6to4
B. Carpenter & K. Moore. Connection of IPv6 Domains via IPv4 Clouds. RFC 3056, February 2001.
R. Gilligan & E. Nordmark. Transition Mechanisms for IPv6 Hosts and Routers. RFC 2893, August 2000.
C. Huitema. An Anycast Prefix for 6to4 Relay Routers. RFC 3068, June 2001.
P. Savola & C. Patel. Security Considerations for 6to4. RFC 3964, December 2004.