Scalable two-stage clos-network switch and module-first matching

Clos-network switches were proposed as a scalable architecture for the implementation of large-capacity circuit switches. In packet switching, the three-stage Clos-network architecture uses small switches as modules to assemble a switch with large number of ports or aggregated ports with high data rates. However, the configuration complexity of packet Closnetwork switches is high as port matching and path routing must be performed. In the majority of the existing schemes, the configuration process performs routing after port-matching is achieved, and thus making port matching expensive in hardware and time complexity for a large number of ports. Here, we reduce the configuration complexity by performing routing first and port matching afterwards in a three-stage Clos-network switch. This approach applies the reduction concept of Clos networks to the matching process. This approach results in a feasible size of schedulers for up to Exabit-capacity switches, an independent configuration of the middle stage modules from port matches, a reduction of the matching communication overhead between different stages, and a release of the switching function to the last-stage modules in a three-stage switch. By using this novel matching scheme, we show that the number of stages of a Closnetwork switch can be reduced to two, and we call this the two-stage Clos-network packet switch.