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 wormhole 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 wormhole switching coupled with the simpler and cheaper design makes it an attractive alternative. Simulation of a ( ) fat-mesh using this router suggests that clusters designed with appropriate bandwidth balance between links can provide good performance for different types of traffic.