Asynchronous credit-based scheduling scheme for a multi-stage network

The multi-stage network based on the Clos network is widely used to build a scalable architecture for high-performance switches and routers. Many scheduling algorithms have been proposed to improve the performance of this architecture. Most high-speed switches and routers with a multi-stage architecture using a twice-matching scheduling algorithm, and "push" the packets to the egress by two-hop scheduling algorithms. These algorithms, however, can not schedule precisely and optimize the packet delay. In this paper, we present an efficient scheme called "asynchronous credit-based scheduling scheme" for scheduling both fixed-size or variable length packets on high-speed packet switches with a multi-stage architecture. The asynchronous credit-based scheduling scheme is a "pull" scheme which can achieve 100% throughput under uniform traffic with comparable delay performance and also support different QoS disciplines. It improves the effective utilization of each output port and significantly reduces the packet delay.