Frame occupancy-based dispatching schemes for buffered three-stage Clos-network switches

The three-stage Clos-network switch architecture has attractive scalability features that makes it appealing as an alternative for scalable switches. However, scheduling packets in a Clos-network switch is complex. This complexity can be simplified by adding buffers to the first and third stages. By adding these buffers, the scheme used for dispatching packets from the first stage of the switch becomes important. Several dispatching schemes for Clos-network, without internal expansion, that deliver high throughput under uniform traffic model have been proposed. However, there is a need of dispatching schemes that provide high throughput under several admissible traffic patterns, including those with nonuniform distributions, with a small number of matching iterations and without internal expansion. In this paper, we propose two frame-occupancy based dispatching schemes to increase throughput performance in Clos-network switches without using internal expansion. We show that frame-occupancy based schemes deliver high throughput under uniform and nonuniform traffic patterns.