A fair and fast protocol for DQDB metropolitan area networks

Abstract

Distributed queue dual bus (DQDB) was shown to exhibit throughput unfairness problems in which bandwidth allocation is dependent on the physical locations of nodes, as the size and load of the network increase. To eliminate the unfairness problems, various mechanisms have been proposed. This paper first analyzes the unfairness problems and presents a survey of these mechanisms, including an analysis of their strengths and weaknesses. The paper then proposes a fair and fast protocol, called multiple segment control (MSC). MSC grants node multiple slots on continuation basis for any single request issued in an attempt to minimize the propagation delay. The node keeps being granted until it has issued an 'end' request. Consequently, MSC offers fair and high throughput to all nodes for both light and heavy load conditions. Finally, the performance of MSC is evaluated and compared with that of DQDB via simulation results.<>