Enhanced border gateway protocol in NS- 2 by adding the hot potato functionality based on real network

The rapid growth of the Internet has made the issue of ensuring reliability and redundancy a big challenge. Studies of these issues using Traffic Engineering and simulation have been extensively done. There has been substantial interest from researchers in the development and contribution of modules in NS-2. Most studies have not taken into account real traffic parameters in their simulation models. Also, there is no comprehensive model consisting of Border Gateway Protocol (BGP) and Hot Potato (HP) routing in the NS-2 network simulator based on real networks. In this paper, Integrated Model is introduced consisting of HP algorithm and BGP integrated into the NS-2 network simulator. The integrated model is then used to simulate the infrastructure of a real production network using actual captured traffic data parameters. The network is modeled with a baseline topology where 5 main nodes were connected together, with redundant links for some nodes. The simulations were repeated for link failures. HP helps in improving the node which experiences a link failure to select shorter distance route to egress router. In the case of a link failure, HP switching time between the links is 0.05 seconds. The integrated model performance was evaluated by comparing trace file before and after link failure or by adding nodes (up to 32). The parameters used for comparison are the packets loss, delay and throughput. The integrated model error percentage obtained for packets loss is 0.025%, delay 0.013% and throughput 0.003%

Aspects of proactive traffic engineering in IP networks

To deliver a reliable communication service over the Internet it is essential for the network operator to manage the traffic situation in the network. The traffic situation is controlled by the routing function which determines what path traffic follows from source to destination. Current practices for setting routing parameters in IP networks are designed to be simple to manage. This can lead to congestion in parts of the network while other parts of the network are far from fully utilized. In this thesis we explore issues related to optimization of the routing function to balance load in the network and efficiently deliver a reliable communication service to the users. The optimization takes into account not only the traffic situation under normal operational conditions, but also traffic situations that appear under a wide variety of circumstances deviating from the nominal case. In order to balance load in the network knowledge of the traffic situations is needed. Consequently, in this thesis we investigate methods for efficient derivation of the traffic situation. The derivation is based on estimation of traffic demands from link load measurements. The advantage of using link load measurements is that they are easily obtained and consist of a limited amount of data that need to be processed. We evaluate and demonstrate how estimation based on link counts gives the operator a fast and accurate description of the traffic demands. For the evaluation we have access to a unique data set of complete traffic demands from an operational IP backbone. However, to honor service level agreements at all times the variability of the traffic needs to be accounted for in the load balancing. In addition, optimization techniques are often sensitive to errors and variations in input data. Hence, when an optimized routing setting is subjected to real traffic demands in the network, performance often deviate from what can be anticipated from the optimization. Thus, we identify and model different traffic uncertainties and describe how the routing setting can be optimized, not only for a nominal case, but for a wide range of different traffic situations that might appear in the network. Our results can be applied in MPLS enabled networks as well as in networks using link state routing protocols such as the widely used OSPF and IS-IS protocols. Only minor changes may be needed in current networks to implement our algorithms. The contributions of this thesis is that we: demonstrate that it is possible to estimate the traffic matrix with acceptable precision, and we develop methods and models for common traffic uncertainties to account for these uncertainties in the optimization of the routing configuration. In addition, we identify important properties in the structure of the traffic to successfully balance uncertain and varying traffic demands

Une architecture parallèle distribuée et tolérante aux pannes pour le protocole interdomaine BGP au cœur de l’Internet

