4over6 Transit Solution Using IP Encapsulation and MP-BGP Extensions

The emerging and growing deployment of IPv6 networks will introduce cases where connectivity with IPv4 networks crossing IPv6 transit backbones is desired. This document describes a mechanism for automatic discovery and creation of IPv4-over-IPv6 tunnels via extensions to multiprotocol BGP. It is targeted at connecting islands of IPv4 networks across an IPv6-only backbone without the need for a manually configured overlay of tunnels. The mechanisms described in this document have been implemented, tested, and deployed on the large research IPv6 network in China