EQEB-a multi-channel extension of the DQDB protocol with tunable channel access

The estimated queue expanded bus (EQEB) protocol, a multichannel extension of the distributed queue dual bus (DQDB) protocol, is discussed. In EQEB an individual node is assigned a fixed channel for reception but can transmit to any of the outgoing channels by local channel tuning or switching, thus increasing the total bandwidth of the network while reducing the node complexity. Four concepts associated with EQEB are introduced: local tunable channel access, global request counting, estimated delay queueing, and linear bandwidth balancing. Network simulations for 1024 nodes on 16 channels demonstrated that a throughput of ⩾0.8 per channel is achieved under heavily overloaded conditions. Fairness of access is demonstrated by proper selection of local parameters controlling the media access at each node