Simulation of Centralized Computer Communications Systems

In this concise paper we described the simulation approach for a general centralized computer communication system with emphasis on efficiency and versatility. The simulation program consists of three modules representing different levels in a hierarchy. The lowest level models the polled multidrop line connecting remote terminals to the concentrator. The second level models the trunk lines and the concentrator which interfaces the multidrop lines of lower speed to one or more higher speed trunk lines connected to a central computer. The highest level models the central computer which communicates with remote terminals via the trunks. A hybrid simulation approach is used to ease program development and to shorten computer running time. When feasible, empirical distributions, analytical formulas, or analytical models are used to eliminate simulation steps and simplify simulation procedures. The techniques developed are illustrated by application to the NASDAQ system.