Protocols and standards
RFC 1853, IP in IP Tunneling
RFC 2473, Generic Packet Tunneling in IPv6 Specification
RFC 2893, Transition Mechanisms for IPv6 Hosts and Routers
RFC 3056, Connection of IPv6 Domains via IPv4 Clouds
RFC 4214, Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
RFC 6333, Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion