Clock Distribution Networks play a vital role in performance and reliability of a system. However, temperature gradients observed in 3D ICs hamper the functionality of CDNs in terms of varying skew and propagation delay. This thesis presents two compensation techniques, Adaptive Voltage and Controllable Delay, to overcome these problems. The compensation methods are validated using a FPGA-based test vehicle. Modification in traditional buffer design are also presented and the performance as well as the area and power overhead of both the implementations is compared.

Content Distribution Networks have existed for some years. They involve the following problem domains and have attracted attention both in academic research and industry: content replica placement, content location and routing, swarm intelligence, and overlay network self-organization for this type of distributed system. In this project, we propose a novel Content Distribution Network architecture – PlentyCast. This study focuses on improving access latency, network scalability, high content availability, low bandwidth consumption, and improving infrastructure performance for Content Distribution Networks. Outstanding problems such as: Flash crowd, DoS, and difficulty of traffic engineering due to Peer-to-Peer are addressed. / Mediadistributionsnätverk har funnits några år. De har fått uppmärksamhet i både akademisk forskning och i industrin och kännetecknas av följande frågor: placering av innehållskopior, lokalisering av innehåll och routing, svärm intelligens, överlagrade nätverks självorganisering för denna typ av fördelade system. I denna rapport studeras en ny nätverksarkitektur för innehållsfördelning - PlentyCast. Denna studie fokuserar på tillgångslatens, nätverksskalbarhet, hög innehållstillgång, låg bandbreddskonsumtion, och förbättrad infrastrukturprestanda för Innehållsfördelningsnätverk.

Les réseaux orientés contenus (CCN) ont été créés afin d'optimiser les ressources réseau et assurer une plus grande sécurité. Le design et l'implémentation de cette architecture est encore à ces débuts. Ce travail de thèse présente des propositions pour la gestion de trafic dans les réseaux du future.Il est nécessaire d'ajouter des mécanismes de contrôle concernant le partage de la bande passante entre flots. Le contrôle de trafic est nécessaire pour assurer un temps de latence faible pour les flux de streaming vidéo ou audio, et pour partager équitablement la bande passante entre flux élastiques. Nous proposons un mécanisme d'Interest Discard pour les réseaux CCN afin d?optimiser l'utilisation de la bande passante. Les CCN favorisant l'utilisation de plusieurs sources pour télécharger un contenu, nous étudions les performances des Multipaths/ Multisources; on remarque alors que leurs performances dépendent des performances de caches.Dans la deuxième partie de cette thèse, nous évaluons les performances de caches en utilisant une approximation simple et précise pour les caches LRU. Les performances des caches dépendent fortement de la popularité des objets et de la taille des catalogues. Ainsi, Nous avons évalué les performances des caches en utilisant des popularités et des catalogues représentant les données réelles échangées sur Internet. Aussi, nous avons observé que les tailles de caches doivent être très grandes pour assurer une réduction significative de la bande passante; ce qui pourrait être contraignant pour l'implémentation des caches dans les routeurs.Nous pensons que la distribution des caches devrait répondre à un compromis bande passante/mémoire; la distribution adoptée devrait réaliser un coût minimum. Pour ce faire, nous évaluons les différences de coût entre architectures. / Content Centric Network (CCN) architecture has been designed to optimize network resources and ensure greater security. The design and the implementation of this architecture are only in its beginning. This work has made some proposals in traffic management related to the internet of the future.We argue that it is necessary to supplement CCN with mechanisms enabling controlled sharing of network bandwidth by competitive flows. Traffic control is necessary to ensure low latency for conversational and streaming flows, and to realize satisfactory bandwidth sharing between elastic flows. These objectives can be realized using "per-flow bandwidth sharing". As the bandwidth sharing algorithms in the IP architecture are not completely satisfactory, we proposed the Interest Discard as a new technique for CCN. We tested some of the mechanisms using CCNx prototype software and simulations. In evaluating the performance of multi-paths we noted the role of cache performance in the choice of selected paths.In the second part, we evaluate the performance of caches using a simple approximation for LRU cache performance that proves highly accurate. As caches performance heavily depends on populations and catalogs sizes, we evaluate their performance using popularity and catalogs representing the current Internet exchanges. Considering alpha values, we observe that the cache size should be very large, which can be restrictive for caches implementation in routers.We believe that the distribution of caches on an architecture creates an excessive bandwidth consumption. Then, it is important to determine a tradeoff bandwidth/memory to determine how we should size caches and where we should place them, this amounts to evaluate differences, in cost, between architectures

