Enhancements of the Fasnet protocol for Gbit/s metropolitan area networks

As MANs are increasingly being conceived to provide a short term solution to the realization of a public integrated broadband service environment for which absolute equality in bandwidth allocation will be mandatory, access fairness will become an important criterion in the choice of an access protocol. Access fairness is inherent in cyclic protocols such as Fasnet. But the performance of Fasnet degrades rapidly as the network becomes larger and faster. This is so because the round trip duration (RTD) becomes too large in relation to the time it takes to transmit a packet of information, prompting what is commonly termed the RTD limitation. The paper describes two variants of Fasnet, viz., slot reuse Fasnet and multichannel Fasnet, that reduce the RTD limitation to enable Fasnet to perform efficiently in a large, high-speed MAN. The performance of these variants of Fasnet are studied by means of computer simulation for a range of parameter values to show that they are superior to Fasnet