Distributed hierarchical scheduling and arbitration for bandwidth allocation

Abstract

According to the present invention there is provided a scheduling and arbitration process for use in a digital data switching arrangement of the type in which a central switch under the direction of a master control provides the cross-connections between a number of high-bandwidth ports to which are connected on the ingress side of the central switch a number of ingress multiplexers, one for each high-bandwidth input port and on the egress side a number of egress multiplexers, one for each high-bandwidth output port, each ingress multiplexer including a set of N input queues serving N low-bandwidth data sources and a set of M virtual output queues serving M low-bandwidth output data sources, characterized in that the scheduling and arbitration arrangement includes three bandwidth allocation tables, an ingress port table associated with the input queues and having N×M entries each arranged to define the bandwidth for a particular virtual output queue, an egress port table associated with the virtual output queues and having M entries each arranged to define the bandwidth allocation of a high-bandwidth port of the central switch to a virtual output queue and a central allocation table located in the master control and having (M×N)entries each of which specifies the weights allocated to each possible connection through the central switch.