Based on System-Level Modeling*

System-level design methods enable developing an executable model which allows the qualitative and quantitative properties to be analyzed before the system is actually realized. The modeling language Parallel Object-Oriented Specification Language (POOSL) has been proven to be very useful for system-level modeling when we want to describe concurrent and distributed behaviors effectively. The network protocols have many complex concurrent and distributed characteristics, thus it is very difficult to be analyzed by mathematical methods. One of the most promising solutions to this problem is system-level modeling and simulation. A number of parameters in the network protocol have a major effect on the overall performance. To be able to evaluate the effect, a system-level model of the network protocol is built in POOSL. Through the simulation of the model, results of the performance analysis on the influence of the parameters can be obtained. Furthermore, some key-parameters can be determined during the earliest phases of the design. This paper describes the experiences of using system-level modeling to analyze the performance properties of Sliding Window Protocol (SWP). The system-level model of SWP is built and the performance properties are investigated for a number of configurations of the system parameters. Key words