The main goal of today’s wireless Service Providers (SPs) is to provide optimum and ubiquitous service for roaming users while maximizing the SPs own monetary profits. The fundamental objective is to support such requirements by providing solutions that are adaptive to varying conditions in highly mobile and heterogeneous, as well as dynamically changing wireless network infrastructures. This can only be achieved through well-designed management systems. Most techniques fail to utilize the knowledge gained from previously tested reconfiguration strategies on system and network behaviour. This dissertation presents a novel framework that automates the cooperation among a number of wireless SPs facing the challenge of meeting strict service demands for a large number of mobile users. The proposed work employs a novel policy-based system configuration model to automate the process of adapting new network policies. The proposed framework relies on the assistance of a real-time simulator that runs as a constant background process in order to continuously find optimal policy configurations for the SPs’ networks. To minimize the computational time needed to find these configurations, a modified tabu-search scheme is proposed. An objective is to efficiently explore the space of network configurations in order to find optimal network decisions and provide a service performance that adheres to contracted service level agreements. This framework also relies on a distributed Quality of Service (QoS) monitoring scheme. The proposed scheme relies on the efficient identification of candidate QoS monitoring users that can efficiently submit QoS related measurements on behalf of their neighbors. These candidate users are chosen according to their devices’ residual power and transmission capabilities and their estimated remaining service lifetime. Service monitoring users are then selected from these candidates using a novel user-to-user semantic similarity matching algorithm. This step ensures that the monitoring users are reporting on behalf of other users that are highly similar to them in terms of their mobility, used services and device profiles. Experimental results demonstrate the significant gains achieved in terms of the reduced traffic overhead and overall consumed users’ devices power while achieving a high monitoring accuracy, adaptation time speedup, base station load balancing, and individual providers’ payoffs.

The main goal of today’s wireless Service Providers (SPs) is to provide optimum and ubiquitous service for roaming users while maximizing the SPs own monetary profits. The fundamental objective is to support such requirements by providing solutions that are adaptive to varying conditions in highly mobile and heterogeneous, as well as dynamically changing wireless network infrastructures. This can only be achieved through well-designed management systems. Most techniques fail to utilize the knowledge gained from previously tested reconfiguration strategies on system and network behaviour. This dissertation presents a novel framework that automates the cooperation among a number of wireless SPs facing the challenge of meeting strict service demands for a large number of mobile users. The proposed work employs a novel policy-based system configuration model to automate the process of adapting new network policies. The proposed framework relies on the assistance of a real-time simulator that runs as a constant background process in order to continuously find optimal policy configurations for the SPs’ networks. To minimize the computational time needed to find these configurations, a modified tabu-search scheme is proposed. An objective is to efficiently explore the space of network configurations in order to find optimal network decisions and provide a service performance that adheres to contracted service level agreements. This framework also relies on a distributed Quality of Service (QoS) monitoring scheme. The proposed scheme relies on the efficient identification of candidate QoS monitoring users that can efficiently submit QoS related measurements on behalf of their neighbors. These candidate users are chosen according to their devices’ residual power and transmission capabilities and their estimated remaining service lifetime. Service monitoring users are then selected from these candidates using a novel user-to-user semantic similarity matching algorithm. This step ensures that the monitoring users are reporting on behalf of other users that are highly similar to them in terms of their mobility, used services and device profiles. Experimental results demonstrate the significant gains achieved in terms of the reduced traffic overhead and overall consumed users’ devices power while achieving a high monitoring accuracy, adaptation time speedup, base station load balancing, and individual providers’ payoffs.