L’augmentation du nombre d’usagers de l’Internet a entraîné une croissance exponentielle dans les tables de routage. Cette taille prévoit l’atteinte d’un million de préfixes dans les prochaines années. De même, les routeurs au cœur de l’Internet peuvent facilement atteindre plusieurs centaines de connexions BGP simultanées avec des routeurs voisins. Dans une architecture classique des routeurs, le protocole BGP s’exécute comme une entité unique au sein du routeur. Cette architecture comporte deux inconvénients majeurs : l’extensibilité (scalabilité) et la fiabilité. D’un côté, la scalabilité de BGP est mesurable en termes de nombre de connexions et aussi par la taille maximale de la table de routage que l’interface de contrôle puisse supporter. De l’autre côté, la fiabilité est un sujet critique dans les routeurs au cœur de l’Internet. Si l’instance BGP s’arrête, toutes les connexions seront perdues et le nouvel état de la table de routage sera propagé tout au long de l’Internet dans un délai de convergence non trivial. Malgré la haute fiabilité des routeurs au cœur de l’Internet, leur résilience aux pannes est augmentée considérablement et celle-ci est implantée dans la majorité des cas via une redondance passive qui peut limiter la scalabilité du routeur. Dans cette thèse, on traite les deux inconvénients en proposant une nouvelle approche distribuée de BGP pour augmenter sa scalabilité ainsi que sa fiabilité sans changer la sémantique du protocole. L’architecture distribuée de BGP proposée dans la première contribution est faite pour satisfaire les deux contraintes : scalabilité et fiabilité. Ceci est accompli en exploitant adéquatement le parallélisme et la distribution des modules de BGP sur plusieurs cartes de contrôle. Dans cette contribution, les fonctionnalités de BGP sont divisées selon le paradigme « maître-esclave » et le RIB (Routing Information Base) est dupliqué sur plusieurs cartes de contrôle. Dans la deuxième contribution, on traite la tolérance aux pannes dans l’architecture élaborée dans la première contribution en proposant un mécanisme qui augmente la fiabilité. De plus, nous prouvons analytiquement dans cette contribution qu’en adoptant une telle architecture distribuée, la disponibilité de BGP sera augmentée considérablement versus une architecture monolithique. Dans la troisième contribution, on propose une méthode de partitionnement de la table de routage que nous avons appelé DRTP pour diviser la table de BGP sur plusieurs cartes de contrôle. Cette contribution vise à augmenter la scalabilité de la table de routage et la parallélisation de l’algorithme de recherche (Best Match Prefix) en partitionnant la table de routage sur plusieurs nœuds physiquement distribués.The increasing number of end users has led to an exponential growth in the Internet routing table. The routing table is expected to reach a size of one million prefixes within the coming few years. Besides, current core routers may easily attain hundreds of connected BGP peers simultaneously. In classical monolithic architecture, the BGP protocol runs as a single entity inside the router. This architecture suffers from two drawbacks: scalability and reliability. BGP scalability can be measured in terms of the number of connected peers that can be handled and the size of the routing table. On the other hand, the reliability is a critical issue in core routers. If the BGP instance inside the router fails, all peers’ connections will shutdown and the new reachability state will be propagated across the Internet in a non trivial convergence delay. Although, in current core routers, the resiliency is increased considerably, it’s mainly implemented via a primary-backup redundancy scheme which limits the BGP scalability. In this thesis we address the two mentioned BGP drawbacks by proposing a novel distributed approach to increase both scalability and reliability of BGP without changing the semantic of the protocol. The BGP distributed architecture in the first paper is built to satisfy both requirements: scalability and reliability by adequately exploiting parallelism and module separation. In our model, BGP functionalities are split in a master-slave manner and the RIB (Routing Information Base) is replicated to multiple controller cards, to form a cluster of parallel computing entities. In the second paper, we address the fault tolerance of BGP within the distributed architecture presented in the first paper. We prove analytically that, by adopting the distributed architecture of BGP the availability of BGP will be increased considerably versus a monolithic architecture. In the third paper we propose a distributed parallel scheme called DRTP to partition the BGP routing table on multiple controller cards. DRTP aims at increasing the BGP scalability and the parallelization of the Best Match Prefix algorithm

