STUMM : A COMPARISON OF BLOCKING AND NON - BLOCKING NETWORKS 3 Output Link Input Link Ring Buffer Output

SUMMARY This paper presents the results of a simulation study of blocking and non-blocking switching for hierarchical ring networks. The switching techniques include wormhole, virtual cut-through, and slotted ring. We conclude that slotted ring network performs better than the more popular wormhole and virtual cut-through networks. We also show that the size of the node buuers is an important parameter and that choosing them too large can hurt performance in some cases. Slotted rings have the advantage that the choice of buuer size is easier in that larger than necessary buuers do not hurt performance and hence a single choice of buuer size performs well for all system conngurations. In contrast, the optimal buuer size for virtual cut-through and wormhole switching nodes varies depending on the system con-guration and the level in the hierarchy in which the switching node lies.