Avanços nas tecnologias de comunicação e processamento de sinais além de mudar a forma de como realizar negócios em todo o mundo, têm motivado o surgimento de serviços e aplicações multimídia na Internet de forma crescente. Como conseqüência, é possível conceber, desenvolver, implantar e operar serviços de distribuição de vídeo digital na Internet, tanto na abordagem sob-demanda quanto ao vivo. Com o aumento das aplicações multimídia na rede, torna-se cada vez mais complexo e necessário definir um modelo eficiente que possa realizar o gerenciamento efetivo e integrado de todos os elementos e serviços que compõe um sistema computacional. Pensando assim, este trabalho propõe uma arquitetura de gerenciamento baseado em políticas aplicada à distribuição de conteúdo multimídia com controle de QoS (Quality of Service) em redes de sobreposição (overlay). A arquitetura é baseada nos padrões de gerenciamento por políticas definida pela IETF (Internet Engineering Task Force) que, através de informações contextuais (rede e clientes) administra os serviços disponíveis no sistema. Faz uso dos requisitos de QoS providos pela rede de distribuição e os compara com os requisitos mínimos exigidos pelos perfis das aplicações previamente mapeados em regras de políticas. Dessa forma é possível controlar e administrar os elementos e serviços do sistema, afim de melhor distribuir recursos aos usuários deste sistema. / Advances in communication technologies and signal processing have not only changed the way business is conducted around the world, but have also driven the development of services and multimedia applications on the Internet. As a result, it is possible to design, develop, deploy and operate services for digital video distribution on the Internet, both according to an on-demand approach and live. Because of the increase in multimedia applications on the network, it has become increasingly more complex and necessary to define an efficient architecture that can achieve the effective and integrated management of all the elements and services that compose a computer system. With this in mind, this study proposes developing a robust and efficient architecture based on IETF (Internet Engineering Task Force) policy management standards applied to multimedia distribution content with QoS (Quality of Service) control in Overlay Networks. This architecture makes use of QoS requirements provided by the distribution network and compares them to the minimum requirements demanded by each type of application previously mapped in the policy rules. This system makes it possible to control and manage system information and services and also to distribute resources to system users better.

Avanços nas tecnologias de comunicação e processamento de sinais além de mudar a forma de como realizar negócios em todo o mundo, têm motivado o surgimento de serviços e aplicações multimídia na Internet de forma crescente. Como conseqüência, é possível conceber, desenvolver, implantar e operar serviços de distribuição de vídeo digital na Internet, tanto na abordagem sob-demanda quanto ao vivo. Com o aumento das aplicações multimídia na rede, torna-se cada vez mais complexo e necessário definir um modelo eficiente que possa realizar o gerenciamento efetivo e integrado de todos os elementos e serviços que compõe um sistema computacional. Pensando assim, este trabalho propõe uma arquitetura de gerenciamento baseado em políticas aplicada à distribuição de conteúdo multimídia com controle de QoS (Quality of Service) em redes de sobreposição (overlay). A arquitetura é baseada nos padrões de gerenciamento por políticas definida pela IETF (Internet Engineering Task Force) que, através de informações contextuais (rede e clientes) administra os serviços disponíveis no sistema. Faz uso dos requisitos de QoS providos pela rede de distribuição e os compara com os requisitos mínimos exigidos pelos perfis das aplicações previamente mapeados em regras de políticas. Dessa forma é possível controlar e administrar os elementos e serviços do sistema, afim de melhor distribuir recursos aos usuários deste sistema. / Advances in communication technologies and signal processing have not only changed the way business is conducted around the world, but have also driven the development of services and multimedia applications on the Internet. As a result, it is possible to design, develop, deploy and operate services for digital video distribution on the Internet, both according to an on-demand approach and live. Because of the increase in multimedia applications on the network, it has become increasingly more complex and necessary to define an efficient architecture that can achieve the effective and integrated management of all the elements and services that compose a computer system. With this in mind, this study proposes developing a robust and efficient architecture based on IETF (Internet Engineering Task Force) policy management standards applied to multimedia distribution content with QoS (Quality of Service) control in Overlay Networks. This architecture makes use of QoS requirements provided by the distribution network and compares them to the minimum requirements demanded by each type of application previously mapped in the policy rules. This system makes it possible to control and manage system information and services and also to distribute resources to system users better.

Nesta dissertação é apresentada uma avaliação da viabilidade de obtenção de operações atômicas para a configuração de múltiplos dispositivos em uma rede de computadores. Em especial, é tratada a configuração de dispositivos a partir do gerenciamento baseado em políticas. Nestes casos, a necessidade de operações atômicas vem do fato de que uma aplicação de política que falha em um determinado dispositivo pode levar a um estado inconsistente em uma rede da qual se deseja um comportamento uniforme e global. Assim, este trabalho analisa requisitos, limitações, implicações e alternativas de implementação para a obtenção de atomicidade na aplicação de políticas. Como uma proposta de solução para este problema é definido um protocolo de consenso a ser utilizado entre os participantes da aplicação da política na rede. Tal protocolo é implementado utilizando Web Services e integrado junto ao sistema de gerenciamento baseado em políticas denominado QAME. Por fim, a solução é avaliada através de testes em um cenário de testes composto por um cluster de computadores. / This work presents an investigation of the viability of performing atomic operations during the configuration of multiple devices in a computer network. Specially, the configuration of devices using policy-based network management is addressed. In these cases, the need of atomic operations comes from the fact that a policy application that fails in a certain device can lead to an inconsistent state in a network from which an uniform and global behavior is desired. Thus, this work analyses requirements, limitations, implications, and alternatives for obtaining atomicity in policy deployment. As a solution for this problem, this work defines a consensus protocol to be used by the participants in the policy deployment process. Such protocol was implemented using Web Services and integrated to a policy-based network management system named QAME. At last, the proposed solution is evaluated through a set of tests performed over a testing scenario composed of a high-performance cluster.

