Simulation and data analysis of peer-to-peer traffic for live video streaming

Evaluating and testing changes or configurations to peer-to-peer systems or even understanding their behaviour can be complicated. One approach is to simulate a large peer-to-peer system and visualise the results. In this master's thesis a study is performed to understand how an actual implementation of a hybrid peer-to-peer live video streaming system behaves and performs under different scenarios. The behaviour and performance of a hybrid live video streaming system consisting of an unstructured mesh-pull-based P2P network and a classic content delivery network solution is studied by simulating the system with different scenarios such as flash crowds and flash disconnects. The simulation system includes a network model taking latency and bandwidth into consideration. As expected the mesh-based system performed well under user churn. Although the system consisted of approximately 80% free-riders the utilisation of the content distribution network was reduced by 95% on average. The data analysis was successful in improving the system's overall performance. Furthermore, the visualisations and data analysis were used to understand the system's behaviour

Diseño centrado en calidad para la difusión Peer-to-Peer de video en vivo

El uso de redes Peer-to-Peer (P2P) es una forma escalable para ofrecer servicios de video sobre Internet. Este documento hace foco en la definición, desarrollo y evaluación de una arquitectura P2P para distribuir video en vivo. El diseño global de la red es guiado por la calidad de experiencia (Quality of Experience - QoE), cuyo principal componente en este caso es la calidad del video percibida por los usuarios finales, en lugar del tradicional diseño basado en la calidad de servicio (Quality of Service - QoE) de la mayoría de los sistemas. Para medir la calidad percibida del video, en tiempo real y automáticamente, extendimos la recientemente propuesta metodología Pseudo-Subjective Quality Assessment (PSQA). Dos grandes líneas de investigación son desarrolladas. Primero, proponemos una técnica de distribución de video desde múltiples fuentes con las características de poder ser optimizada para maximizar la calidad percibida en contextos de muchas fallas y de poseer muy baja señalización (a diferencia de los sistemas existentes). Desarrollamos una metodología, basada en PSQA, que nos permite un control fino sobre la forma en que la señal de video es dividida en partes y la cantidad de redundancia agregada, como una función de la dinámica de los usuarios de la red. De esta forma es posible mejorar la robustez del sistema tanto como sea deseado, contemplando el límite de capacidad en la comunicación. En segundo lugar, presentamos un mecanismo estructurado para controlar la topología de la red. La selección de que usuarios servirán a que otros es importante para la robustez de la red, especialmente cuando los usuarios son heterogéneos en sus capacidades y en sus tiempos de conexión.Nuestro diseño maximiza la calidad global esperada (evaluada usando PSQA), seleccionado una topología que mejora la robustez del sistema. Además estudiamos como extender la red con dos servicios complementarios: el video bajo demanda (Video on Demand - VoD) y el servicio MyTV. El desafío en estos servicios es como realizar búsquedas eficientes sobre la librería de videos, dado al alto dinamismo del contenido. Presentamos una estrategia de "caching" para las búsquedas en estos servicios, que maximiza el número total de respuestas correctas a las consultas, considerando una dinámica particular en los contenidos y restricciones de ancho de banda. Nuestro diseño global considera escenarios reales, donde los casos de prueba y los parámetros de configuración surgen de datos reales de un servicio de referencia en producción. Nuestro prototipo es completamente funcional, de uso gratuito, y basado en tecnologías bien probadas de código abierto

Data distribution over an overlay network

The Client-Server model based data distribution is inefficient for sessions with a large number of participants interested in receiving the same content at the same instant. Examples of such applications are live audio/video streaming, weather updates, stock tickers etc. The lack of global multicast infrastructure has made the research community to consider 'Overlay networks' as alternatives. Overlay networks require effective mechanisms for bootstrapping, constructing, maintaining and repairing the overlay. The effectiveness of these mechanisms influences the quality of the service experienced using the overlay network. In this thesis, we propose solutions that can be used by the overlay network to construct, maintain and repair the overlay. More precisely, the solutions that we propose can construct a minimum spanning tree for data distribution and identify capable (nodes with extra outbound degree) nodes using a decentralised design. Overlay networks can be classified into different types depending on the nature of the participants and the type of data distribution mechanism (tree, mesh). In the thesis, our focus is only on the overlay networks that uses tree based data distribution mechanism

Network overload avoidance by traffic engineering and content caching

The Internet traffic volume continues to grow at a great rate, now driven by video and TV distribution. For network operators it is important to avoid congestion in the network, and to meet service level agreements with their customers. This thesis presents work on two methods operators can use to reduce links loads in their networks: traffic engineering and content caching. This thesis studies access patterns for TV and video and the potential for caching. The investigation is done both using simulation and by analysis of logs from a large TV-on-Demand system over four months. The results show that there is a small set of programs that account for a large fraction of the requests and that a comparatively small local cache can be used to significantly reduce the peak link loads during prime time. The investigation also demonstrates how the popularity of programs changes over time and shows that the access pattern in a TV-on-Demand system very much depends on the content type. For traffic engineering the objective is to avoid congestion in the network and to make better use of available resources by adapting the routing to the current traffic situation. The main challenge for traffic engineering in IP networks is to cope with the dynamics of Internet traffic demands. This thesis proposes L-balanced routings that route the traffic on the shortest paths possible but make sure that no link is utilised to more than a given level L. L-balanced routing gives efficient routing of traffic and controlled spare capacity to handle unpredictable changes in traffic. We present an L-balanced routing algorithm and a heuristic search method for finding L-balanced weight settings for the legacy routing protocols OSPF and IS-IS. We show that the search and the resulting weight settings work well in real network scenarios

Smart PIN: performance and cost-oriented context-aware personal information network

