DiffServ simulations using the Network Simulator: requirements, issues and solutions

INTRODUCTION IP networks are destined to become the ubiquitous global communication infrastructure. An increasing number of different applications are continually conveyed by them causing a fragmentation of performance and service requirements. Continuous efforts have been made to develop a number of new technologies for enhancing Quality of Service capabilities. The DiffServ Architecture is the traffic management scheme defined by IETF to provide scalable services differentiation on the Internet. This thesis work aims to explore and to improve the simulations capabilities of the Network Simulator (NS), in addition the traffic management skills of that new architecture are evaluated. The main focus is on the versatility of building complete service models and on providing a wide range of performance parameters. Key contributions reached during this work are: firstly, an improved simulation module with a wider set of mechanisms, a better versatility of services definition and an extended set of performance parameters. Secondly, valuable test beds for mechanisms testing are set. In particular, a complete service model with a Premium Service targeted for conversational applications like Voice over IP, an Olympic Services sub-model targeted for relative services differentiation and a Best Effort Service for backwards compatibility is configured, relative traffic generators are set and performance parameters are monitored. In Chapter 1, a comparison among the former traffic management schemes is provided and the reasons that raised the need for a new model are pointed out. Chapter 2 introduces the DiffServ model as defined by IETF. The whole forwarding architecture is depicted, on the basis of standardized and draft documents. 5