A novel numerical algorithm based on self-tuning controller to support TCP flows

Active queue management (AQM) is an effective method used in Internet routers for congestion control, and to achieve a trade off between link utilization and delay. The de facto standard, the random early detection (RED) AQM scheme, and most of its variants use average queue length as a congestion indicator to trigger packet dropping.This paper proposes a novel numerical algorithm based on self-tuning control circuit, called loss ratio and rate control RED (LRC-RED), to regulate the queue length with small variation and to achieve high utilization with small packet loss. This scheme is based on random early detection (RED) of the loss ratio and the total send rate control, and measures the latest packet loss ratio, then uses the latest packet loss ratio and the total input rate as complements to queue length in order to dynamically adjust packet drop probability. Furthermore, we also give a theoretical analysis of system stability and develop a simple, scalable and systematic guideline for the selection of feedback gains for the dynamic TCP/RED system to stabilize the queue length at a desirable level. Extensive simulations have been conducted with ns−2ns−2. The simulation results have demonstrated that the proposed LRC-RED algorithm outperforms the loss ratio-based RED (LRED) [C. Wang, B. Li, Y.T. Hou, K. Sohraby, Y. Lin, LRED: a robust active queue management scheme based on packet loss ratio, in: Proceedings of IEEE INFOCOM 2004, IEEE, 2004] algorithm in terms of stability, fast response time and robustness.