A Simple Host Deflection Scheme for High-Speed LANs Using Wormhole Routing

Wormhole routing i s a s imple, low-cost switching scheme o f ten used f o r supercomputer interconnect ions. Recently, at also has been applied t o high-speed local area ne tworks t o support applications demanding high-datarate communicat ions , such as c luster computing. T h e drawback t o wormhole routing i s i t s low link e f i c i ency caused by w o r m blocking. T o overcome th is blocking problem, a t imeou t scheme was investigated in [3] by analytical modeling. In th is paper, we present t imeout s imula t ion results, showing t h e effect of packet size, propagation delay, and ne twork size. Furthermore, a s imple deflection scheme, which we call host deflection, i s introduced and tested. This s imple host deflection scheme requires only sma l l modifications t o t h e protocol and very little processing power f r o m t h e switches; i t improves the ne twork throughput significantly.