A Simulation Study of Packet Forwarding Methods for ATM Data Services

It is crucial for ATM to efficiently support existing data applications. One of the promising methods of supporting data over ATM uses connectionless servers providing a packet switching service in the ATM network. There are two primary methods for forwarding cell based datagrams in a connectionless server: reassembly mode, where the datagrams are reconstructed before forwarding, and streaming mode, where each cell is forwarded as it arrives. The two modes impact the packet loss probability at a connectionless server, the packet delay, the interleaving method used, the AAL used, and the buffer space required. This paper investigates the performance of two forwarding modes. Extensive simulations show that forwarding connectionless packets in streaming mode is shown to result in lower packet loss and end-to-end delay than reassembly mode. This research is supported in part by grants from the University of California MICRO program, Hughes Aircraft, Nippon Steel Information and Communication Systems Inc. (ENICOM), Hitachi Ltd., Hitachi America, Tokyo Electric Power Company, and Hewlett Packard (HP).