The Control of Burstiness in Fair Queueing Scheduling

Bennett and Zhang [4] demonstrated the existence of large discrepancies between the service provided by the packet-based WFQ system and the fluid GPS system. As demonstrated in [4] these discrepancies can cause cycles of bursting. Such inaccuracy and bursty behavior significantly and adversely affect both best-effort and real-time traffics. The WFQ algorithm [4] overcomes this difficulty but its computational complexity is high relatively to other scheduling algorithms. Those algorithms, in contrast, are subject to the burstiness problem. This paper studies the issue of bursty transmission in packet scheduling algorithms. We propose the Burst-Constrain Fair-Queueing (BCFQ) algorithm, a packet scheduler that achieves both high fairness and low burstiness while maintaining low computational complexity. We also propose a new measure (and criterion) which can be used for evaluating the burstiness of arbitrary scheduling algorithms. We use this measure and demonstrate that BCFQ possesses the desired properties of fairness and burstiness.