US Patent 6876629 Rate-controlled multi-class high-capacity packet switch

A packet switch includes ingress modules, egress modules, and a switch core. Packets of variable sizes may be divided into segments of predetermined sizes to facilitate switching within the switch core. The segmentation process may require null-padding which increases the flow rate within the switch. The segments are transferred from ingress to egress under flow-rate control based on inflating specified flow rates. Null padding is removed at egress. Ingress modules sort segments or packets according to their destination egress modules and egress modules sort segments or packets according to their ingress-module origin. Thus, segments of the same packet, and packets of the same stream, are properly concatenated as they appear in a logical buffer at egress. To enable growth of the packet switch to accommodate a very large number of ingress and egress modules, the switch implements a method of fast matching to schedule packet transfer across the switch core.