Quality of service-aware routing and admission control for mobile ad hoc networks

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Quality of service-aware routing and admission control for mobile ad hoc networks

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Segurança e privacidade em terminologia de rede

Security and Privacy are now at the forefront of modern concerns, and drive a significant part of the debate on digital society. One particular aspect that holds significant bearing in these two topics is the naming of resources in the network, because it directly impacts how networks work, but also affects how security mechanisms are implemented and what are the privacy implications of metadata disclosure. This issue is further exacerbated by interoperability mechanisms that imply this information is increasingly available regardless of the intended scope. This work focuses on the implications of naming with regards to security and privacy in namespaces used in network protocols. In particular on the imple- mentation of solutions that provide additional security through naming policies or increase privacy. To achieve this, different techniques are used to either embed security information in existing namespaces or to minimise privacy ex- posure. The former allows bootstraping secure transport protocols on top of insecure discovery protocols, while the later introduces privacy policies as part of name assignment and resolution. The main vehicle for implementation of these solutions are general purpose protocols and services, however there is a strong parallel with ongoing re- search topics that leverage name resolution systems for interoperability such as the Internet of Things (IoT) and Information Centric Networks (ICN), where these approaches are also applicable.Segurança e Privacidade são dois topicos que marcam a agenda na discus- são sobre a sociedade digital. Um aspecto particularmente subtil nesta dis- cussão é a forma como atribuímos nomes a recursos na rede, uma escolha com consequências práticas no funcionamento dos diferentes protocols de rede, na forma como se implementam diferentes mecanismos de segurança e na privacidade das várias partes envolvidas. Este problema torna-se ainda mais significativo quando se considera que, para promover a interoperabili- dade entre diferentes redes, mecanismos autónomos tornam esta informação acessível em contextos que vão para lá do que era pretendido. Esta tese foca-se nas consequências de diferentes políticas de atribuição de nomes no contexto de diferentes protocols de rede, para efeitos de segurança e privacidade. Com base no estudo deste problema, são propostas soluções que, através de diferentes políticas de atribuição de nomes, permitem introdu- zir mecanismos de segurança adicionais ou mitigar problemas de privacidade em diferentes protocolos. Isto resulta na implementação de mecanismos de segurança sobre protocolos de descoberta inseguros, assim como na intro- dução de mecanismos de atribuiçao e resolução de nomes que se focam na protecçao da privacidade. O principal veículo para a implementação destas soluções é através de ser- viços e protocolos de rede de uso geral. No entanto, a aplicabilidade destas soluções extende-se também a outros tópicos de investigação que recorrem a mecanismos de resolução de nomes para implementar soluções de intero- perabilidade, nomedamente a Internet das Coisas (IoT) e redes centradas na informação (ICN).Programa Doutoral em Informátic

Modeling and Control of Server-based Systems

When deploying networked computing-based applications, proper resource management of the server-side resources is essential for maintaining quality of service and cost efficiency. The work presented in this thesis is based on six papers, all investigating problems that relate to resource management of server-based systems. Using a queueing system approach we model the performance of a database system being subjected to write-heavy traffic. We then evaluate the model using simulations and validate that it accurately mimics the behavior of a real test bed. In collaboration with Ericsson we model and design a per-request admission control scheme for a Mobile Service Support System (MSS). The model is then validated and the control scheme is evaluated in a test bed. Also, we investigate the feasibility to estimate the state of a server in an MSS using an event-based Extended Kalman Filter. In the brownout paradigm of server resource management, the amount of work required to serve a client is adjusted to compensate for temporary resource shortages. In this thesis we investigate how to perform load balancing over self-adaptive server instances. The load balancing schemes are evaluated in both simulations and test bed experiments. Further, we investigate how to employ delay-compensated feedback control to automatically adjust the amount of resources to deploy to a cloud application in the presence of a large, stochastic delay. The delay-compensated control scheme is evaluated in simulations and the conclusion is that it can be made fast and responsive compared to an industry-standard solution

