RED Revisited

摘要

One of the most promising active queue management schemes being proposed for deployment in the Internet is RED. However, research results on RED performance are highly mixed, especially in the field of tuning its parameters. In this paper, we revisit some features in RED and study them in greater details. We point out that RED in general does not possess proportional loss between flows as claimed and widely adopted in previous research. We suggest the generalization of PASTA and give proof for TCP flows. We also evaluate the performance of the Exponential Weighted Moving Average (EWMA) algorithm in RED. We find that EWMA in RED is an unbiased estimator of average queue-length, regardless of the weighting value ω_q. Finally, we propose the use of Fuzzy EWMA to RED (Fuzzy RED) to alleviate the inflexibility of RED tuning. We use simulations to evaluate the performance of Fuzzy RED and compare it with other versions of RED. Our simulations show that, in case of high work load, this mechanism can effectively reduce packet loss while maintaining high link utilization under different scenarios.