Dans cette thèse, on présente nos travaux sur la virtualisation dans le contexte de la réplication des serveurs de contenu vidéo. Les travaux couvrent la conception d’une architecture de virtualisation pour laquelle on présente aussi plusieurs algorithmes qui peuvent réduire les couts globaux à long terme et améliorer la performance du système. Le travail est divisé en plusieurs parties : les solutions optimales, les solutions heuristiques pour des raisons de passage à l’échelle, l’orchestration des services, l’optimisation multi-objective, la planification de services dans des réseaux actifs et complexes et l'intégration d'algorithmes dans une plate-forme réelle / In this thesis, we designed and implemented a tool which performs optimizations that reduce the number of migrations necessary for a delivery task. We present our work on virtualization in the context of replication of video content servers. The work covers the design of a virtualization architecture for which there are also several algorithms that can reduce overall costs and improve system performance. The thesis is divided into several parts: optimal solutions, greedy (heuristic) solutions for reasons of scalability, orchestration of services, multi-objective optimization, service planning in complex active networks, and integration of algorithms in real platform. This thesis is supported by models, implementations and simulations which provide results that showcase our work, quantify the importance of evaluating optimization techniques and analyze the trade-off between reducing operator cost and enhancing end user satisfaction index

L’objectif de cette thèse est de présenter de nouveaux algorithmes de répartition des ressources sous la forme de machines virtuelles (VMs) et fonction de réseau virtuel (VNFs) dans les Clouds et réseaux de diffusion de contenu (CDNs). La thèse comprend deux principales parties: la première se concentre sur la rentabilité des Clouds distribués, et développe ensuite les raisons d’optimiser les coûts ainsi que les émissions de carbone. Cette partie comprend quatre contributions. La première contribution est une étude de l’état de l’art sur la répartition des coûts et des émissions de carbone dans les environnements de clouds distribués. La deuxième contribution propose une méthode d’allocation des ressources, appelée NACER, pour les clouds distribués. La troisième contribution présente une méthode de placement VM efficace en termes de coûts et de carbone (appelée CACEV) pour les clouds distribués verts. Pour obtenir une meilleure performance, la quatrième contribution propose une méthode dynamique de placement VM (D-CACEV) pour les clouds distribués. La deuxième partie propose des algorithmes de placement de VNFs dans les Clouds et réseaux de CDNs pour optimiser les coûts. Cette partie comprend cinq contributions. Une étude de l’état de l’art sur les solutions proposées est le but de la première contribition. La deuxième contribution propose une méthode d’allocation des ressources, appelée CCVP, pour le provisionnement de service réseau dans les clouds et réseaux de ISP. La troisième contribution implémente le résultat de l’algorithme CCVP dans une plateforme réelle. La quatrième contribution considère l’effet de la permutation de VNFs dans les chaîne de services et la cinquième contribution explique le placement de VNFs pour les services à valeur ajoutée dans les CDNs / High energy costs and carbon emissions are two significant problems in distributed computing domain, such as distributed clouds and Content Delivery Networks (CDNs). Resource allocation methods (e.g., in form of Virtual Machine (VM) or Virtual Network Function (VNF) placement algorithms) have a direct effect on cost, carbon emission and Quality of Service (QoS). This thesis includes three related parts. First, it targets the problem of resource allocation (i.e., in the form of network aware VM placement algorithms) for distributed clouds and proposes cost and carbon emission efficient resource allocation algorithms for green distributed clouds. Due to the similarity of the network-aware VM placement problem in distributed clouds with a VNF placement problem, the second part of the thesis, getting experience from the first part, proposes a new cost efficient resource allocation algorithm (i.e., VNF placement) for network service provision in data centers and Internet Service Provider (ISP) network. Finally, the last part of the thesis presents new cost efficient resource allocation algorithms (i.e., VNF placement) for value-added service provisioning in NFV-based CDNs

