Planificació de xarxa: algoritmes, experimentació i simulació

Abstract

Wide area networks experience a continuous increase of users and traffic. Due to the cost involved, networks cannot be continuously upgraded or expanded. Therefore, a better use of network resources is mandatory, by diverting traffic to less congested links. That is why research and implementation of new routing algorithms are needed, in order to optimize resources and to accommodate a greater amount of traffic on the same network. This requires either testing on a real network, with the technical risks and safety challenges this brings, or performing network simulations. In our case we decided to use the Net2Plan simulator, since it is a free open source software. In order to experiment with new traffic engineering algorithms, in the first part of the thesis we have studied the Net2Plan simulator and the main libraries it uses to understand how it works. Then we performed a comprehensive study of the performance of every algorithm that we are going to simulate, in order to be correctly interpret the results. Later we have carefully analyzed the topologies of RedIRIS and GÉANT with the aim of using them for the simulations, as they are two wide area networks from which we can obtain the necessary data, using the monitoring tools available at the website of each entity. We also used GÉANT's traffic matrix, obtained in previous degree theses. Finally we analyze the scenarios' structure used to simulate each routing algorithm and perform tests using the topology and traffic matrix of GÉANT in order to evaluate the performance of each algorithm metrics, representing the results graphically. The present thesis ends with conclusions, environmental impact and future lines of study. In this thesis, optimization of the network metrics RedIris and GÉANT are accomplished by the network algorithms application, by using Net2Plan simulations. All the data obtained from this thesis has an academic purpose, providing significant knowledge that can be helpful on network traffic engineering courses.

Les xarxes de comunicacions han experimentat un augment continu tant d'usuaris com de trànsit. Aquestes xarxes no poden ampliar-se constantment, raó per la qual és important fer recerca en l'optimització dels recursos, la disminució del cost i l'augment del seu rendiment. Per tant, és necessari l'estudi i implementació de nous algorismes de xarxa, amb l'objectiu de dissenyar, gestionar i planificar les xarxes per maximitzar la seva eficiència. Aquests algorismes poden proporcionar ajuda en el diagnòstic i maneig de la congestió a curt termini i, a llarg termini, poden convertir-se en un element clau en el disseny i dimensionat de la xarxa. L'estudi de nous algorismes implica la realització de proves per comprovar si ofereixen millores respecte a d'altres algorismes. Per a això, és necessari realitzar aquestes proves sobre la mateixa xarxa física, amb les dificultats tècniques i de seguretat que això comporta, o bé realitzar simulacions de xarxa amb l'ajuda d'algun dels programes existents. En el nostre cas hem decidit utilitzar el simulador Net2Plan, ja que és un programa lliure i de codi obert.