SMDS Measurements and Modeling to Predict Performance

This paper describes a performance study of a trial Switched Multimegabit Data Service (SMDS) link from the perspective of customers evaluating the feasibility of the link for some target applications. The goals were to take all measurements on the customer premises and to develop a methodology general enough to be used by customers to evaluate the link. We measured a lightly loaded system and developed a model of the SMDS connection suitable for evaluating applications via analysis or simulation. This paper documents our methodology, presents the SMDS connection delay values, and a likely breakdown of the constituents of that delay. We used this data to create a simulation model and to simulate a simple application. In the trial configuration, where geographical distances were small, SMDS network delay was one of the notable components of end-to-end delay in the SMDS connection. However, for most packets, throughput is limited by the T1 capacity for transmitting SMDS cells, not by the SMDS network capacity.