A comparative performance analysis of distributed queue dual busaccess control methods

摘要

Simulation results comparing several distributed queue dual bus(DQDB) medium access control methods are described. To address accessfairness problems in the IEEE P802.6 proposed standard for DQDBmetropolitan area networks (MANs), a method known as bandwidth balancing(BWB) was accepted as part of the draft proposed standard version 10(D10). Another method, known as reservation request control (RRC), wasreported earlier which showed that it also reduces these access fairnessproblems. It is shown that, under a wide range of operating conditions,RRC provides lower access time than BWB, typically an order-of-magnitudefaster convergence to a fair operating point, and performance very closeto an ideal round-robin queuing discipline. However, the additional RRCcomplexity and substantial differences between it and the current IEEEP802.6 proposed standard indicate that RRC is not justified for the nearterm. It is concluded that, with only minor added complexity, BWBprovides the needed performance improvements for currently envisionedDQDB MANs