Nesta dissertação é apresentada uma avaliação da viabilidade de obtenção de operações atômicas para a configuração de múltiplos dispositivos em uma rede de computadores. Em especial, é tratada a configuração de dispositivos a partir do gerenciamento baseado em políticas. Nestes casos, a necessidade de operações atômicas vem do fato de que uma aplicação de política que falha em um determinado dispositivo pode levar a um estado inconsistente em uma rede da qual se deseja um comportamento uniforme e global. Assim, este trabalho analisa requisitos, limitações, implicações e alternativas de implementação para a obtenção de atomicidade na aplicação de políticas. Como uma proposta de solução para este problema é definido um protocolo de consenso a ser utilizado entre os participantes da aplicação da política na rede. Tal protocolo é implementado utilizando Web Services e integrado junto ao sistema de gerenciamento baseado em políticas denominado QAME. Por fim, a solução é avaliada através de testes em um cenário de testes composto por um cluster de computadores. / This work presents an investigation of the viability of performing atomic operations during the configuration of multiple devices in a computer network. Specially, the configuration of devices using policy-based network management is addressed. In these cases, the need of atomic operations comes from the fact that a policy application that fails in a certain device can lead to an inconsistent state in a network from which an uniform and global behavior is desired. Thus, this work analyses requirements, limitations, implications, and alternatives for obtaining atomicity in policy deployment. As a solution for this problem, this work defines a consensus protocol to be used by the participants in the policy deployment process. Such protocol was implemented using Web Services and integrated to a policy-based network management system named QAME. At last, the proposed solution is evaluated through a set of tests performed over a testing scenario composed of a high-performance cluster.

Nesta dissertação é apresentada uma avaliação da viabilidade de obtenção de operações atômicas para a configuração de múltiplos dispositivos em uma rede de computadores. Em especial, é tratada a configuração de dispositivos a partir do gerenciamento baseado em políticas. Nestes casos, a necessidade de operações atômicas vem do fato de que uma aplicação de política que falha em um determinado dispositivo pode levar a um estado inconsistente em uma rede da qual se deseja um comportamento uniforme e global. Assim, este trabalho analisa requisitos, limitações, implicações e alternativas de implementação para a obtenção de atomicidade na aplicação de políticas. Como uma proposta de solução para este problema é definido um protocolo de consenso a ser utilizado entre os participantes da aplicação da política na rede. Tal protocolo é implementado utilizando Web Services e integrado junto ao sistema de gerenciamento baseado em políticas denominado QAME. Por fim, a solução é avaliada através de testes em um cenário de testes composto por um cluster de computadores. / This work presents an investigation of the viability of performing atomic operations during the configuration of multiple devices in a computer network. Specially, the configuration of devices using policy-based network management is addressed. In these cases, the need of atomic operations comes from the fact that a policy application that fails in a certain device can lead to an inconsistent state in a network from which an uniform and global behavior is desired. Thus, this work analyses requirements, limitations, implications, and alternatives for obtaining atomicity in policy deployment. As a solution for this problem, this work defines a consensus protocol to be used by the participants in the policy deployment process. Such protocol was implemented using Web Services and integrated to a policy-based network management system named QAME. At last, the proposed solution is evaluated through a set of tests performed over a testing scenario composed of a high-performance cluster.

Policy based network management is a promising approach for provisioning and management of quality of service in mobile ad hoc networks. In this thesis, we focus on performance evaluation of this approach in context of the amount of service received by certain nodes called policy execution points (PEPs) or policy clients from certain specialized nodes called the policy decision points (PDPs) or policy servers. We develop analytical models for the study of the system behavior under two scenarios; a simple Markovian scenario where we assume that the random variables associated with system processes follow an exponential distribution and a more complex non-Markovian scenario where we model the system processes according to general distribution functions as observed through simulation. We illustrate that the simplified Markovian model provides a reasonable indication of the trend of the service availability seen by policy clients and highlight the need for an exact analysis of the system without relying on Poisson assumptions for system processes. In the case of the more exact non-Markovian analysis, we show that our model gives a close approximation to the values obtained via empirical methods. Stochastic Petri Nets are used as performance evaluation tools in development and analysis of these system models. / Master of Science

