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Many networking/computing applications require high speed switching for multicast traffic at the switch/router level to save network bandwidth. However, existing queueing based packet switches and scheduling algorithms cannot perform well under multicast traffic. While the speedup requirement makes the output queued switch difficult to scale, the single input queued switch suffers from the head of line (HOL) blocking, which severely limits the network throughput. An efficient yet simple buffering strategy to remove the HOL blocking is to use the virtual output queueing (VOQ), which has been shown to perform well under unicast traffic. However, it is impractical to use the traditional virtual output queued (VOQ) switches for multicast traffic, because a VOQ multicast switch has to maintain an exponential number of queues in each input port. We give a novel queue structure for the input buffers of a VOQ multicast switch by separately storing the address information and data information of a packet, so that an input port only needs to manage a linear number of queues. In conjunction with the multicast VOQ switch, we present a first-in-first-out based multicast scheduling algorithm, FIFO Multicast Scheduling (FIFOMS), and conduct extensive simulations to compare FIFOMS with other popular scheduling algorithms. Our results fully demonstrate the superiority of FIFOMS in both multicast latency and queue space requirement.
Date of Conference: 15-18 Aug. 2004