<p>This thesis is an experimental study to evaluate the performance of different routing protocols in commonly deployed scenarios. This study mainly focuses on how much time each protocol consumes while recovering from a link-loss. It provides a guide line for the best routing solutions for ISPs, individual organizations or other types of providers which are engaged in providing reliable real-time communications to their subscribers. Such communications may include vehicle trafficking data, online TV programs (IPTV), voice over IP telephony (VoIP), weather forecasts, tracking systems and many other services which totally depend upon the reliability of real-time data streams, where any major loss in received data may bring significant negative results in the integrity of the entire application.</p><p>This work experimentally observes and tracks the loss of UDP packets when changes in the network topology occur. In order to make this observation in real network topologies, a custom-designed software tool has been developed. The tool is capable of delivering enough resources to a tester in evaluating the performance of routing protocols. All the test results derived from the software tool are statistically evaluated and on the basis of the outcome a better proposition can be provided to network administrators which face inconsistent topological issues.</p>

The Internet traffic is constantly increasing following the emergence of new network applications like social networks, peer-to-peer, IP phone or IP television. In addition, these new applications request better path availability and path quality. Indeed the efficiency of these applications is strongly related to the quality of the underlying network. In that context network operators make use of traffic engineering techniques in order to improve the quality of the routes inside their network, but also to reduce the network cost of increased traffic handling with a better utilization of existing resources. This PhD thesis covers several topics of Traffic Engineering and Fast Restoration in IP/MPLS networks. Our first contribution is related to the definition of a well-engineered network. In the literature mathematical formulation of Traffic Engineering (TE) requirements are very diverse. We have thus performed a comparative study of many objective functions, in order to differentiate them and choose in a rational way the one that best reflects Traffic Engineering goals. We have also designed a method approaching optimal TE, whereby we divide the traffic matrix in N sub-matrices and route them independently, based on the derivatives of the objective function. The second topic addressed in this work concerns link weight optimizers (LWOs). Link weight optimization is the traffic engineering {it "standard"} technique in networks running link state routing protocols (which are widely used in transit networks). These link weight optimizers suffer from several limitations due to the BGP (Border Gateway Protocol) Hot-Potato rule, which is basically not considered by such optimizers. Therefore we have proposed a BGP-aware link weight optimization method that takes problematic Hot-Potato effects into account, and even turns them into an advantage. We have also studied how LWOs behave in big networks which have to use BGP route reflectors. Finally we have studied whether forwarding loops can appear or not when traffic is split among multiple equivalent egress routers, an optional BGP feature that we did use in our Hot-Potato aware LWO. Our last contribution concerns network resilience. We have proposed a solution for a rapid recovery from a link or node failure in an MPLS network. Our solution allows a decentralized deployment combined with a minimal bandwidth usage while requiring only reduced amount of information to flood in the network. This method is the first that makes possible a decentralized deployment combined with an optimal resource consumption. To easily simulate and test the methods proposed in this work, we have also contributed to the development of TOTEM - a TOolbox for Traffic Engineering Methods.

The well-known Dijkstra's algorithm uses weights to determine the shortest path. The focus here is instead on the opposite problem, does there exist weights for a certain set of shortest paths? OSPF (Open Shortest Path First) is one of several possible protocols that determines how routers will send data in a network like the internet. Network operators would however like to have some control of how the traffic is routed, and being able to determine the weights, which would lead to the desired shortest paths to be used, would be a help in this task.The first part of this thesis is a mathematical explanation of the problem with a lot of examples to make it easier to understand. The focus here is on trying to combine several routing patterns into one, so that the result will be fewer, but more fully spanned, routing patterns, and it can e.g. be shown that there can't exist a common set of weights if two routing patterns can't be combined.The second part is a program that can be used to make several tests and changes to a set of routing patterns. It has a polynomial implementation of a function that can combine routing patterns. The examples that I used to combine routing patterns, showed that this will increase the likelihood of finding and significantly speed up the computation of a “valid cycle”. / Egentligen 30p/45hp, men det fanns inte som alternativ.

