The Design and Implementation of an IPv6/IPv4 Network Address and Protocol Translator

IPv6 is a new version of the internetworking protocol designed to address the scalability and service shortcomings of the current standard, IPv4. Unfortunately, IPv4 and IPv6 are not directly compatible, so programs and systems designed to one standard can not communicate with those designed to the other. IPv4 systems, however, are ubiquitous and are not about to go away "over night" as the IPv6 systems are rolled in. Consequently, it is necessary to develop smooth transition mechanisms that enable applications to continue working while the network is being upgraded. In this paper we present the design and implementation of a transparent transition service that translates packet headers as they cross between IPv4 and IPv6 networks. While several such transition mechanisms have been proposed, ours is the first actual implementation. As a result, we are able to demonstrate and measure a working system, and report on the complexities involved in building and deploying such a system.