<p dir="ltr">Privacy serves as a crucial safeguard for personal autonomy and information, enabling control over personal data and space, fostering trust and security in society, and standing as a cornerstone of democracy by protecting against unwarranted interference. This work aims to enhance Tor, a volunteer-operated network providing privacy to over two million users, by improving its programmability, security, and user-friendliness to support wider adoption and underscore the importance of privacy in protecting individual rights in the digital age.</p><p dir="ltr">Addressing Tor's limitations in adapting to new services and threats, this thesis introduces programmable middleboxes, enabling users to execute complex functions on Tor routers to enhance anonymity, security, and performance. This architecture, called Bento, is designed to secure middleboxes from harmful functions and vice versa, making Tor more flexible and efficient.</p><p dir="ltr">Many of the attacks on Tor's anonymity occur when an adversary can intercept a user’s traffic; it is thus useful to limit how much of a user's traffic can enter potentially adversarial networks. We tackle the vulnerabilities of onion services to surveillance and censorship by proposing DeTor_OS, a Bento function enabling geographic avoidance for onion services- which is challenging since no one entity knows the full circuit between user and onion service, providing a method to circumvent adversarial regions and enhance user privacy.</p><p dir="ltr">The final part focuses on improving onion services' usability and security. Despite their importance, these services face high latency, Denial of Service (DoS) and deanonymization attacks due to their content. We introduce CenTor, a Content Delivery Network (CDN) for onion services using Bento, offering replication, load balancing, and content proximity benefits. Additionally, we enhance performance with multipath routing strategies through uTor, balancing performance and anonymity. We quantitatively analyze how geographical-awareness for an onion service CDN and its clients could impact a user’s anonymity- performance versus security tradeoff. Further, we evaluate CenTor on the live Tor network as well as large-scale Shadow simulations.</p><p dir="ltr">These contributions, requiring no changes to the Tor protocol, represent significant advancements in Tor's capabilities, performance, and defenses, demonstrating potential for immediate benefits to the Tor community.</p>

Les changements économiques des dernières décennies telles que la mondialisation et la libéralisation des marchés ont modifié la structure des entreprises et les flux d’échanges, et ce en affectant l’organisation du territoire. Les services gouvernementaux, appuyés des organismes communautaires, ont réagi en développant diverses stratégies à l’échelle locale. Ainsi, ils répondent à une variété de besoins socioéconomiques et s'adaptent aux changements dans les quartiers montréalais. Sur le plan économique, diverses organisations favorisent l'entrepreneuriat local par diverses actions et stratégies. Cette recherche s'intéresse au rôle et aux effets des organismes communautaires dans le développement et la consolidation de petites entreprises via leur rôle sur la viabilité et la vitalité des entreprises dans l’un des arrondissements les plus hétérogènes de Montréal. Spécifiquement, elle s’intéresse à l’effet de ces actions sur le développement entrepreneuriale locale dans l’arrondissement de Côte-des-Neiges/ Notre-Dame-de-Grâce à cause de son caractère hétérogène sur le plan ethnique, sur le plan socio-économique et de ses particularités géographiques. Les résultats obtenus indiquent que la viabilité des entreprises est à la base de la majorité des actions et stratégies déployés par les organismes de soutien. Pour ce qui est de l’enracinement des entreprises, il y a beaucoup d’externalités liées au marché qui influencent les décisions du lieu d’établissement et de relocalisation et qui sont hors de portée des actions des organisations. Globalement, nous pouvons dire que Montréal est une ville résiliente. En effet, l’organisation du milieu communautaire permet, malgré quelques lacunes dans les stratégies de promotions et de répartitions des tâches, un soutien adéquat aux entrepreneurs. Du travail reste à faire afin de valoriser l’entrepreneuriat comme métier auprès de la population et encourager les universitaires à auto-entreprendre. / The economic changes of the last decades such as globalization and liberalization of markets has changed the business structure and trade flows, thus affecting the organization of the territory. Community organizations, complementary with government services, have responded and are responding with various strategies, including those acting locally. They are responding to a variety of socio-economic needs and are adapting to changes in neighbourhoods. On the economic front, various organizations promote local entrepreneurship through various actions and strategies. This research examines the role and impact of community organizations in the development and consolidation of small businesses. How do the organizations impact on the vitality and viability of businesses in one of the most heterogenic boroughs of Montreal. We are also interested in their strategies and actions to improve the viability and business roots in the community, specifically on the impact of these actions on the local entrepreneurial development in Cote-des-Neiges / Notre-Dame-de-Grâce because of its heterogeneity in terms of ethnicity, socio-economic and its geographical features. The results obtained indicate that the majority of actions and strategies undertaken by organizations refer to enterprise viability. In terms of firmly establishing companies, there are many externalities that influence the entrepreneur’s decisions on the establishment and relocation of enterprises which are beyond the actions of local organizations. Overall, we can qualify Montreal as a resilient city. Indeed, the organization of the community services permits, despite some shortcomings in the strategies for promotion and distribution of tasks, an adequate support to entrepreneurs. Work remains to be done on promoting entrepreneurship as an occupation among the population and encourage academics to work in this field.

