A Cisco router running a version of IOS that includes 6to4 support can either become a 6to4 client, if it only has IPv4 connectivity or, if the router already has global IPv6 connectivity, become a 6to4 relay.

Client configuration

To configure a Cisco router as a 6to4 client is rather easy and can be done by setting up a tunnel as follows:

One also has to set up the following route:

ipv6 route 2002::/16 Tunnel64

Configuration as a 6to4 relay

If the tunnel and route is configured as described above on a router, which also has outside connectivity to the rest of the IPv6 Internet, this router automatically functions as a 6to4 relay and can thus provide outside connectivity to all hosts connected to it by 6to4.