Hierarchical performance modeling of computer communication systems

Performance analysis has a relevant role in network-architecture design, protocol selection and network tuning by providing estimates of network behavior in terms of throughput, response time and network utilization. This chapter focuses on the use of modeling methods and techniques in computer-networks performance evaluation. It discusses communication-system models defined by using the queueing formalism. The chapter presents the Hierarchical Modeling (HM) approach both in the definition of a system's model and in the model solution phase. It describes the use of hierarchical modeling and hybrid simulation in a general setting, and provides their use in computer-network analysis in a case study. HM can be used to define a system model through a top-down stepwise refinement technique. The system is represented by a succession of models, each defined at a different level of detail. The chapter aims to apply the hierarchical methodology to analyze the distributed system models obtained in the decomposition phase.