A method for controlling the access to a bus in a (dbdq) - network, comprising two buses and a distributed queue.

摘要

A distributed queue dual bus (DQDB) network has two, oppositely- directed, unidirectional busses. A node with data to send on one bus, can request access to that bus, by sending a bus request signal to all nodes upstream on the bus. The bus request signal is sent to the nodes as part of the traffic flowing on the second bus. Each node counts the number of successive bus request signals transported on the second bus. In a multiple priority system, multiple counts are maintained, one for each priority level. When a given or local node detects an idle slot on the first node, it may write data into that slot if there are no pending downstream access requests of higher priority and if the local node has allowed enough idle slots to pass since its last write operation to service access requests existing at the time of that operation at the same or higher priority levels.