This thesis is an experimental study to evaluate the performance of different routing protocols in commonly deployed scenarios. This study mainly focuses on how much time each protocol consumes while recovering from a link-loss. It provides a guide line for the best routing solutions for ISPs, individual organizations or other types of providers which are engaged in providing reliable real-time communications to their subscribers. Such communications may include vehicle trafficking data, online TV programs (IPTV), voice over IP telephony (VoIP), weather forecasts, tracking systems and many other services which totally depend upon the reliability of real-time data streams, where any major loss in received data may bring significant negative results in the integrity of the entire application. This work experimentally observes and tracks the loss of UDP packets when changes in the network topology occur. In order to make this observation in real network topologies, a custom-designed software tool has been developed. The tool is capable of delivering enough resources to a tester in evaluating the performance of routing protocols. All the test results derived from the software tool are statistically evaluated and on the basis of the outcome a better proposition can be provided to network administrators which face inconsistent topological issues.

<p>The well-known Dijkstra's algorithm uses weights to determine the shortest path. The focus here is instead on the opposite problem, does there exist weights for a certain set of shortest paths? OSPF (Open Shortest Path First) is one of several possible protocols that determines how routers will send data in a network like the internet. Network operators would however like to have some control of how the traffic is routed, and being able to determine the weights, which would lead to the desired shortest paths to be used, would be a help in this task.The first part of this thesis is a mathematical explanation of the problem with a lot of examples to make it easier to understand. The focus here is on trying to combine several routing patterns into one, so that the result will be fewer, but more fully spanned, routing patterns, and it can e.g. be shown that there can't exist a common set of weights if two routing patterns can't be combined.The second part is a program that can be used to make several tests and changes to a set of routing patterns. It has a polynomial implementation of a function that can combine routing patterns. The examples that I used to combine routing patterns, showed that this will increase the likelihood of finding and significantly speed up the computation of a “valid cycle”.</p> / Egentligen 30p/45hp, men det fanns inte som alternativ.

Les opérateurs de réseaux de télécommunications accordent une importance toute particulière à la gestion des pannes. L'implication de l'humain dans la prise de décision et l'analyse d'une quantité énorme d'alarmes et d'informations, ainsi que le caractère réactif des mécanismes de gestion des pannes, ne permettent pas la réactivité nécessaire à une gestion optimale des incidents. Pour pallier ce problème, cette thèse s'intéresse à des mécanismes proactifs qui anticipent les pannes afin d'améliorer l'efficacité de leur gestion. La mise en oeuvre, dans les équipements, de composants autonomes capables d'analyser en permanence l'état de santé du réseau permettrait de fournir une information en temps réel sur le risque de panne, nécessaire au déploiement de nouveaux mécanismes d'autoréparation proactifs. La première partie de cette thèse est donc consacrée à la définition des composants architecturaux indispensables à l'introduction de fonctions d'autoréparation proactives. Dans un deuxième temps, nous étudions et analysons en détail trois mécanismes d'autoréparation proactifs exploitant une information de risque de panne. Le premier mécanisme a pour objectif d'accélérer la convergence des protocoles de routage à état de lien en adaptant la fréquence d'envoi des messages de détection de pannes en fonction du risque de panne. Le deuxième mécanisme modifie dynamiquement les métriques de routage afin de détourner le trafic des équipements risqués et de minimiser l'impact d'une panne sur le trafic. Enfin, le dernier mécanisme s'attache aux dispositifs de protection et de restauration du protocole GMPLS afin d'adapter dynamiquement la consommation des ressources, aux risques encourus

The aim of the diploma thesis is to choose network simulator suitable for network technologies laboratory tasks for educational use. Theoretical part of thesis describes basics of network communication, addressing, reference models. Thesis also describes standards Wi Fi, Ethernet and routing protocol OSPF - technologies which are discussed in laboratory tasks. The practical part of diploma thesis describes a few available network simulators suitable for creating two laboratory tasks. Finally, the NS-3 simulator was chosen. Both laboratory tasks include theoretical introduction, detailed description of source code, individual tasks, expected outputs and control questions which senses understanding of discussed technologies.

