Feedback output queuing: a novel architecture for efficient switching systems

We consider the problem of providing QoS guarantees in a high-speed packet switch. As basic requirements, the switch should be scalable to high speeds per port, a large number of ports and a large number of traffic flows with independent QoS guarantees. Existing scalable solutions are based on virtual output queueing, which is computationally complex when required to provide QoS guarantees for a large number of flows. We present a novel architecture for packet switching that provides support for such QoS guarantees. A cost effective fabric with small external speedup is combined with a feedback mechanism that enables the fabric to be virtually lossless, thus avoiding packet drops indiscriminate of QoS flows. Through analysis and simulation, we show that this architecture provides accurate QoS support, has low computational complexity and is scalable to very high port speeds.