Improvements in or relating to asynchronous transfer mode communication systems

摘要

An ATM communication system comprising an ATM switch 1 having a plurality of input ports and a plurality of output ports, each of the said input ports being fed from an input port server 2, 3,4, and each of the said output ports being arranged to feed an output port server 8. The input port servers each have a plurality of buffer stores A, B...Z, one for each of the output ports to which said output port data is transmitted through the switch. Each buffer store in the input port servers is arranged to interrogate the output port server with which it communicates by means of a bandwidth request before the transmission of data, thereby to determine whether output port server data handling capacity is available, whereby ATM switch operation during periods of peak traffic is facilitated. The system includes a queuing arrangement for bandwidth requests received during periods when there is no available bandwidth capacity, the arrangement being such that requests are released in a predetermined order when capacity becomes available.