Comparison of different congestion control strategies for low priority controllable traffic in packet switched backbone networks

Abstract

SUMMARYIt is expected that a signi"cant part of the data #ows of future multi-service packet switched backbone networks will use low priority, non-real-time data transmission services of the networks. The common bene"t for both user applications and network operators is that the data #ows of the low priority services could use the free capacity of the networks, after the load of higher priority data #ows. Congestion control methods are needed for these low priority data #ows to reach an optimal utilisation level of the networks, high throughput and low packet loss ratios. This kind of low priority data transmission service which adjusts the data rates of the data #ows according to the data rate changes of higher priority data #ows, but does not guarantee any speci"c service for these data #ows, is called a controlled load service. In this paper, we have compared the performance, e$ciency and scalability of four di!erent congestion control methods designed for the controlled load service. Two of these methods were based on very simple congestion control algorithms and the other two used relatively complex control algorithms based on control methods utilising computational intelligence. The principal aim of this study was to research how remarkable were the e!ects that the di!erent complexities of the congestion control methods had on the achieved level of service. The simulation tests indicate that the complexity of the methods clearly a!ects the performance and e$ciency of the methods.