Content delivery networks (CDNs) depend on distributed cache servers to reduce the content delivery distance and latency to end users. Nevertheless, a CDN's cache footprint is greatly limited by the high cost in deploying and maintaining large- scale cache servers. To break the limit, CDN providers adopt a new content caching strategy that allows end users to share their storage/bandwidth resources with each other. Two core questions need to answer in this CDN strategy: (1) how to incentivize end users to contribute their resources? and (2) how to facilitate transparent, secure content exchange among end users? We propose a new CDN solution, called SmartSharing, where users contribute their Over-the-top (OTT) devices as mini cache servers. With SmartSharing, an OTT device can share the content the OTT owner is downloading and in addition can cache content for neighboring OTT devices in the same area. To incentivize end users to contribute their resources, SmartSharing uses game theory and the Expectation- Maximization (EM) algorithm to determine content delivery schedule and the pricing scheme. To facilitate content trading among end users, SmartSharing uses smart contracts in Ethereum to create a transparent and safe transaction platform. We evaluate SmartSharing with real-world trace driven simulation as well as smart con- tract prototype in Ethereum using content meta-data and the derived pricing scheme. By disclosing the internal dynamics in content delivery schedule and pricing scheme and analyzing the overhead in content trading, we show that SmartSharing is an effective new CDN solution that benefi ts content providers, CDN, and end users. / Graduate

Internet-scale dissemination of streaming contents (e.g. live sport games) is most successfully being provided by Multicast Content Delivery Networks (Multicast CDN). Multicast CDN is composed of dedicated servers placed strategically over the Internet, which forward content from origin site to end users. Multicast CDN delivers huge amount of data traffic, and therefore its major operational cost is the ISP cost for network access. Existing Multicast CDNs route user requests to most suitable server based on application performance, such as network delay, server throughput, Internet path congestion etc., without taking into account the potentially high ISP cost it may incur. Multicast CDNs need to control their ISP cost to remain commercially competitive since ISP cost is the most indicative factor affecting the pricing of their services. In this work, we present novel Multicast CDN Request Routing algorithms that minimize ISP cost while still maintaining good network performance for users. Multicast CDN Request Routing algorithms control majority of traffic assigned to servers and therefore directly impacts the ISP cost. ISP cost and user network performances are orthogonal metrics of performance and in order to balance the trade-off between them we introduce overall delay as a constraint to the Multicast CDN Request Routing algorithm. Multicast CDNs are business customers of ISPs and therefore can independently choose to reduce their bills by considering the ways in which ISPs charge. We have designed Request Routing algorithms that exploit the economy of scale in ISP charging function in assigning users to servers. We have developed Request Routing algorithms that exploit the nature of Percentile-based charging used by ISPs to compute the charging volume for traffic generated at server sites. Multicast CDN can cooperate with ISPs to reduce the operational cost of both the parties. Multicast CDN controls how traffic is redirected on the overlay, and that can conflict with how underlying ISPs want the traffic to be forwarded. We have developed Request Routing algorithms that assign users to servers that are available over cheaper IP routes. This reduces the transmission costs for ISPs and these savings can be transferred onto Multicast CDN.

Significant portion of today’s internet traffic emerge from multimedia services. When coupled with growth in number of users accessing these services, there is tremendous increase in network traffic. CDNs aid in handling this traffic and offer reliable services by distributing content across different locations. The concept of virtualization transformed traditional data centers into flexible cloud infrastructure. With the advent of cloud computing technology, multimedia providers have scope for establishing CDN using network operator’s cloud environment. However, the main challenge while establishing such CDN is implementing a cost efficient and dynamic mechanism which guarantees good service quality to users. This thesis aims to develop, implement and assess the performance of a model that coordinates deployment of virtual servers in the cloud. A solution which dynamically spawns and releases virtual servers according to variations in user demand has been proposed. Cost-based heuristic algorithm is presented for deciding the placement of virtual servers in OpenStack based federated clouds. Further, the proposed model is implemented on XIFI cloud and its performance is measured. Results of the performance study indicate that virtual CDNs offer reliable and prompt services. With virtual CDNs, multimedia providers can regulate expenses and have greater level of flexibility for customizing the virtual servers deployed at different locations.

