Investigating QoS support for traffic mixes with the MediaWorm router

With the increasing use of clusters in real-time applications, it has become essential to design high performance networks with quality of service (QoS) guarantees. In this paper, we explore the feasibility of providing QoS in worm-hole switched routers, which are otherwise well known for designing high performance interconnects. In particular, we are interested in supporting multimedia video streams, in addition to the conventional best-effort traffic. The proposed MediaWorm router uses a rate-based bandwidth allocation mechanism, called Virtual Clock, to schedule network resources for different traffic classes. Our simulation results on an 8-port router indicate that it is possible to provide jitter-free delivery to VBR/CBR traffic up to an input load of 70-80% of link bandwidth, and the presence of best effort traffic has no adverse effect on the real-time traffic. Although the MediaWorm router shows a slightly lower performance than a pipelined circuit switched (PCS) router, commercial success of worm-hole switching coupled with the simpler and cheaper design makes it an attractive alternative. Simulation of a (2/spl times/2) fat-mesh using this router suggests that clusters designed with appropriate bandwidth balance between links can provide good performance for different types of traffic.