Implicit Service Differentiation using Deficit Round Robin

This paper describes and evaluates the performance of a modified deficit round robin scheduler called PDRR (for Priority DRR). In conjunction with per-flow admission control, PDRR allows the realization of implicit service differentiation where streaming and elastic flows are assured adequate performance without the need for explicit class of service marking or resource reservation. We show through simulation that PDRR is scalable and feasible since the number of flows to be scheduled remains less than a few hundred for any link speed. PDRR is also shown to provide very low latency for the packets of streaming flows as long as their rate is a relatively small fraction of the link rate.