ABSTRACT
Analytic models are mathematical representations of the system through which the system input and output variables are related. Simulation models are usually computer programs to relate input and output variables of the system. Using simulation, a network may be modeled to any desired level of detail if the necessary system relationships are known. Simulation models can give more accurate results than analytical models because most of the assumptions made in the analytic models can be relaxed. The token-passing ring, developed at the Zurich Research Laboratories of IBM in 1972 and standardized as an access method in the IEEE Standard 802.5, is the best-known of all the ring systems. The token bus protocol was inspired by the token ring and standardized in the IEEE Standard 802.4. The basic operation of the token bus LAN is fully discussed by J. L. Hammond and P. J. P. O'Reilly and F. J. Kauffels, and its delay analysis is presented by Sachs and colleagues.
