Integrating unicast and multicast traffic scheduling in a combined input- and output-queued packet-switching system

The problem of scheduling multicast traffic in packet switches is considered, and existing solutions based on purely input- or output-queued switches are reviewed. These are based exclusively on FIFO input queues, and are thus prone to head-of-line blocking. Furthermore, unicast and multicast traffic are typically queued and scheduled separately. A new, combined input- and output-queued approach is presented that (a) eliminates head-of-line blocking by applying virtual output queuing, and (b) handles unicast and multicast traffic in an integrated, fair way without sacrificing performance. Implementation as well as performance simulation results of the proposed architecture are presented to demonstrate its feasibility.