Performance Evaluation of Routing Schemes in Data Center Clos Networks

A number of new Clos data center networking fabrics have been proposed recently by using commodity offthe-shelf hardware. In Clos networks, randomized routing is typically used to achieve load balance. However, with typical communication patterns, pure randomized routing design cannot fully exploit bandwidth provided by Clos topologies. This paper strives to evaluate the performance of both randomized routing and its alternatives. As an incremental improvement, periodic path renewal is discussed first. We then discuss adaptive routing, together with its implementation consideration and costs. To reduce overhead of pure adaptive routing, a mixed routing scheme is also discussed. Through detailed discussions and comprehensive evaluations, we provide designers with useful insight and a range of options for configuring the routing scheme.