Chapter 6. IPv6 tunneling with Cisco and/or 6bone
By Marco Davids <marco@sara.nl>
NOTE to maintainer:
As far as I am concerned, this IPv6-IPv4 tunneling is not per definition GRE tunneling. You could tunnel IPv6 over IPv4 by means of GRE tunnel devices (GRE tunnels ANY to IPv4), but the device used here ("sit") only tunnels IPv6 over IPv4 and is therefore something different.