http://www.rfc-editor.org/rfc/rfc6888.txt
RFC 6888: Common Requirements for Carrier-Grade NATs (CGNs), S. Perreault, I. Yamagata, S. Miyakawa, A. Nakagawa, H. Ashida2013-04-01T23:00:00-00:00This document defines common requirements for Carrier-Grade NATs (CGNs). It updates RFC 4787.