Switch Expansion Architecture Using Local Switching Network

Absfrncf We propose a scheme for expanding switch modules to form a larger switch using the so-called focnl switching obtained by allowing bidirectional connection to the conventional three-stage Clos network switch. The performance of the proposed expansion architecture was compared to that of the conventional three-stage Clos network. We simulated 32x32 switching systems using two expansion architectures with the same switching strategy. Experiments show that average switching latency is reduced by up to 60% in the expansion using the local switching network compared to one using the conventional three-stage Clos network switch. The latency reduction is dependent on the ratio of the delay of switch fabric to that of port controller. Expansion using the local switching network reduces latency across the switching system. We assumed that the switching system switches variablesized packets since we studied this architecture for Gigabit Ethemet switch. While some of Gigabit Ethemet switching systems internally use the fixed-size switching, we decided to use the variable-size switching because of other problem such as resource utilization.