Applied Mathematics & Information Sciences

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Fair bandwidth sharing and differentiated drop precedence are two key QoS provisioning in the Internet. However, they both are studied separately. In the paper, we propose a simple active queue management scheme that deals with fair bandwidth sharing and differentiated drop precedence at the same time namely priority-aware fair queueing (PAFQ). PAFQ uses a dynamic threshold to keep up with traffic variations and hence it can efficiently discriminate non-aggressive flows from aggressive flows. Furthermore, a swap policy conditionally exchanges the records of current queue lengths of both compared packets from the same flow by considering respective drop precedence. Accordingly, this policy provides differentiated drop precedence within a flow. Besides, a mark policy is used to selectively mark a packet with the maximum count of current queue length that contributes to achieve fair bandwidth sharing among competing flows. When a marked packet reaches at the head of FIFO buffer, it will be discarded directly. Simulation results validate that the PAFQ is able to provide excellent fair bandwidth sharing and differentiated drop precedence under a variety of traffic conditions. In addition, it keeps average queue lengths low.