Designing Buffer Capacity of Crosspoint-Queued Switch

Abstract : We use both theoretical analysis and simulations to study crosspoint-queued(CQ) buffer size’s impact on CQ switch’s throughput and delay performance under different traffic models, input loads, and scheduling algorithms. In this paper, 1) we present an exact closed-form formula for the CQ switch’s throughput and a non-closed-form but convergent formula for its delay using static non-work-conserving random scheduling algorithms with any given buffer size under independent Bernoulli traffic; 2) we show that the above results can serve as a conservative guidance on deciding the needed buffer size in pure CQ switches using work-conserving algorithms such as random, under independent Bernoulli traffic. Furthermore, our simulation results under real-trace traffic show that simple round-robin and random work-conserving algorithms can achieve quite good throughput and delay performance with feasible crosspoint buffer size. Our work reveals the impact of buffer size on CQ switches’ performance and provides a theoretical guidance on designing the buffer size in pure CQ switch, which is an important step towards building ultra-high-speed switching fabrics.