IPv 4 / IPv 6 Translation

As the Internet makes the transition from IP version 4 to IP version 6, it will be necessary to allow IPv4-based clients to access IPv6-based servers, and IPv6-based clients to access legacy services. Network Address Translation–Protocol Translation (NATPT) can provide network protocol translation, and Application Layer Gateways (ALGs) can handle the cases where peer addresses are embedded in application-layer messages. We describe an implementation on a Linux router/translation server, the necessary configuration of the IPv4 and IPv6 environments, and the operation of ALGs for the File Transfer Protocol and for the Session Initiation Protocol. We will present a demonstration of basic communication (web client to web server), and of multimedia communication (based on the open-source VOCAL project). ∗On leave at Ericsson Research Canada, Open Systems Research Laboratory, Montréal, Québec, Canada