Étude de l'équité du protocole TCP dans les réseaux multi-saut

Abstract

Recently, wireless mesh networks (WMNs) have been widely used. They are considered as a new technology that offers last-mile broadband Internet Access. WMNs are multi-hop networks which present many advantages such as the simplicity and the low cost of the deployment, the auto-formation, the reliability, etc. TCP is an important protocol and TCP traffic forms almost 90% of the whole Internet traffic. Therefore, we propose to analyse and evaluate the performance of TCP over multi-hop networks then we study the different ways to enhance its performance. The main topic that we deal with is the equity between TCP flows of the different sources. To do so, simulations are conducted using NS-2 simulator. We use a wired topology with a specific traffic to simulate the wireless nature of WMNs. Through an experimental study using a testbed we analyze the equity for wireless multi-hop networks. In WMNs, uplink traffic is destined to the gateway. According to the simulation results, we notice that the source nearest to the gateway takes advantage of most of the bandwidth so bandwidth inequity occurs. This inequity is related to the different RTTs and loss rates of the different sources. Furthermore, we also notice that the external delay to the mesh network can influence the TCP performance in terms of equity. To insure traffic balancing, we propose later to use DiffServ to avoid bandwidth starvation at the sources. We conclude that with DiffServ we reach a good equity level in the context of our study. The experimental results suggest that the equity has the same behaviour. We also reached a perfect equity using a destination-based mechanism that defines and controls the required bandwidth for each flow.

Date	29 Mar 2010
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Zbigniew Dziong (Supervisor) & Jean Charles Gregoire (Co-supervisor)