An Experimental Study of the Efficiency of Explicit Congestion Notification

Explicit Congestion Notification (ECN) is an addition to the Internet Protocol and the Transmission Control Protocol (TCP) which aims in improving the performance of TCP and other transport layer protocols. ECN is only meaningful when combined with bottleneck links that use Active Queue Management (AQM). Random Early Detection (RED) and other AQM mechanisms have been subject of criticism regarding their ability to improve the behavior of bottleneck links. This paper is an experimental study of Drop-Tail, RED and RED+ECN when operating over a constantly congested link. The paper studies the performance and the efficiency of TCP under constant congestion when using those methods and shows that ECN actually improves the efficiency of TCP without harming its performance.