Fair access of multi-priority traffic to distributed-queue dual-bus

Abstract

Bandwidth balancing is accomplished to DQDB networks that handle multi-priority traffic by causing each node to throttle its own rate of transmission in accordance with the priority of the data that the node transmits. In accordance with one approach, each node limits its throughput to the product of a bandwidth balancing factor (which is a fraction that varies according to the priority level of data) and the unused bus capacity. When parcels of different priorities are received within each node, the parcels are processed in priority order. In accordance with another approach, all active parcels within a node are handled concurrently and receive some bandwidth. The throughput of each parcel in a node is limited to the product of the bandwidth balancing factor and the unused bus capacity. In accordance with still another approach, each traffic parcel limits it throughput to the product of the bandwidth balancing and the bus capacity unused by parcels of equal or higher priority. This scheme allocates bandwidth first to the higher-priority parcels, then allocates the leftovers to the lower-priority parcels. Lower-priority parcels have no effect on the steady-state throughputs of higher-priority parcels.