INTEGRATED QUEUING AND SCHEDULING FOR UNICAST AND MULTICAST TRAFFIC IN INPUT-QUEUED PACKET SWITCHES

摘要

This paper presents integrated queuing and scheduling for N × N input-queued packet switches that efficiently support both unicast and multicast traffic. In the integrated queuing, each input port maintains two sets of queues; one for unicast traffic and the other for multicast traffic. For unicast traffic, we deploy the well-known virtual output queuing scheme. For multicast traffic, we propose a novel queuing scheme in which a small number of load-balanced queues are allocated at each input port. The scheduling of unicast and multicast traffic is integrated within one switch fabric. Two specific issues are addressed regarding to the integrated scheduling: 1) the service ratio of unicast traffic to multicast traffic, and 2) the integration strategy between unicast and multicast scheduling. The first issue relates to the internal switch fabric bandwidth allocation. We prove that as long as the service ratio is chosen appropriately, a 100% throughput can be achieved. The second issue concerns how the unicast and multicast scheduling interact with each other. Two integration strategies are designed; they are light coupled and tight coupled strategies. Both strategies are able to achieve a low packet delay. The analytical and simulation results show that the proposed integrated queuing and scheduling performs well in the present of diverse traffic patterns.