International Business Machines Corporation

Johann R Muller

Erwin A Zurfluh

Werner K Bux

Mehdi M Nassehi

Pitro A Zafiropulo

A protocol and format for multiple accessing and transporting information in a Distributed Queue Dual Bus communications network includes count field in which stations can reserve multiple time slots for transporting data.

Method and apparatus for distributed queue multiple access in a

A distributed queue multiple access technique is disclosed for a system comprising two counterflowing transmission busses (A,B), plural stations (i, j) connected between them, and a headend station generating slots on the first one (A) of the busses; each station transmitting access requests on the second one (B) of the busses and determining its right to transmit data in slots on the first bus on the basis of access requests it has seen. Each station maintains a FIFO queue (41) for sequential storage of numbers representing external (EXT-REQ) and local (LOC-REQ) access requests. To achieve correct timing between access requests entering the queue from the second bus and respective free slots passing a station on the first bus, a station-individual delay is introduced by maintaining in a FIFO delay storage (71) a specific number of entries. This results in an equally fair treatment for all stations, and guarantees the availability of consecutive free slots for any station which requested them.

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Langnau, Switzerland

Johann R Muller