Distributed Dynamic Replica Placement and Request Redirection in Content Delivery Networks

Chiara Petrioli, Giancarlo Bongiovanni, Francesco Lo Prest

Content Delivery System for Optimal VoD Streaming

The demand of video contents has rapidly increased in the past years as a result of the wide deployment of IPTV and the variety of services offered by the network operators. One of the services that has especially become attractive to the customers is real-time video on demand (VoD) because it offers an immediate streaming of a large variety of video contents. The price that the operators have to pay for this convenience is the increased traffic in the networks, which are becoming more congested due to the higher demand for VoD contents and the increased quality of the videos. As a solution, in this paper we propose a hierarchical network system for VoD content delivery in managed networks, which implements redistribution algorithm and a redirection strategy for optimal content distribution within the network core and optimal streaming to the clients. The system monitors the state of the network and the behavior of the users to estimate the demand for the content items and to take the right decision on the appropriate number of replicas and their best positions in the network. The system's objectives are to distribute replicas of the content items in the network in a way that the most demanded contents will have replicas closer to the clients so that it will optimize the network utilization and will improve the users' experience. It also balances the load between the servers concentrating the traffic to the edges of the network

Content-aware resource allocation model for IPTV delivery networks

Nowadays, with the evolution of digital video broadcasting, as well as, the advent of high speed broadband networks, a new era of TV services has emerged known as IPTV. IPTV is a system that employs the high speed broadband networks to deliver TV services to the subscribers. From the service provider viewpoint, the challenge in IPTV systems is how to build delivery networks that exploits the resources efficiently and reduces the service cost, as well. However, designing such delivery networks affected by many factors including choosing the suitable network architecture, load balancing, resources waste, and cost reduction. Furthermore, IPTV contents characteristics, particularly; size, popularity, and interactivity play an important role in balancing the load and avoiding the resources waste for delivery networks. In this paper, we investigate the problem of resource allocation for IPTV delivery networks over the recent architecture, peer-service area architecture. The Genetic Algorithm as an optimization tool has been used to find the optimal provisioning parameters including storage, bandwidth, and CPU consumption. The experiments have been conducted on two data sets with different popularity distributions. The experiments have been conducted on two popularity distributions. The experimental results showed the impact of content status on the resource allocation process

Distributed dynamic replica placement and request redirection in content delivery networks

The Content Delivery Networks (CDN) paradigm is based on the idea to transparently move third-party content closer to the users. More specifically, content is replicated on CDN servers which are located close to the final users, and user requests are redirected to the "best" replica (e.g., the closest) in a transparent way, so that users perceive a better content access service. In this paper we address user requests redirection and replica placement in CDNs. Differently from previous solutions our scheme considers the two problems jointly and relies on distributed and localized schemes that can be implemented with little complexity and overhead, thus providing a new overall solution that effectively trades-off among the number of replicas, their utilization (i.e., how many users requests they serve), the distance from the best replica and the number of replica adds and removals. An OPNET based thorough performance evaluation has allowed us to assess the effectiveness of the proposed solution. By properly tuning the distributed heuristics parameters the CDN provider can have a strict control on the CDN network operations so that the desired trade-off between all the relevant performance metrics is achieved

Distributed Dynamic Replica Placement and Request Redirection in Content Delivery Networks

Abstract—The Content Delivery Networks (CDN) paradigm is based on the idea to transparently move third-party content closer to the users. More specifically, content is replicated on CDN servers which are located close to the final users, and user requests are redirected to the “best ” replica (e.g., the closest) in a transparent way, so that users perceive a better content access service. In this paper we address user requests redirection and replica placement in CDNs. Differently from previous solutions our scheme considers the two problems jointly and relies on distributed and localized schemes that can be implemented with little complexity and overhead, thus providing a new overall solution that effectively trades-off among the number of replicas, their utilization (i.e., how many users requests they serve), the distance from the best replica and the number of replica adds and removals. An OPNET based thorough performance evaluation has allowed us to assess the effectiveness of the proposed solution. By properly tuning the distributed heuristics parameters the CDN provider can have a strict control on the CDN network operations so that the desired trade-off between all the relevant performance metrics is achieved. I