Energy-aware service provisioning in P2P-assisted cloud ecosystems

Cotutela Universitat Politècnica de Catalunya i Instituto Tecnico de LisboaEnergy has been emerged as a first-class computing resource in modern systems. The trend has primarily led to the strong focus on reducing the energy consumption of data centers, coupled with the growing awareness of the adverse impact on the environment due to data centers. This has led to a strong focus on energy management for server class systems. In this work, we intend to address the energy-aware service provisioning in P2P-assisted cloud ecosystems, leveraging economics-inspired mechanisms. Toward this goal, we addressed a number of challenges. To frame an energy aware service provisioning mechanism in the P2P-assisted cloud, first, we need to compare the energy consumption of each individual service in P2P-cloud and data centers. However, in the procedure of decreasing the energy consumption of cloud services, we may be trapped with the performance violation. Therefore, we need to formulate a performance aware energy analysis metric, conceptualized across the service provisioning stack. We leverage this metric to derive energy analysis framework. Then, we sketch a framework to analyze the energy effectiveness in P2P-cloud and data center platforms to choose the right service platform, according to the performance and energy characteristics. This framework maps energy from the hardware oblivious, top level to the particular hardware setting in the bottom layer of the stack. Afterwards, we introduce an economics-inspired mechanism to increase the energy effectiveness in the P2P-assisted cloud platform as well as moving toward a greener ICT for ICT for a greener ecosystem.La energía se ha convertido en un recurso de computación de primera clase en los sistemas modernos. La tendencia ha dado lugar principalmente a un fuerte enfoque hacia la reducción del consumo de energía de los centros de datos, así como una creciente conciencia sobre los efectos ambientales negativos, producidos por los centros de datos. Esto ha llevado a un fuerte enfoque en la gestión de energía de los sistemas de tipo servidor. En este trabajo, se pretende hacer frente a la provisión de servicios de bajo consumo energético en los ecosistemas de la nube asistida por P2P, haciendo uso de mecanismos basados en economía. Con este objetivo, hemos abordado una serie de desafíos. Para instrumentar un mecanismo de servicio de aprovisionamiento de energía consciente en la nube asistida por P2P, en primer lugar, tenemos que comparar el consumo energético de cada servicio en la nube P2P y en los centros de datos. Sin embargo, en el procedimiento de disminuir el consumo de energía de los servicios en la nube, podemos quedar atrapados en el incumplimiento del rendimiento. Por lo tanto, tenemos que formular una métrica, sobre el rendimiento energético, a través de la pila de servicio de aprovisionamiento. Nos aprovechamos de esta métrica para derivar un marco de análisis de energía. Luego, se esboza un marco para analizar la eficacia energética en la nube asistida por P2P y en la plataforma de centros de datos para elegir la plataforma de servicios adecuada, de acuerdo con las características de rendimiento y energía. Este marco mapea la energía desde el alto nivel independiente del hardware a la configuración de hardware particular en la capa inferior de la pila. Posteriormente, se introduce un mecanismo basado en economía para aumentar la eficacia energética en la plataforma en la nube asistida por P2P, así como avanzar hacia unas TIC más verdes, para las TIC en un ecosistema más verde.Postprint (published version

Flexible application driven network striping over Wireless Wide Area Networks

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 157-161).Inverse multiplexing, or network striping, allows the construction of a high-bandwidth virtual channel from a collection of multiple low-bandwidth network channels. Striping systems usually employ a packet scheduling policy that allows applications to be oblivious of the way in which packets are routed to specific network channels. Though this is appropriate for many applications, many other applications can benefit from an approach that explicitly involves the application in the determination of the striping policy. Horde is middleware that facilitates flexible striping over Wireless Wide Area Network (WWAN) channels. Horde is unusual in that it separates the striping policy from the striping mechanism. It allows applications to describe network Quality-of-Service (QoS) objectives that the striping mechanism attempts to satisfy. Horde can be used by a set of data streams, each with its own QoS policy, to stripe data over a set of WWAN channels. The WWAN QoS variations observed across different channels and in time, provide opportunities to modulate stream QoS through scheduling. The key technical challenge in Horde is giving applications control over certain aspects of the data striping operation while at the same time shielding the application from low-level details. Horde exports a set of flexible abstractions replacing the application's network stack. Horde allows applications to express their policy goals as succinct network-QoS objectives. Each objective says something, relatively simple, about the sort of network QoS an application would like for some data stream(s). We present the Horde architecture, describe an early implementation, and examine how different policies can be used to modulate the quality-of-service observed across different independent data streams. Through experiments conducted on real and simulated network channels, we confirm our belief that the kind of QoS modulation Horde aims to achieve is realistic for actual applications.by Asfandyar Qureshi.M.Eng