Fair, efficient and low-latency packet scheduling using nested deficit round robin

In the emerging high-speed integrated-services packet-switched networks, packet scheduling algorithms in switches and routers play a critical role in providing the quality of-service (QoS) guarantees required by many applications. We present a new scheduling discipline called nested deficit round robin (Nested-DRR), which is fair, efficient and in addition has a low latency bound. Nested-DRR splits each DRR round into one or more smaller rounds, within each of which we run a modified version of the DRR scheduling discipline. In this paper, we analytically prove that Nested-DRR results in a significant improvement in the latency bound in comparison to DRR, and in addition preserves the good properties of DRR such as the per-packet work complexity of O(1). Nested DRR also has the same relative fairness bound as DRR.