Scheduling multicast traffic in a combined input separate output queued switch

Abstract

Although several promising multicast solutions have been proposed till now; however, the support of multicasting still remains notoriously difficult for switches or routers in networks because of the traffic expansion due to multicast replication. In this paper, we propose to use a Combined Input Separate Output Queued Switch (CISOQ for short) to achieve high performance when loaded with multicast traffic. By giving novel definitions for the waiting time and the queue occupancy of multicast cells, we extend the use of oldest cell first (OCF) and longest queue first (LQF) algorithms from the unicast-only traffic load to the multicast traffic load. Furthermore, we show that 100% throughput can be obtained by a CISOQ switch when it is scheduled by OCF and LQF without speedup or by any maximal matching algorithms, just used in the unicast-only traffic load before, with a speedup of 2. The only assumptions on the multicast traffic pattern are that it is multicast-admissible and SLLN and that it does not oversubscribe any inputs or outputs. As far as we know, this result is the first theoretical analysis of multicast traffic arrival process till now. © IFIP International Federation for Information Processing 2005.