Les changements économiques des dernières décennies telles que la mondialisation et la libéralisation des marchés ont modifié la structure des entreprises et les flux d’échanges, et ce en affectant l’organisation du territoire. Les services gouvernementaux, appuyés des organismes communautaires, ont réagi en développant diverses stratégies à l’échelle locale. Ainsi, ils répondent à une variété de besoins socioéconomiques et s'adaptent aux changements dans les quartiers montréalais. Sur le plan économique, diverses organisations favorisent l'entrepreneuriat local par diverses actions et stratégies. Cette recherche s'intéresse au rôle et aux effets des organismes communautaires dans le développement et la consolidation de petites entreprises via leur rôle sur la viabilité et la vitalité des entreprises dans l’un des arrondissements les plus hétérogènes de Montréal. Spécifiquement, elle s’intéresse à l’effet de ces actions sur le développement entrepreneuriale locale dans l’arrondissement de Côte-des-Neiges/ Notre-Dame-de-Grâce à cause de son caractère hétérogène sur le plan ethnique, sur le plan socio-économique et de ses particularités géographiques. Les résultats obtenus indiquent que la viabilité des entreprises est à la base de la majorité des actions et stratégies déployés par les organismes de soutien. Pour ce qui est de l’enracinement des entreprises, il y a beaucoup d’externalités liées au marché qui influencent les décisions du lieu d’établissement et de relocalisation et qui sont hors de portée des actions des organisations. Globalement, nous pouvons dire que Montréal est une ville résiliente. En effet, l’organisation du milieu communautaire permet, malgré quelques lacunes dans les stratégies de promotions et de répartitions des tâches, un soutien adéquat aux entrepreneurs. Du travail reste à faire afin de valoriser l’entrepreneuriat comme métier auprès de la population et encourager les universitaires à auto-entreprendre. / The economic changes of the last decades such as globalization and liberalization of markets has changed the business structure and trade flows, thus affecting the organization of the territory. Community organizations, complementary with government services, have responded and are responding with various strategies, including those acting locally. They are responding to a variety of socio-economic needs and are adapting to changes in neighbourhoods. On the economic front, various organizations promote local entrepreneurship through various actions and strategies. This research examines the role and impact of community organizations in the development and consolidation of small businesses. How do the organizations impact on the vitality and viability of businesses in one of the most heterogenic boroughs of Montreal. We are also interested in their strategies and actions to improve the viability and business roots in the community, specifically on the impact of these actions on the local entrepreneurial development in Cote-des-Neiges / Notre-Dame-de-Grâce because of its heterogeneity in terms of ethnicity, socio-economic and its geographical features. The results obtained indicate that the majority of actions and strategies undertaken by organizations refer to enterprise viability. In terms of firmly establishing companies, there are many externalities that influence the entrepreneur’s decisions on the establishment and relocation of enterprises which are beyond the actions of local organizations. Overall, we can qualify Montreal as a resilient city. Indeed, the organization of the community services permits, despite some shortcomings in the strategies for promotion and distribution of tasks, an adequate support to entrepreneurs. Work remains to be done on promoting entrepreneurship as an occupation among the population and encourage academics to work in this field.