The Cloud infrastructure has become an ideal platform for large-scale applications, such as Video-on-Demand (VoD). As VoD systems migrate to the Cloud, new challenges emerge. The complexity of the Cloud system due to virtualization and resource sharing complicates the Quality of Experience (QoE) management. Operational failures in the Cloud can lead to session crashes. In addition to the Cloud, there are many other systems involved in the large-scale video streaming. These systems include the Content Delivery Networks (CDNs), multiple transit networks, access networks, and user devices. Anomalies in any of these systems can affect users’ Quality of Experience (QoE). Identifying the anomalous system that causes QoE degradation is challenging for VoD providers due to their limited visibility over these systems. We propose to apply end user QoE in the management and control of large-scale VoD systems in the Cloud. We present a QoE-based management and control systems and validate them in production Clouds. QMan, a QoE based Management system for VoD in the Cloud, controls the server selection adaptively based on user QoE. QWatch, a scalable monitoring system, detects and locates anomalies based on the end-user QoE. QRank, a scalable anomaly identification system, identifies the anomalous systems causing QoE anomalies. The proposed systems are developed and evaluated in production Clouds (Microsoft Azure, Google Cloud and Amazon Web Service). QMan provides 30% more users with QoE above the “good” Mean Opinion Score (MOS) than existing server selection systems. QMan discovers operational failures by QoE based server monitoring and prevents streaming session crashes. QWatch effectively detects and locates QoE anomalies in our extensive experiments in production Clouds. We find numerous false positives and false negatives when system metric based anomaly detection methods are used. QRank identifies anomalous systems causing 99.98% of all QoE anomalies among transit networks, access networks and user devices. Our extensive experiments in production Clouds show that transit networks are the most common bottleneck causing QoE anomalies. Cloud provider should identify bottleneck transit networks and determine appropriate peering with Internet Service Providers (ISPs) to bypass these bottlenecks.

This work deals with algorithms for distributing and mapping content on nodes in CDN system. Compares local and global algorithms for loading files on origin and edge servers. A high level CDN simulator is made. A matrix based approach for mapping content on CDN servers is proposed along with tranformation for solution of mapping optimalisation through genetic algorithms.

Les services de distribution de contenus évoluent rapidement. Un axe majeur d’évolution concerne la fédération de distributeurs de contenus distincts mettant ensemble leurs ressources respectives et agissant en tant qu’entité unique par rapport aux fournisseurs de contenus (Content Providers). En particulier, nous proposons une solution technique basée sur une architecture centralisée qui permet de prendre des décisions statiques d’établissement et de provisionnement de fédérations ainsi que des décisions de contrôle dynamique de fédérations établies. Nous adressons les aspects statiques de prise de décision en introduisant un modèle d’optimisation que nous appliquons à différents scénarios de fédération d’intérêt pour le marché. Nous démontrons que, quand la demande sur le marché de distribution de contenu est élevée, les distributeurs de contenus ont intérêt, d’un point de vue économique, à fédérer. Dans le contexte de contrôle dynamique de fédérations, nous nous focalisons sur le contrôle d’événements de pointe (peak events) dans une fédération de distributeurs de contenus. Différentes approches de contrôle sont valables à ce niveau. Nous effectuons des simulations basées sur des traces de trafic réelles dans le but de comparer les différentes approches. Nous démontrons que, quand une approche jointe de contrôle d’événements de pointe est adoptée au sein d’une fédération, la fédération réagit mieux à ces événements. Ceci se traduit en un moindre volume de sessions rejetées et en une meilleure résolution vidéo ressentie par les internautes. Notre travail sur la fédération nous conduit à se focaliser sur le rôle d’un Telco dans un contexte fédéré. / Content Distribution Services are evolving fast in various directions. One of them is the federation of CDNs, referring to a number of CDN providers putting together their assets and acting as a single entity with regards to content providers. We introduce a technical solution based on a centralized architecture that allows taking static decisions of federation establishment and provisioning and dynamic decisions of federation control. Static decision-making is enabled through an optimization model that we apply to concrete use cases of federation. We demonstrate that, in case of high market demand, CDN providers always have an interest in federating. In particular, some CDN providers can double their economic gains through federating. In the context of federation dynamic control, we focus on the control of peak events within a federation of CDNs and we introduce different control frameworks at this level. We conduct trace-driven simulations in order to assess different frameworks. We demonstrate that, when a joint approach for events control is adopted within a federation of CDNs, the federation is better resilient to peak events. This translates into a higher hit ratio of the federation and a better video resolution witnessed by end users. Our work on CDN federation leads us to focus on the role of a Telco in this context. In particular, we identify three added-value services that can be proposed by a Telco to a federation of CDNs or to individual Over the Tops (OTTs).We suggest enhancements of the Telco control infrastructure and new Telco APIs in order to enable the proposed services.

