Tunneling means encapsulating data of one protocol type within
another protocol and sending it over a channel that understands the
encapsulating protocol. This driver implements encapsulation of IPv6
- into IPv4 packets. This is useful if you want to connect to IPv6
+ into IPv4 packets. This is useful if you want to connect two IPv6
networks over an IPv4-only path.
Saying M here will produce a module called sit.ko. If unsure, say Y.