EFFECTIVE ERASURE NODE ALGORITHM FOR SLOT REUSE IN DQDB

The distributed queue dual bus (DQDB) protocol, which has been specifi ed by the IEEE 802.6 as the metropolitan area networks (MANs) standard , has an undesirable feature in that already received (i.e. read) busy slots continue to propagate downstream unnecessarily. The use of spec ial nodes, known as erasure nodes, allows conversion of read slots to empty, so that down-stream nodes may reuse these slots. This should re sult in an increase of the total throughput of the network. The author s introduce and evaluate the performance of an erasure node algorithm. The algorithm keeps track of past activities on both buses to effecti vely balance the slot erasure and the request cancellation functions. It is shown that this algorithm possesses a number of features which m ake it superior to existing algorithms.