Energy-aware routing techniques for software-defined networks

Achieving energy efficiency has recently become a key topic of networking research due to the ever-increasing power consumption and CO2 emissions generated by large data networks. This problem is becoming even more concerning and challenging given the drastic traffic increase expected over the next few years. However, the use of efficient energy-aware strategies could overturn this situation reducing the electricity consumption of Internet data transmission networks, as well as contributing to mitigate the environmental impact of other sectors. The existence of redundant network elements with high capacities is a common design practice in current network infrastructures in order to face suddenly failures or peak traffic flows. However, these additional resources remain either unused or barely used most of the time leading to an undesired energy waste. Therefore, putting into sleep mode (i.e. a low-power state) unused elements is an effective and widely-accepted strategy to decrease the consumption of data networks. In this context, SDN can be seen as an attractive solution to achieve the long-awaited energy efficiency in current communications systems, since they allow a flexible programmability suitable for this problem. This doctoral thesis tackles the problem of optimizing the power consumption in SDN through the design of energy-aware routing techniques that minimize the number of network elements required to satisfy an incoming traffic load. Different from existing related works, we focus on optimizing energy consumption in SDN with in-band control traffic in order to close this important gap in the literature and provide solutions compatible with operational backbone networks. Complementing the general aim of improving the energy efficiency in SDN, this research is also intended to cover important related features such as network performance, QoS requirements and real-time operation. Accordingly, this study gives a general perspective about the use of energy efficient routing techniques, which cover integrated routing considerations for the data and control plane traffic in SDN. By using realistic input data, significant values of switched-off links and nodes are reached, which demonstrates the great opportunity for saving energy given by our proposals. The obtained results have also validated the intrinsic trade-off between environmental and performance concerns, considering several performance indicators. These findings confirm that energy-aware routing schemes should be designed considering specific traffic requirements and performance metric bounds. Moreover, it is shown that jointly considering QoS requirements and energy awareness is an effective approach to improve, not only the power consumption, but the performance on critical parameters such as control traffic delay and blocking rate. Similarly, the proposed dynamic traffic allocation with congestion-aware rerouting is able to handle demanding traffic arrival without degrading the performance of higher priority traffic. In general, our proposals are fine-grained, easy to implement and quite balanced and effective in their results looking for a suitable and readily deployment in real-world SDN scenarios. Therefore, the conducted research and contributions reported through this document not only add to what is known about the potential of energy-aware routing techniques, but also stand as a valuable solution on the road to a sustainable networking.L'assoliment de l'eficiència energètica s'ha convertit recentment en un tema clau de recerca de xarxes a causa dels creixents nivells de consum d'energia i emissions de CO2 generats per les xarxes de dades. Aquest problema es torna cada vegada més preocupant i desafiant, donat el dràstic augment del trànsit esperat en els propers anys. No obstant això, l'ús d'estratègies energètiques eficients podria invertir aquesta situació, reduint el consum d'electricitat de les xarxes de dades d'Internet i contribuint a mitigar l'impacte ambiental d'altres sectors. L'existència d'elements de xarxa redundants i amb grans capacitats és una pràctica de disseny habitual en les infraestructures de xarxes actuals per afrontar fallades sobtades o fluxos de trànsit més elevats. Tanmateix, aquests recursos addicionals romanen poc o gens utilitzats la major part del temps, generant un desaprofitament d'energia no desitjat. Per tant, posar en mode de repòs (és a dir, un estat de baixa potència) elements no utilitzats és una estratègia efectiva i àmpliament acceptada per disminuir el consum en xarxes de dades. En aquest context, les xarxes definides per programari (SDN) es poden considerar una solució atractiva per aconseguir l'esperada eficiència energètica en els sistemes de comunicacions actuals, ja que permeten una flexible programabilitat idònia per a aquest problema. Aquesta tesi doctoral aborda el problema d'optimitzar el consum d'energia en SDN a través del disseny de tècniques d'encaminament conscients de l'energia que minimitzen la quantitat d'elements de xarxa necessaris per satisfer una càrrega de trànsit entrant. Diferent dels treballs existents, aquesta tesi es centra a optimitzar el consum d'energia en SDN amb el control de tràfic dins de banda per tancar aquesta important bretxa en la literatura i proporcionar solucions compatibles amb xarxes troncals operatives. Complementant l'objectiu general de millorar l'eficiència energètica en SDN, aquesta recerca també pretén cobrir altres importants paràmetres relacionats, com ara el rendiment de la xarxa, els requisits de qualitat de servei (QoS) i el funcionament en temps real. En conseqüència, aquest estudi ofereix una perspectiva general sobre l'ús de tècniques d'encaminament eficients energèticament, que contempla consideracions integrades per al tràfic de dades i del pla de control en SDN. Prenent dades d'entrada realistes, es van aconseguir desconnectar significatives quantitats d'enllaços i nodes, la qual cosa demostra la gran oportunitat d'estalvi d'energia que ofereixen les nostres propostes. Els resultats obtinguts també validen el estret compromís entre les preocupacions ambientals i les qüestions de rendiment de la xarxa, considerant diversos indicadors de rendiment. Aquests resultats confirmen que els esquemes d'encaminament conscients de l'energia s'han de dissenyar tenint en compte els requisits de tràfic específics i els límits desitjats de les mètriques de rendiment. A més, es demostra que, considerant conjuntament els requisits de QoS i de l'energia necessària, és un enfocament eficaç per millorar, no només el consum d'energia, sinó també el rendiment en paràmetres crítics, com la latència del tràfic de control i la probabilitat de bloqueig. De manera semblant, l'assignació dinàmica de tràfic proposta, amb re-encaminament conscient de la congestió, permet gestionar grans volums de trànsit sense degradar el rendiment de les demandes de major prioritat. En general, les nostres propostes són precises, fàcils d'implementar i bastant equilibrades i efectives en els seus resultats, buscant un desplegament adequat i fàcil en escenaris pràctics de SDN. Per tant, la recerca realitzada i les contribucions contingudes en aquest document no només afegeixen el que es coneix sobre el potencial de les tècniques d'encaminament conscients de l'energia, sinó que també representen una valuosa solució en el camí cap a una xarxa sostenibl

