The structure design on IWU and VPN in FR/ATM interworking

Frame relay/asynchronous transfer mode (FR/ATM) interworking is foreseen to appear in the near future. The FR network is a frame based connection-oriented network, while the ATM network is a cell based connection-oriented network. In the heterogeneous network interworking environment, the connectionless data service is expected to be one of the most important services. In this paper, we review the ways to provide a connectionless data service in these networks and to design an FR/ATM interworking unit (IWU) and a feasible and flexible virtual private network (VPN). We briefly review the characteristics of the FR network, ATM network, and the interworking architecture by the standardization body, then we describe LAN interconnection via FR/ATM interworking. Next, an FR/ATM IWU architecture and design issues are addressed. We discuss the future VPN architecture and show a flexible VPN communication structure based on some concepts from the defined ATM LAN and ITU-T I.364.