A Comparison Study of End-to-End Delay Using Different Active Queue Management Algorithms

In high-speed networks supported by TCP/IP, congestion control algorithm plays an important role. Real time streaming media, such as video, audio conversations and movies on line, often are transmitted over the Internet. The dominant paradigm for congestion control in the Internet is based on the TCP friendliness. As the load on the network increases, it is critical to find the point at which congestion occurs. When congestion is about to happen, the network should be capable of reducing the rate at which the hosts send the data before the packets start being discarded. Random early detection (RED) algorithm is one such mechanism used at the router to control congestion in the network. It is programmed to monitor the queue length at the specific router. When it detects that congestion is imminent, it notifies the source to adjust its congestion window. The key principle in RED implementation is that, it notifies the source of congestion occurrence by dropping one of its packets. In this paper, we have illustrated the performance of RED and FIFO in the network in terms of end-to-end delay, which is one of the important parameters in the quality of service (QoS) of the network.

1. Introduction

QoS in the existing and emerging applications in the Internet has been a big challenge to the Internet programmer. Real time applications such as audio/video conversations and on demand movies are interactive, have delay constraints or require high throughput. There were many mechanisms proposed in the past to enable the internet to support applications with varying service requirements. These include admission control, active queue management algorithms and scheduling. Admission control is meant to prevent network overload so as to ensure service for applications already admitted. It is deployed at the network edges where a new flow is either admitted, when network resources are available or rejected otherwise. Active queue management has been proposed to support end-to-end congestion control in the Internet. The aim is to anticipate and signal congestion before it actually occurs. Scheduling determines the order in which the packets from different flows are served. The above mechanisms are building blocks of quality of service (QoS) architectures.