Extended Queue Backward Congestion Control Algorithms for Web Transfers

Abstract

Rapid development of telecommunication technologies and the ever growing network users demands have made network congestion a prominent problem in today's Internet. Congestion brings significant performance degradation to the network the Quality-of-Service (QoS). The Active Queue Management algorithms (AQM) are used to reduce congestion. In this paper, two AQM algorithms Extended Queue Management Backward Congestion Control Algorithm (EQMBCCA) and QMBCCA, which we have proposed earlier are taken in to consideration. QMBCCA makes use of ISQ (Internet Control Messaging Protocol (ICMP) Source Quench) signaling mechanism and also the CE (Congestion Experienced) bit whenever the average queue size crosses minimum threshold value. Both of them are redundantly used even for mild congestions. EQMBCCA introduces a configurable intermediate threshold value IntThres between the minimum and maximum values and generates ISQ signals only if the congestion crosses this threshold value. Therefore the generation of ISQ messages is significantly reduced here. There is also reliability since CE bits are also set in the packets once congestion occurs. The two algorithms are compared in terms of ISQ traffic, HTTP packet loss, fairness and average web object transfer delay for short lived web transfers. We have found that the performance of EQMBCCA is almost equal to that of QMBCCA and there is a significant reduction in the ISQ traffic in the reverse direction.