Performance degradation of the IEEE 802.4 token bus network in a noisy environment

This paper analyzes the performance degradation of the IEEE 802.4 token bus network in a noisy environment where clustered noises are generated with non-zero durations. The operation of the token passing mechanism in a token bus network is modeled by a state machine considering the effects of noise, and then the detailed token passing operation under clustered noise is investigated with the state machine model. The mean token passing time and the mean token rotation time are derived from the detailed token passing operation to evaluate the performance degradation of the IEEE 802.4 token bus network. The experiment on a test bed, which consists of an IEEE 802.4 token bus network and a noise generator, shows that the derived token rotation time is valid. The analysis shows that in a noisy environment the current recovery mechanism for the token passing operation becomes unreliable and the performance of the network decreases because the token is quite easily lost. (C) 1998 Elsevier Science B.V.