A Clos-Network Switch Architecture Based on Partially-Buffered Crossbar Fabrics

Abstract

Modern Data Center Networks (DCNs) that scale to thousands of servers require high performance switches/routers to handle high traffic loads with minimum delays. Today's switches need be scalable, have good performance and-more importantly-be cost-effective. This paper describes a novel three-stage Clos-network switching fabric with partially-buffered crossbar modules and different scheduling algorithms. Compared to conventional fully buffered and buffer-less switches, the proposed architecture fits a nice model between both designs and takes the best of both: i) less hardware requirements which considerably reduces both the cost and the implementation complexity, ii) the existence of few internal buffers allows for simple and high performance scheduling. Two alternative scheduling algorithms are presented. The first is scalable, it disperses the control function over multiple switching elements in the Clos-network. The second is simpler. It places some control on a central scheduler to ensure an ordered packets delivery. Simulations for various switch settings and traffic profiles have shown that the proposed architecture is scalable. It maintains high throughput, low latency performance for less hardware used.