Feasibility of wireless mesh for LTE-Advanced small cell access backhaul

Mobiilidatan määrä on muutaman viime vuoden aikana kasvanut voimakkaasti ja nykyiset ennustukset arvioivat eksponentiaalista kasvukäyrää tulevien vuosien aikana. Matkapuhelinjärjestelmät ovat kehittyneet nopeasti tämän trendin ohjaamana. Neljännen sukupolven matkapuhelinverkkostandardien myötä, uudet innovaatiot kuten heterogeeniset verkkoratkaisut tarjoavat ratkaisun nykyisiin skaalautuvuus- ja kapasiteettiongelmiin. Joitain ilmeisiä ongelmakohtiakin kuitenkin esiintyy kuten heterogeenisten verkkojen runkokytkennän toteuttaminen. Yksi lupaavimmista tavoista toteuttaa heterogeenisten verkkojen runkokytkentä on langaton ja itseorganisoituva mesh-verkko. Tämän opinnäytetyön tavoitteena on varmistaa ja testata Nokia Siemens Networksin kehittämän mesh-runkokytkentäverkkokonseptin toteutettavuutta ja toiminnallisuutta soveltuvan validointijärjestelmän avulla. Kaiken kaikkiaan validointijärjestelmä ja sen päälle toteutettu mesh-protokolla toimivat moitteettomasti koko kehitys- ja testausprosessin ajan. Konseptin eri ominaisuudet ja mekanismit todistettiin täysin toteutettaviksi ja toimiviksi. Muutamalla lisäominaisuudella ja konseptiparannuksella mesh-konsepti tarjoaa houkuttelevan ja innovatiivisen ratkaisun heterogeenisten verkkojen runkokytkentään tulevaisuudessa.Mobile traffic demands and volumes are increasing and will dramatically keep increasing in the future. Along with this, mobile networks have evolved to better match this growth. Fourth generation cellular network standard introduced a set of new innovations for mobile communications, including support for heterogeneous network deployments. Heterogeneous networking is the likely answer for future mobile data capacity shortage but also poses some challenges, the most evident being how to implement the backhauling. One of the most promising heterogeneous network backhaul solutions is a meshed radio system with self-organizing features. The main scope of this master's thesis is the verification of functionality and feasibility of a wireless mesh backhaul concept developed by Nokia Siemens Networks through a proof-of-concept system. All in all, the wireless mesh proof-of-concept system performed strongly throughout the development and testing process. The different functionalities were proven to work successfully together. With further development and enhancement, the system concept displays extreme potential for a state-of-the-art heterogeneous network backhaul technology