关键词: 平均变化率, 空闲长度, 队列, 丢包概率模型, 改正的数据包随机早期丢失算法（DRED）

Abstract: As the calculation of the packet loss probability is lack of accuracy without considering the self-similarity of the network flow, a new packet discard model based on the average changing rate of the packet enqueue rate and the ideal queue length is brought out, and it gives the corresponding algorithms—DRED algorithms. By introducing the state of the network flow into the calculation of the packet loss probability, it overcomes the drawback that the RED directly discards all the packets that will enqueue when the average length of queue between the maximum threshold and the maximum length, and the packet discard probability varies with the changes of the network traffic states. The?simulation results show that to adopt the DRED algorithms can make the calculation of the packet lose rate more accurate, the throughput of the network increases, the packet loss rate reduces and the network performance is improved, although the end-to-end delay increases slightly, but the delay jitter is relative smaller, compared with the RED algorithms.

Key words: average changing rate, ideal length, queue, packet discard model, Developed Random Early Detection（DRED）