Video streaming is widely recognized as the next Internet killer application. It was not one of the Internet's original target applications and its protocols (TCP in particular) were tuned mainly for e efficient bulk file transfer. As a result, a significant effort has focused on the development of UDP-based special protocols for streaming multimedia on the Internet. Recently, there has been a shift in video streaming from UDP to TCP, and specifically to HTTP. HTTP streaming provides a very attractive platform for video distribution on the Internet mainly because it can utilize all the current Internet infrastructure. In this thesis we make the argument that the marriage between HTTP streaming and the current Internet infrastructure can create many problems and inefficiencies. In order to solve these issues, we provide a set of techniques and protocols that can help both the network and end-hosts to make better decisions to improve video streaming quality. The thesis makes the following contributions: - We conduct a characterization study of popular commercial streaming services on mobile platforms. Our study shows that streaming services make different design decisions when implementing video players on different mobile platforms. We show that this can lead to several inefficiencies and undesirable behaviors specially when several clients compete for bandwidth in a shared bottleneck link. - Fairness between traffic flows has been preserved on the Internet through the use of TCP. However, due to the dynamics of adaptive video players and the lack of standard client adaptation techniques, fairness between multiple competing video flows is still an open issue of research. Our work extends the definition of standard bitrate fairness to utility fairness where utility is the Quality of Experience (QoE) of a video stream. We define QoE max-min fairness for a set of adaptive video flows competing for bandwidth in a network and we develop an algorithm that computes the set of bitrates that should be assigned to each stream to achieve fairness. We design and implement a system that can apply QoE fairness in home networks and evaluate the system on a real home router. - A well known problem that has been associated with TCP traffic is the buffer bloat problem. We use an experimental setup to show that adaptive video flows can cause buffer bloat which can significantly harm time sensitive applications sharing the same bottleneck link with video traffic. In addition, we develop a technique that can be used by video players to mitigate this problem. We implement our technique in a real video player and evaluate it on our testbed. - With the increasing popularity of video streaming on the Internet, the amounts of traffic on the peering links between video streaming providers and Internet Service Providers (ISPs) have become the source of many disputes. Hybrid CDN/P2P streaming systems can be used to reduce the amounts of traffic on the peering links by leveraging users upload bandwidth to redistribute some of the load to other peers. We develop an analysis for hybrid CDN/P2P systems that broadcast live adaptive video streams. The analysis helps the CDN to make better decisions to optimize video quality for its users.

Denna studie undersöker hur svenska myndigheter bör tänka för att uppnå en stabil driftlösning vid distribuering av webbaserad krisinformation med hjälp av molntjänster. Resultatet är fyra faktorer som myndigheter kan använda sig av och ta hänsyn till för att uppnå detta. Resultatet uppnås genom intervjuer med yrkesverksamma personer inom området, både från myndigheter och privata företag, för bringa flera perspektiv på forskningsfrågan. Faktorerna härleds därefter från intervjuerna med en induktiv ansats för att sedan testas med en deduktiv ansats mot tidigare forskning som lyfter upp tio utmaningar vid införande av molntjänster hos myndigheter. För att bekräfta sin relevans och funktion testas sedan faktorerna i en historisk fallstudie av ett fall där ett falskt VMA-larm utlösts i Stockholm sommaren 2017. / This study examines what Swedish authorities should consider in order to achieve a stable operational solution when distributing web-based crisis information using Cloud Computing. The study results in four factors that authorities can use and take into account in order to achieve this. The result is achieved through interviews with professionals, both from private and public sectors, to bring multiple perspectives on the topic. The factors derive from the interviews with an inductive approach and then tested with a deductive approach to a previous research that highlights ten major challenges facing governments in implementing Cloud Computing. To confirm their relevance and function, the factors are then tested in a historical case study of a case where a false important notice to the public (VMA) was sent in Stockholm in the summer of 2017.