Resilient Resource Allocation Schemes in Optical Networks

Recent studies show that deliberate malicious attacks performed by high-power sig- nals can put large amount of data under risk. We investigate the problem of sur- vivable optical networks resource provisioning scheme against malicious attacks, more specically crosstalk jamming attacks. These types of attacks may cause ser- vice disruption (or possibly service denial). We consider optical networks based on wavelength-division multiplexing (WDM) technology and two types of jamming at- tacks: in-band and out-of-band attacks. We propose an attack-aware routing and wavelength assignments (RWA) scheme to avoid or reduce the damaging effects of potential attacking signals on individual or multiple legitimate lightpaths travers- ing the same optical switches and links. An integer linear programs (ILPs) as well as heuristic approaches were proposed to solve the problem. We consider dynamic traffic where each demand is dened by its start time and a duration. Our results show that the proposed approaches were able to limit the vulnerability of lightpaths to jamming attacks. Recently, large-scale failures caused by natural disasters and/or deliberate at- tacks have left major parts of the networks damaged or disconnected. We also investigate the problem of disaster-aware WDM network resource provisioning in case of disasters. We propose an ILP and efficient heuristic to route the lightpaths in such a way that provides protection against disasters and minimize the network vi resources such as the number of wavelength links used in the network. Our models show that signicant resource savings can be achieved while accommodating users demands. In the last few years, optical networks using Space Division Multiplexing (SDM) has been proposed as a solution to the speed bottleneck anticipated in data center (DC) networks. To our knowledge the new challenges of designing such communica- tion systems have not been addressed yet. We propose an optimal approach to the problem of developing a path-protection scheme to handle communication requests in DC networks using elastic optical networking and space division multiplexing. We have formulated our problem as an ILP. We have also proposed a heuristic that can handle problems of practical size. Our simulations explore important features of our approach

Estudio, análisis y desarrollo de una red de distribución de contenido y su algoritmo de redirección de usuarios para servicios web y streaming

Esta tesis se ha creado en el marco de la línea de investigación de Mecanismos de Distribución de Contenidos en Redes IP, que ha desarrollado su actividad en diferentes proyectos de investigación y en la asignatura ¿Mecanismos de Distribución de Contenidos en Redes IP¿ del programa de doctorado ¿Telecomunicaciones¿ impartido por el Departamento de Comunicaciones de la UPV y, actualmente en el Máster Universitario en Tecnologías, Sistemas y Redes de Comunicación. El crecimiento de Internet es ampliamente conocido, tanto en número de clientes como en tráfico generado. Esto permite acercar a los clientes una interfaz multimedia, donde pueden concurrir datos, voz, video, música, etc. Si bien esto representa una oportunidad de negocio desde múltiples dimensiones, se debe abordar seriamente el aspecto de la escalabilidad, que pretende que el rendimiento medio de un sistema no se vea afectado conforme aumenta el número de clientes o el volumen de información solicitada. El estudio y análisis de la distribución de contenido web y streaming empleando CDNs es el objeto de este proyecto. El enfoque se hará desde una perspectiva generalista, ignorando soluciones de capa de red como IP multicast, así como la reserva de recursos, al no estar disponibles de forma nativa en la infraestructura de Internet. Esto conduce a la introducción de la capa de aplicación como marco coordinador en la distribución de contenido. Entre estas redes, también denominadas overlay networks, se ha escogido el empleo de una Red de Distribución de Contenido (CDN, Content Delivery Network). Este tipo de redes de nivel de aplicación son altamente escalables y permiten un control total sobre los recursos y funcionalidad de todos los elementos de su arquitectura. Esto permite evaluar las prestaciones de una CDN que distribuya contenidos multimedia en términos de: ancho de banda necesario, tiempo de respuesta obtenido por los clientes, calidad percibida, mecanismos de distribución, tiempo de vida al utilizar caching, etc. Las CDNs nacieron a finales de la década de los noventa y tenían como objetivo principal la eliminación o atenuación del denominado efecto flash-crowd, originado por una afluencia masiva de clientes. Actualmente, este tipo de redes está orientando la mayor parte de sus esfuerzos a la capacidad de ofrecer streaming media sobre Internet. Para un análisis minucioso, esta tesis propone un modelo inicial de CDN simplificado, tanto a nivel teórico como práctico. En el aspecto teórico se expone un modelo matemático que permite evaluar analíticamente una CDN. Este modelo introduce una complejidad considerable conforme se introducen nuevas funcionalidades, por lo que se plantea y desarrolla un modelo de simulación que permite por un lado, comprobar la validez del entorno matemático y, por otro lado, establecer un marco comparativo para la implementación práctica de la CDN, tarea que se realiza en la fase final de la tesis. De esta forma, los resultados obtenidos abarcan el ámbito de la teoría, la simulación y la práctica.Molina Moreno, B. (2013). Estudio, análisis y desarrollo de una red de distribución de contenido y su algoritmo de redirección de usuarios para servicios web y streaming [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31637TESI