Evaluation of packet delays and packet bundling in ATM backbones

Asynchronous transfer mode (ATM) is envisioned to be the high-speed backbone for existing LAN technologies. In this paper we examine the performance of ATM-based backbones connecting LANs supporting the military training exercises of distributed interactive simulation (DIS). The total end-to-end packet delay in the ATM backbone, the delay in the source interworking unit (IWU), the delay in the destination IWU, the segmentation byte overhead due to partial utilization of the last ATM cell, and the total ATM bit rate have been evaluated for two different distributions of packet sizes. Our tests show that as the mean packet length increases, the ATM end-to-end delay increases with a rate much higher than the rate of increase in the time needed to transmit the packet. Based on these results, the performance of packet bundling as a bandwidth reduction technique in ATM-based backbones is found to be not rewarding