Simple priority scheme for multichannel CSMA/CD local area networks

The authors describe and analyse a new priority CSMA/CD protocol for multichannel local area networks. In this scheme, low priority messages can be transmitted by using the CSMA/CD protocol only when the number of idle channels exceeds a certain value. Following a general description of the proposed priority protocol, the authors analyse the protocol by first formulating the various state transition probabilities of the network. The delay and throughput characteristics of the various priority messages are then calculated and presented. It is found that the performance of this simple scheme is comparable to the priority schemes studies by G.L. Choudhury and S.S. Rappaport (see IEEE Trans. Commun. vol. COM-33, no.7, p.620-6 (1985)) for CSMA/CD networks. Also, in order not to starve off low priority stations, the largest number of idle channels when the transmission of low priority packets becomes inhibited should not be more than about one third of the total number of channels.<>