This document specifies an Inter-Chassis Communication Protocol (ICCP) that enables Provider Edge (PE) device redundancy for Virtual Private Wire Service (VPWS) and Virtual Private LAN Service (VPLS) applications. The protocol runs within a set of two or more PEs@ forming a Redundancy Group@ for the purpose of synchronizing data among the systems. It accommodates multi-chassis attachment circuit redundancy mechanisms as well as pseudowire redundancy mechanisms.