Dynamic behaviour of CSMA/CD network

Abstract

This paper studies the dynamic behaviour of a non-persistent CSMA/CD local area network when the loading changes between a high and low load state in a stochastic manner. The investigation starts with a description of the mathematical model used for characterizing the network and its operating environment. Based on this model, equations for the state transition probabilities and system equilibrium probabilites are formulated. Finally, by solving these equations, the throughput and delay performance of the system are numerically obtained and studied. It is found that when the average load period is longer than a few tens of packet lengths, the dynamic environment starts to degenerate into two non-interacting alternating static environments. On the other hand, when the average load period is shorter than a few packet lengths, the two loading environments start to merge to become a static one with an average constant load. These results serve to confirm that conventional investigations assuming constant loading are adequate for characterizing the behaviour of the network.