Feedback Output Queuing: A Novel Architecture for Efficient Queuing Systems. 

Victor Firoiu, Xiaohui Zhang, Emre Gunduzhan.


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.