Outsourcing data services to the cloud is a nature fit for cloud usage. However, increasing security and privacy concerns from both enterprises and individuals on their outsourced data inhibit this trend. In this dissertation, we introduce service-centric solutions to address two types of security threats existing in the current cloud environments: semi-honest cloud providers and malicious cloud customers. Our solution aims not only to provide confidentiality and access controllability of outsourced data with strong cryptographic guarantee, but, more importantly, to fulfill specific security requirements from different cloud services with effective systematic ways. To provide strong cryptographic guarantee to outsourced data, we study the generic security problem caused by semi-honest cloud providers and introduce a novel proxy-based secure data outsourcing scheme. Specifically, our scheme improves the efficiency of traditional proxy re-encryption algorithm by integrating symmetric encryption and proxy re-encryption algorithms. With less computation cost on applying re-encryption operation directly on the encrypted data, our scheme allows flexible and efficient user revocation without revealing underlying data and heavy computation in the untrusted cloud. To address specific requirement from different cloud services, we investigate two specific cloud services: cloud-based content delivery service and cloud-based data processing service. For the former one, we focus on preserving cache property in the content delivery network and propose CloudSeal, a scheme for securely and flexibly sharing and distributing content via the public cloud. With the ability of caching the major part of a stored cipher content object in the delivery network for content distribution and keeping the minor part with the data owner for content authorization, CloudSeal achieves security and efficiency both theoretically and experimentally. For the later service, we design and realize CloudSafe, a framework that supports secure and efficient data processing with minimum key leakage in the vulnerable cloud virtualization environment. Through the adoption of one-time cryptographic key strategy and a centralized key management framework, CloudSafe efficiently avoids cross-VM side channel attack from malicious cloud customers in the cloud. Our experimental results confirm the practicality and scalability of CloudSafe. / Ph. D.

URL parser and normalization processes are common and important operations in different web frameworks and technologies. In recent years, security researchers have targeted these processes and discovered high impact vulnerabilities and exploitation techniques. In a different approach, we will focus on semantic disconnect among different framework-independent web technologies (e.g., browsers, proxies, cache servers, web servers) which results in different URL interpretations. We coined the term “Path Confusion” to represent this disagreement and this thesis will focus on analyzing enabling factors and security impact of this problem.In this thesis, we will show the impact and importance of path confusion in two attack classes including Style Injection by Relative Path Overwrite (RPO) and Web Cache Deception (WCD). We will focus on these attacks as case studies to demonstrate how utilizing path confusion techniques makes targeted sites exploitable. Moreover, we propose novel variations of each attack which would expand the number of vulnerable sites and introduce new attack scenarios. We will present instances which have been secured against these attacks, while being still exploitable with introduced Path Confusion techniques. To further elucidate the seriousness of path confusion, we will also present the large scale analysis results of RPO and WCD attacks on high profile sites. We present repeatable methodologies and automated path confusion crawlers which detect thousands of sites that are still vulnerable to RPO or WCD only with specific types of path confusion techniques. Our results attest the severity of path confusion based class of attacks and how extensively they could hit the clients or systems. We analyze some browser-based mitigation techniques for RPO and discuss that WCD cannot be dealt as a common vulnerability of each component; instead it arises when an ecosystem of individually impeccable components ends up in a faulty situation.

