The bypass queue in fast packet switching

The telecommunications networks of the future are likely to be packet switched networks consisting of wide bandwidth optical fiber transmission media, and large, highly parallel, self-routing switches. Recent considerations of switch architectures have focused on internally nonblocking networks with packet buffering at the switch outputs. These have optimal throughput and delay performance. The author considers a switch architecture consisting of parallel plans of low-speed internally blocking switch networks, in conjunction with input and output buffering. This architecture is desirable from the viewpoint of modularity and hardware cost, especially for large switches. Although this architecture is suboptimal, the throughput shortfall may be overcome by adding extra switch planes. A form of input queuing called bypass queuing can improve the throughput of the switch and thereby reduce the number of switch planes required. An input port controller is described which distributes packets to all switch planes according to the bypass policy, while preserving packet order for virtual circuits. Some simulation results for switch throughput are presented