Performance analysis of complex communications systems

Whether a system is more complex than the one illustrated, or simpler, the Systems Network Analysis Program/Simulated Host Overview Technique makes it possible to evaluate many design alternatives with minimal effort. After the initial gathering of data, only three days were required to execute the design analysis discussed in this paper, including many variations not described. The time required for gathering data depends on whether automated data collection techniques are used. Many IBM software subsystems have associated monitoring facilities. If monitors are not available, data must be collected manually, or else a monitor must be written. Many installations already have methods of tracking system traffic and utilization and can use already available data. In making the design decisions, all the results were easily analyzed and correct conclusions readily drawn. With the simulation model it is possible to analyze design possibilities and learn how the system responds to changes without affecting the normal operation of an installation during the learning period. In addition, upon completion of several design alternatives, the user can develop a good understanding of why the system performs the way it does, and he can have confidence that it will perform up to expectations.