Short for Intra-Site Automatic Tunnel Addressing Protocol, ISATAP is a method of transmitting IPv6 packets on an IPv4 network that is most recently defined in RFC 5214. ISATAP works by mapping an IPv4 address into the IPv6 address and requires an ISATAP gateway on the IPv6 Internet and the IPv4 intranet.
As of April 2008, ISATAP is implemented in the Linux operating system kernel, beginning with Linux-2.6.25. ISATAP and on other systems including Microsoft Windows (XP, Vista, 7, and 8), Cisco IOS, 6WIND 6WINDGate, and FreeBSD/KAME.
Microsoft does not recommend the use of ISATAP across entire production networks. Instead, you should deploy native IPv6 routing capability.