FAIRNESS UNDER SUSTAINED OVERLOAD IN A DQDB SUBNETWORK WITH ERASER NODES

摘要

The Distributed Queue Dual Bus (DQDB) protocol has been specified by the IEEE 802.6 committee as part of its standard for a Metropolitan Area Network.DQDB is based on 'OR' writing.However,by allowing erasing capabilities to some stations,its transmission capacity can be increased considerably.In this paper,we propose fairness criteria for the apportionment of throughput among the different stations for a DQDB subnetwork involving eraser nodes under sustained overload.These criteria are based on maximizing the minimum throughput available to any station.Idealistic values of capacity apportionment for each active station are analytically computed by a recursive procedure.These idealistic values provide a quantitative standard against which the fairness of proposed eraser node protocols may be assessed.A numerical example is used to provide a detailed demonstration of our method for capacity apportionment.