System Administration Guide: IP Services

Transitional Global Unicast Addresses

For transition purposes, the IPv6 protocol includes the ability to embed an IPv4 address within an IPv6 address. This type of IPv4 address facilitates the tunneling of IPv6 packets over existing IPv4 networks. One example of a transitional global unicast address is the 6to4 address. For more information on 6to4 addressing, refer to 6to4 Automatic Tunnels.