Performance study of national SMDS networks

A large-scale switched multimegabit data service (SMDS) trial conducted by Pacific Bell in 1991 is reported. The trial network consisted of four homogeneous SMDS switches and 21 end-user SMDS DS1 access links at more than 25 different sites. The topologies include the intra-LATA, intra-California, and East-to-West networks. The delay and throughput of these networks are analyzed on the basis of DS1 access speed. The performance was measured for a lightly loaded network traffic environment. The results show that the network delay increases linearly with the packet size and end-to-end distance. The throughput test is based on the file transfer protocol (FTP). The measurement results correlate well with the SMDS interface protocol (SIP) limitation. The sliding window, packet size, and acknowledgement process of the transmission control protocol/internet protocol (TCP/IP) also limit the SMDS throughput