Effect of bandwidth balancing mechanism on fairness and performance of DQDB MANs

A potential problem with distributed queue dual bus (DQDB) is the achievement of fair sharing of bandwidth in terms of the location of the access node for queued arbitrated access. To compensate for this unfairness, the IEEE 802.6 standard recommends utilizing a bandwidth balancing (BWB) mechanism with the proper value of the system parameter named BWB-MOD. The authors study and analyze the DQDB performance and the fairness with both BWB-on and BWB-off for some influential parameters based on the simulation results. For light load condition, the performance approximation is established with remarkable accuracy. It is also shown that the BWB mechanism is effective on fairness only in overload condition. An effective BWB-MOD assignment method is examined. This method indicates the appropriate value of BWB-MOD to optimize the tradeoff between the average performance of the DQDB protocol and the fairness achieved by the BWB mechanism