The next generation of networks will involve interconnection of heterogeneous individual networks such as WPAN, WLAN, WMAN and Cellular network, adopting the IP as common infrastructural protocol and providing virtually always-connected network. Furthermore, there are many devices which enable easy acquisition and storage of information as pictures, movies, emails, etc. Therefore, the information overload and divergent content’s characteristics make it difficult for users to handle their data in manual way. Consequently, there is a need for personalised automatic services which would enable data exchange across heterogeneous network and devices. To support these personalised services, user centric approaches for data delivery across the heterogeneous network are also required. In this context, this thesis proposes Smart PIN - a novel performance and cost-oriented context-aware Personal Information Network. Smart PIN's architecture is detailed including its network, service and management components. Within the service component, two novel schemes for efficient delivery of context and content data are proposed: Multimedia Data Replication Scheme (MDRS) and Quality-oriented Algorithm for Multiple-source Multimedia Delivery (QAMMD). MDRS supports efficient data accessibility among distributed devices using data replication which is based on a utility function and a minimum data set. QAMMD employs a buffer underflow avoidance scheme for streaming, which achieves high multimedia quality without content adaptation to network conditions. Simulation models for MDRS and QAMMD were built which are based on various heterogeneous network scenarios. Additionally a multiple-source streaming based on QAMMS was implemented as a prototype and tested in an emulated network environment. Comparative tests show that MDRS and QAMMD perform significantly better than other approaches

Optimización de la estrategia de selección de piezas de video en redes P2P.

El tráfico debido a redes Peer-to-Peer (P2P) sobre la infraestructura de Internet es superior a la suma de las restantes aplicaciones. Si bien esto último es un gran desafío económico para los proveedores de servicios de Internet, las prestaciones de estas redes son tan importantes en la actualidad (interactividad y comunicación multimedia, descarga de contenidos de video, música, transacciones y trabajos cooperativos, entre tantos otros) que motivan a promover políticas de diseño tanto eficaces como eficientes. Las redes P2P imponen un nuevo paradigma de comunicación en base a la cooperación entre pares, que se contrasta con los anteriores modelos cliente-servidor. Ahora los contenidos se fraccionan y distribuyen en la red. Los pares se benefician de los recursos de los restantes para lograr obtener el contenido entero. Hay dos elementos estratégicos claves en el diseño de redes de pares: la decisión de pares con los cuales cooperar, o “estrategia de selección de pares”, y las piezas que se deben descargar una vez establecida la comunicación con un par, o “estrategia de selección de piezas”. Esta tesis se concentra en la estrategia de selección de piezas. En base a un modelo matemático simple, se proponen nuevas técnicas de estrategia de selección de piezas, que superan la calidad de anteriores técnicas. Se introduce un Problema de Optimización Combinatoria (COP) centrado en la calidad de experiencia (QoE), cuyo conjunto de variables de decisión es el de estrategias de selección de piezas. La experiencia en la resolución de este problema sugiere bondades en ciertas estrategias. Las mismas se introducen en una plataforma real de videostreaming denominada GoalBit, que es la primera red P2P cuyos protocolos y códigos son públicos, y posee amplia difusión actualmente en Internet

Use of locator/identifier separation to improve the future internet routing system

The Internet evolved from its early days of being a small research network to become a critical infrastructure many organizations and individuals rely on. One dimension of this evolution is the continuous growth of the number of participants in the network, far beyond what the initial designers had in mind. While it does work today, it is widely believed that the current design of the global routing system cannot scale to accommodate future challenges. In 2006 an Internet Architecture Board (IAB) workshop was held to develop a shared understanding of the Internet routing system scalability issues faced by the large backbone operators. The participants documented in RFC 4984 their belief that "routing scalability is the most important problem facing the Internet today and must be solved." A potential solution to the routing scalability problem is ending the semantic overloading of Internet addresses, by separating node location from identity. Several proposals exist to apply this idea to current Internet addressing, among which the Locator/Identifier Separation Protocol (LISP) is the only one already being shipped in production routers. Separating locators from identifiers results in another level of indirection, and introduces a new problem: how to determine location, when the identity is known. The first part of our work analyzes existing proposals for systems that map identifiers to locators and proposes an alternative system, within the LISP ecosystem. We created a large-scale Internet topology simulator and used it to compare the performance of three mapping systems: LISP-DHT, LISP+ALT and the proposed LISP-TREE. We analyzed and contrasted their architectural properties as well. The monitoring projects that supplied Internet routing table growth data over a large timespan inspired us to create LISPmon, a monitoring platform aimed at collecting, storing and presenting data gathered from the LISP pilot network, early in the deployment of the LISP protocol. The project web site and collected data is publicly available and will assist researchers in studying the evolution of the LISP mapping system. We also document how the newly introduced LISP network elements fit into the current Internet, advantages and disadvantages of different deployment options, and how the proposed transition mechanism scenarios could affect the evolution of the global routing system. This work is currently available as an active Internet Engineering Task Force (IETF) Internet Draft. The second part looks at the problem of efficient one-to-many communications, assuming a routing system that implements the above mentioned locator/identifier split paradigm. We propose a network layer protocol for efficient live streaming. It is incrementally deployable, with changes required only in the same border routers that should be upgraded to support locator/identifier separation. Our proof-of-concept Linux kernel implementation shows the feasibility of the protocol, and our comparison to popular peer-to-peer live streaming systems indicates important savings in inter-domain traffic. We believe LISP has considerable potential of getting adopted, and an important aspect of this work is how it might contribute towards a better mapping system design, by showing the weaknesses of current favorites and proposing alternatives. The presented results are an important step forward in addressing the routing scalability problem described in RFC 4984, and improving the delivery of live streaming video over the Internet