. Dual-Stack Lite enables a broadband service provider to share IPv4 addresses among customers by combining two well-known technologies: IP in IP (IPv4- in-IPv6) and Network Address Translation (NAT). [STANDARDS-TRACK]