Congestion Control in Wide Area Networks

Abstract

This work studies the different congestion control algorithms for the gateways in wide area networks, which means the congestion control from the perspective of the network not the end system. It focuses on the Internet network because it is the largest wide area network allover the world.

It discusses the use of the modified RED-ECN congestion control algorithm (Random Early Detection, Explicit Congestion Notification) which can improve some of the disadvantages of using RED or of using ECN alone. The gateway can use the RED with ECN until the average queue size reaches certain threshold and then switch to use RED without ECN. In this case the gateway can avoid unnecessary packet drops and therefore avoid unnecessary delay in times of low level congestion, But ensures reliable delivery of congestion notification and reduces congestion collapse in times of high level congestion.

Simulation results were used to evaluate the performance of the network when using the proposed modified RED-ECN congestion control algorithm. It shows that using this algorithm can maintain the network in a region of low delay by minimizing congestion losses.