From Fedora Project Wiki
Introduction
This page details the process for setting up a tunnel for IPv6 using the transition mechanism detailed in [1] using the anycast address 192.88.99.1
Instructions
All commands listed are run as a user with sufficient privileges. To obtain root privileges, enter su - and supply the root user password.
ip tunnel add tun6to4 mode sit ttl 80 remote any local DIR_PUBLIC_IPv4 ip link set dev tun6to4 up ip -6 addr add 2002:XXYY:ZZUU::1/16 dev tun6to4 ip -6 route add default via ::192.88.99.1 dev tun6to4 metric 1
Note that XXYY:ZZUU is the hexadecimal notation for DIR_PUBLIC_IPv4 (the public IPv4 address) as follows: 60.172.21.22 -> XXYY:ZZUU = 3CAC:15DE
(based on information from ipv6tf.org[2])