iRGRR: A fast scheduling scheme with less control messages for scalable crossbar switches

Abstract

This paper presents a scalable scheduling scheme, called iterative request-grant-based round-robin (iRGRR), for input-queued switches. Most traditional iterative scheduling schemes are based on a request-grant-accept process, such as PIM and iSLIP, and suffer from poor scalability due to the large latency in control message transmission. iRGRR overcomes this limitation by simplifying the execution process and reducing the scheduling overhead. It dramatically reduces the complexity of control messages from an order of O (N) to O (log N), and is thus a scalable solution for high port density switches. The simulation results show that iRGRR can achieve nearly the same performance as iSLIP under various traffic models, including uniform and non-uniform destination distributions. In addition, iRGRR provides better fairness and has lower implementation complexity than iSLIP. © Springer-Verlag Berlin Heidelberg 2004.