A 3-stage interconnection structure for very large packet switches

The authors propose a three-stage broadband packet-switch architecture for a future central office with more than 16,000 ports. The switch is constructed by interconnecting many small independent switch modules, which can be implemented using modifications of various well-studied switch-fabric designs. Multiple paths are provided for each input-output pair, and the channel-grouping technique is used to decrease delay and increase throughput. A datagram packet-routing approach is adopted in order to eliminate the table lookup that will be required by virtual-circuit routing. Ways of guaranteeing the sequence integrity of packets are discussed. It is estimated from performance analyses that 32,768-port switches can be constructed and can perform well based on switch fabrics of no more than 128 ports.