Choice of Inner Switching Mechanisms in Terabit Router

Abstract

More and more attention is focused on direct interconnection networks when designing the switching fabrics in the terabit routers. Various switching mechanisms are proposed for multi-computer systems, which also rely on direct interconnection networks between processors to support the messages passing mechanism. But it remains unknown which one is more suitable for fabrics in the terabit routers. Based on the requirements of terabit class routers we made analysis and simulations on various switching mechanisms, such as store and forward, wormhole switching, virtual cut through switching and pipelined circuit switching. The results show that virtual cut through exhibits superior performance characteristics over other switching mechanisms under various conditions. Simulations of the performances of virtual cut through shows that larger buffer, longer flit and more virtual channels help to sustain higher throughput at the cost of increasing latency.