Method and system for transmitting data packets buffered in a distributed queue on a communication network

摘要

A method and apparatus for a time division multiplex transmission of data packets from a plurality of access units in a communications network having a pair of oppositely directed unidirectional buses between which the access units are coupled, each access unit transmitting its data packets in empty time slots on a first of such buses. A queue is formed in each access unit of the data packets therein, and each time a further data packet is added to such queue a request flag is transmitted on the second bus. A count is kept of the number of request flags passing the access unit on the second bus, and such further data packet is assigned a priority value corresponding to the number of request flags existing at the time the further data packet is added to the queue. A distributed queue is thereby formed of all data packets in the network, a given data packet being transmitted in the first empty time slot on the first bus after a preselected number of free slots therein have passed its access unit, such preselected number being equal to the priority value of such data packet. Transmission is thereby achieved strictly in accordance with the first-in/first-out principle, so that the waiting period for a given data packet is not affected by the presence of subsequent data packets in other access units even though certain such subsequent data packets may already have reached the head of the queues in their access units.