iRGRR/PM: A New Packet Scheduling Scheme for High-Speed Crossbars

iRGRR(iterative Request-Grant-based Round-Robin) is a scheduling algorithm for input-queued crossbars, which has many good features, such as simple, scalability and fine performance. This paper proposes a new packet scheduling scheme based on iRGRR, called iRGRR/PM (iRGRR with Packet Mode), for high-speed crossbars. iRGRR/PM algorithm is appropriate to schedule IP packet, and can be used in routers with high-speed and large capacity. Compared to iRGRR, iRGRR/PM not only simplifies the design of packet output reassembly module, but also improves the bandwidth utilization of crossbar. The relation of packet delay between two algorithms is briefly analyzed, and simulation studies is done in detail. The results show that iRGRR/PM achieves higher throughput under the same circumstances, especially, reaches 100% throughput under nonuniform traffics. In addition, iRGRR/PM provides better performance of delay for larger packets.