Patent ID: 7016350

Claim:
A data switching system having a plurality of virtual output queue ingress routers, a plurality of egress routers, a control unit, and a memory-less switching matrix for interconnecting selected ingress routers and egress routers, the ingress routers being arranged to receive data traffic segregated into equal sized cells having a header including an egress router output path address, to route the cells into virtual output queues in the ingress router in accordance with the egress router output path address and to generate connection requests for transmission to the control unit, the control unit being arranged to arbitrate among the connection requests and control the switching matrix to schedule the connections across the switch, wherein a separate queue is provided in each ingress router for time division multiplex traffic segmented into a plurality of standard cells and the control unit includes a time division multiplex connection unit arranged to override the normal arbitration procedure for each time division multiplex frame and to provide the switch connections for the cells of the time division multiplex frame, the control unit being arranged, in each of a plurality of arbitration periods, to determine whether the requests include requests compatible with said connections specified by the time division multiplex connection unit, and, if one or more such requests are found, to control the switching matrix to perform the connection specified by these requests, the control unit including a first pipeline stage performed by said time division multiplex connection unit, a second pipeline stage for satisfying any multicast requests compatible with the connections specified by the time division multiplex connection unit, and one or more stages for satisfying unicast requests compatible with the connections specified by the time division multiplex connection unit and by any satisfied multicast requests.