Mathematical Problems in Engineering
Volume 2005 (2005), Issue 6, Pages 617-640

Modelling and optimization of computer network traffic controllers

N. U. Ahmed, Bo Li, and Luis Orozco-Barbosa

School of Information Technology and Engineering, University of Ottawa, Ottawa K1N 6N5, ON, Canada

Received 28 February 2005

Copyright © 2005 N. U. Ahmed et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


During the past years, there has been increasing interest in the design and development of network traffic controllers capable of ensuring the QoS requirements of a wide range of applications. In this paper, we construct a dynamic model for the token-bucket algorithm: a traffic controller widely used in various QoS-aware protocol architectures. Based on our previous work, we use a system approach to develop a formal model of the traffic controller. This model serves as a basis to formally specify and evaluate the operation of the token-bucket algorithm. Then we develop an optimization algorithm based on a dynamic programming and genetic algorithm approach. We conduct an extensive campaign of numerical experiments allowing us to gain insight on the operation of the controller and evaluate the benefits of using a genetic algorithm approach to speed up the optimization process. Our results show that the use of the genetic algorithm proves particularly useful in reducing the computation time required to optimize the operation of a system consisting of multiple token-bucket-regulated sources.