Non-blocking memory-memory-memory Clos-network packet switch

Abstract

Buffered Clos-network switch, also referred as memory-memory-memory (MMM) Clos-network switch, is an alternative to single-stage switches to implement large-scale packet switches. In this paper, we unveil the head-of-line blocking problem of MMM Clos-network switches with switch modules implemented by buffered crossbars, which causes performance degradation. We propose a three-stage buffered Clos-network switch with per-output flow queues in the switch modules at the first two stages to avoid head-of-line blocking. The proposed switch, called the MMeM switch, achieves higher performance than an MMM buffered Clos-network packet switch. We show the performance improvement of the proposed MMeM switch under different traffic patterns.