This masters'sthesis deals with graph theory and utilization of this theory for design and optimization of data network structures. Introduction chapter describes graph theory in general view, i.e. fundamental terms used for graph description, graph distinguishing, etc. Next part describes graph algorithms, for example a shortest path finding. After this I write about actual routing protocols where the graph algorithms are used. Last but one part deals with queuing theory and final part describes practical presentation of using graph theory for design and optimization of data network structure in Matlab programme environment.

Purpose of this master thesis was to explain simulation of real network, point to the imperfection during these simulations and try to find out technologies and solutions that could improve credibility of simulation. For this purpose, network simulator ns-3 has been chosen which supports direct code execution together with Quagga software suite. Master thesis describes internet protocol IPv4, UDP protocol, basics of routing and detailed explanation of OSPF routing protocol. Focus in this thesis is also on general description of simulation, its kinds and detail explanation of discrete simulation that is used by ns-3 simulator. Next chapter explains theory of ns-3 simulator, its development, conceptual overview and objects. Direct code execution and Quagga that both help improve credibility of simulation, are described in last chapter of theoretical part of thesis. In practical part of thesis is explained how to install and configure all three implemantaions of ns-3 simulator on Ubuntu, linux distribution. On the basis of obtained knowledge, the simulation model has been designed, also there has been given detailed explanation of how to create new model of simulation and how to analyze its results for all implementation.

Wireless mobile ad-hoc networks consist of a collection of peer mobile nodes that form a network and are capable of communicating with each other without help from stationary infrastructure such as access points. The availability of low-cost, com-modity network interface cards (NICs) has made the IEEE 802.11 medium access control (MAC) protocol the de facto MAC protocol for wireless mobile ad-hoc net-works, even though it is not optimal. The IEEE 802.11 MAC protocol is designed to have stations share a single channel in a given network. However, many of the IEEE 802.11 physical (PHY) layer specifications define multiple channels and allow the simultaneous, non-interfering use of some of these channels. Therefore, multiple communications can occur at the same time, offering the opportunity to increase the effective network capacity. We present an innovative routing protocol that utilizes multiple channels to im-prove the performance of wireless ad-hoc networks. The basic idea of the protocol is to use multiple channels so that multiple useful transmissions can occur simultane-ously, thus increasing network capacity. The proposed scheme requires minor changes to existing proactive ad-hoc routing protocols and no modifications to the current IEEE 802.11 MAC protocol. To reduce inefficiencies due to periodic updates in the proactive routing protocols, the proposed scheme divides the network layer into control and data planes. Nodes send routing updates using the control channel and user packets using the data channel. To demonstrate the multi-channel routing scheme, we extend the Destination-Sequenced Distance-Vector (DSDV), Open Shortest Path First-Minimal Connected Dominating Set (OSPF-MCDS), and Optimized Link State Routing (OLSR) protocol to multiple channel (MC) versions, denoted as DSDV-MC, OSPF-MCDS-MC, and OLSR-MC, respectively. Simulation results for DSDV-MC, OSPF-MCDS-MC, and OLSR-MC are presented and experimental results for OLSR-MC are presented. Simulation results indicate that DSDV-MC and OSPF-MCDS-MC effectively exploit multiple channels to improve network capacity. Goodput, the throughput consider-ing only useful error-free packets, increases with an increased number of available channels as the number of nodes and network load increase in both single-hop and multiple-hop networks. Experimental results with OLSR-MC also support that the proposed scheme increases network capacity without modification to the MAC proto-col in a real implementation. Although simulation and experimental results show that proposed scheme im-proves network capacity by exploiting multiple channels, problems exist with channel distribution. We introduce a new metric, the Channel Distribution Index (CDI) to in-vestigate these issues. The CDI indicates the fairness of the channel distribution. We identify the channel convergence problem, where a particular channel is over-utilized, and propose a channel reallocation scheme to mitigate the impact of the channel convergence problem using the CDI. / Ph. D.