On the Wire The Transition to IPv6, Part I 4over6 for the China Education

T o promote the transition from IPv4 and topropel IPv6 development, some countries areestablishing large-scale pure IPv6 backbone networks. Yet, the large number of IPv4-based Internet applications and services presents the important challenge of how to let IPv4 networks communicate over IPv6 backbones. To address this problem, we propose an IPv4 network-interconnection mechanism for use in IPv6 networks. Our 4over6 solution defines a Border-Gateway Protocol (BGP)-based control plane to advertise 4over6 tunnels and IPv4 net-work prefixes. The data plane uses standard IP encapsulation and decapsulation performed at IPv4–IPv6 dual-stack routers. We realize IPv4 net-work interconnection by use of routing transport on the control plane and packet transport on the data plane. Because it avoids explicit tunnels and manual configuration, the 4over6 mechanism is lightweight, adaptive to dynamic routes, and transparent for network end systems. Highly scal-able and easy to deploy, it’s designed for inter-connecting large-scale networks. We’ve deployed a prototype implementation of the 4over6 mechanism on a native IPv6 backbone in China, based on current packet-encapsulatio