Fault tolerance is essential in a production-grade service delivery network. One of the solution is build a clustered environment to keep system failure to a minimum. This thesis examines the use of high availability and load balancing services using open source tools in GNU/Linux. The thesis discusses some general technologies of high availability computing as virtualization, synchronization and mirroring. To build relatively cheap high availability clusters is suitable DRDB tool. DRDB is tool for build synchronized Linux block devices. This paper also examines Linux-HA project, Redhat Cluster Suite, LVS, etc. Content Delivery Networks (CDN) replicate content over several mirrored web servers strategically placed at various locations in order to deal with the flash crowds. A CDN has some combination a request-routing and replication mechanism. Thus CDNs offer fast and reliable applications and services by distributing content to cache servers located close to end-users. This work examines open-source CDNs Globule and CoralCDN and test performance of this CDNs in global deployment.

Un content delivery network (CDN), ou réseau de diffusion de contenu, Sont considérés comme la solution potentielle pour délivrer le volume de contenu croissant. Bien que les solutions CDN soient progressivement intégrées à l'infrastructure réseau, elles montrent toujours des limites technologiques pour faire face au nombre croissant d'applications exigeantes et gourmande en bande passante. Dans cette thèse, la principale cible de nos contributions est le routage des requêtes, qui est un mécanisme de livraison de contenu qui a un impact clé sur l'échelle et la performance du CDN, ainsi que sur la qualité de l'expérience perçue par l'utilisateur.Nous présentons tout d'abord un schéma flexible et un algorithme d'optimisation, basé sur la théorie de Lyapunov, pour le routage des requêtes dans les CDN. Notre approche en ligne fournit une qualité de service stable aux clients, tout en améliorant les délais de livraison de contenu. Elle réduit également les coûts de transport des données pour les opérateurs et surpasse les techniques existantes en termes de gestion du trafic de pointe.Deuxièmement, pour surmonter les limites du mécanisme de redirection utilisé dans les solutions de routage de demandes, nous introduisons une nouvelle approche de diffusion de contenu intégrant des principes de réseau centré sur l'information ou Information-centric networking (ICN) sans nécessiter de changement dans le réseau sous-jacent. Cette solution améliore les performances de diffusion de contenu et permet la mise en œuvre de stratégies de routage de demandes rentables. / Today, many devices are capable to capture full HD videos and use their network connections to access the Internet. The popularization of these devices and continuous efforts to increase network quality has brought a proper environment for the rise of live streaming. Associated with the large scale of Users Generated Content (UGC), live streaming presents new challenges. Content Delivery Networks (CDN)are considered as the potential solution to deliver this rising content volume. Although CDN solutions are progressively integrated with the network infrastructure, they still show technological limitations in dealing with the increasing amount of bandwidth-hungry and demanding applications. In this thesis, the main target of our contributions is request routing, which is a content delivery mechanism that has a key impact on scale and performance of the CDN, as well as on the perceived Quality of Experience (QoE). First, we present a flexible scheme and an optimization algorithm, based on Lyapunov theory, for request routing in CDNs. Our online approach provides a stable quality of service to clients, while improving content delivery delays. It also reduces data transport costs for operators and outperforms existing techniques in terms of peak traffic management.Second, to overcome the limitations of the redirection mechanism used in current request routing solutions, we introduce a new approach to content delivery incorporating Information-Centric Networking (ICN) principles without requiring any change in the underlying network. This solution improves content delivery performance and enables the implementation of cost efficient request routing strategies.