SIT
This section presents the following topics:
The Simple Internet Transition (SIT) protocol is a mechanism for tunneling an IPv6 packet over IPv4 routing infrastructures. A SIT packet employs a dual-IP layer of IPv4 and IPv6 in hosts and routers for direct interoperability with nodes that implement both protocols. The encapsulation includes two IPv6 addressing structures that embed IPv4 addresses within IPv6 addresses.
SIT includes an optional mechanism for translating headers of IPv4 packets into IPv6, and the headers of IPv6 packets into IPv4. This option allows nodes that implement only IPv6 to interoperate with nodes that implement only IPv4.