Packet-loss-robust load-balancing switch with distributed extended cross-point queues

Abstract

A packet switch architecture and a method for load-balancing are described, which involve no centralised schedulers. The method is implemented by distributing extended cross-point queues (a three-dimensional structure) over all elements of the switch and deploying pollers to append packets and to select the queues to be served, together with simple local work-conserving schedulers. The queue structure is such that it renders the proof that no packet will be mis-sequenced trivial. The architecture is practical and shows enhanced performance compared with other state-of-the-art load-balancing architectures, not only for the average delay but also for the distribution of individual delays, the latter being measured by a custom tool that compares the performance of the architecture to the ideal operation of an output queued switch. The queue structure permits the fair penalisation of only the offending input–output flows within the switch in the case of buffer overflow. The basic scheme is enhanced to avoid improper operation in the presence of packet drops, a problem that reintroduces mis-sequencing and that has not been properly addressed in the class of architectures that use pollers to distribute packets.