A Research Of Improved Queue Fairness Based On RED Algorithm

In this paper, It gives a general introduction to the network congestion control. It is introduced the phenomenon and the cause of network congestion, discussed the research and development of congestion control strategies, and indicated that fairness is one of the important indexes that measure QoS. When many flows share the same bottleneck link, it can compete for limited network resources and result in extreme unfairness among data flows. The paper discusses that a faw factors can influent the bandwidth allotment of the TCP flows. In the light of the defect of the RED algorithm , presents two algorithm of improved queue fairness: QRED algorithm and DHRED algorithm,and by simulation we proved these algorithm are superior to the RED algorithm.QRED can effectively resolve the fairness problem that the flows adopt different packet size, the algorithm drops the arriving packets of each flow with different probability, and makes the link bandwidth allot fairly to the different flows. So It guarantees the network in the fairness of the bandwidth, and cancels the influence of the packet size to the network performance. By simulation it validates that performance of QRED is better than that of RED and DropTail.Under the coexistent environment of the normal TCP flows, non-TCP friendly flows and non-response flows, a DHRED algorithm is proposed to adjust the number of packet drops based on packet drop history, adopt the combined drop metrics to distinguish the high bandwidth flows.