High-speed multicast scheduling in hybrid optical packet switches with guaranteed latency

In this paper, we study multicast scheduling in the OpCut switch, a recently proposed hybrid optical/electronic switching architecture for transmitting high-volume traffic in core networks and parallel computers. First, we present a multicast scheduling algorithm called Guaranteed Latency Multicast Scheduling (GLMS) that considers the schedule of each packet for multiple time slots. We show that GLMS has several desirable features, such as guaranteed latency for all transmitted packets and adaptivity to transmission requirements. To relax the time constraint on computing a schedule, we further propose a parallel and pipeline processing architecture for GLMS that distributes the scheduling task to multiple pipelined processing stages, with $(N)$ processors in each stage, where $(N)$ is the switch size. Finally, by implementing it with simple combination logic circuits, we show that each processor can finish the scheduling for one time slot in $(O(1))$ time complexity. We evaluate the performance of GLMS extensively against statistical traffic models and real Internet traffic, and the results show that the proposed GLMS algorithm can achieve very low average packet latency with minimum packet drop ratio.