Managing mobile ad hoc networks (MANETs) presents new challenges due to the need for a distributed management mechanism that can efficiently adapt to the dynamic nature of these networks. In particular, provisioning and management of Quality of Service (QoS) in such networks remains a challenging task. Previous works in this field have focused largely on the monitoring and data collection aspects of network management; literature on the provisioning of devices and protocol support for MANET configuration is scarce. One approach for QoS provisioning and management in the Internet that has met with considerable interest in the networking community is that of Policy-Based Network Management (PBNM). However, its application has been so far limited mainly to fixed high-bandwidth networks. In this research, we apply the PBNM concept, for the first time, for managing QoS in ad hoc networks. We formulate a framework to understand the various crucial components that should comprise an ad hoc network management system. We propose a taxonomy of policy architectures to classify the various feasible architectures into distinct categories. Based on our assessment using the taxonomy, we identify architectures that seem promising for managing ad hoc networks. We propose a solution suite to address the different challenges in deploying policy-based management in MANETs. These solutions include k-hop clustering, Dynamic Service Redundancy (DynaSeR), inter-domain policy negotiation, and automated service discovery. We propose extensions to the standard Common Open Policy Service (COPS) protocol and suggest methods for cross-layer interaction to implement our solutions. Our methodology focuses on both a prototype implementation and experimental analysis using wired and wireless testbed networks, and modeling and performance evaluation using simulation. The whole exercise of conducting experiments provided valuable insight into the challenges of operating in an actual ad hoc network environment; implementation and testing facilitated assessment of the feasibility of our proposed schemes. Simulation allowed us to evaluate our solutions for different cluster sizes, network densities, and node mobility. The scalability of our solutions was tested with networks of up to 100 nodes. In general, average service availability for the PBNM system improved as the cluster size increased, with decreased COPS connection overhead (the tradeoff is increased unpredictability, longer response time, and resource requirements at intermediate nodes to support larger clusters). We were also able to determine that, for a given cluster size, our proposed delegation scheme resulted in a 10 to 25% improvement in service availability. Using our proposed time-based heuristic, savings on the order of 50 to 400% were obtained in the service discovery overhead for larger cluster sizes. We also validated some of the simulation results against proof-of-concept experiments conducted using the testbed. We presented a working illustration of our PBNM system prototype by demonstrating its application for managing QoS for multimedia and real-time mission critical applications in a multi-domain ad hoc network. The policy-based approach is a promising one for the management of MANETs, but it requires the flexibility to adapt to a constantly changing environment. Through experimental studies and simulation, we were able to determine that using our proposed solution suite and through the addition of a set of extensions to the COPS protocol, we can achieve our objective of a self-organizing, robust, and efficient PBNM system for managing MANETs. / Ph. D.

Sistemas corporativos modernos cada vez mais dependentes da rede e a integração de serviços entorno do modelo TCP/IP elevam a exigência de Qualidade de Serviço da infraestrutura de TI. Neste cenário, o dinamismo das redes atuais em conjunto com os novos requisitos de QoS exigem que a infra-estrutura de TI seja mais autônoma e confiável. Para tratar esta questão, o modelo de Gerenciamento de Redes Baseado em Políticas, proposto pelo IETF, vem se consolidando como uma abordagem para controlar o comportamento da rede através do controle das configurações dos seus dispositivos. Porém, o foco deste modelo é o gerenciamento de políticas internas a um domínio administrativo. Esta característica faz com que o modelo possua algumas limitações, tais como a incapacidade de estabelecer qualquer tipo de coordenação entre diferentes PDPs e a impossibilidade de reagir a eventos externos. Visando agregar autonomia ao modelo de gerenciamento baseado em políticas, este trabalho propõe uma arquitetura em camadas que empregue os conceitos de Autonomic Computing relacionados a: i) adaptação dinâmica dos recursos gerenciados em resposta às mudanças no ambiente, ii) integração com sistemas de gerenciamento de outros domínios através do recebimento de notificações destes, iii) capacidade de planejar ações de gerenciamento e iv) promoção de ações de gerenciamento que envolvam mais de um domínio administrativo, estabelecendo uma espécie de coordenação entre PDPs. Para a implementação destes conceitos, a arquitetura prevê o uso de uma camada peerto- peer (P2P) sobre a plataforma de políticas. Desta forma, a partir de uma notificação recebida, a camada P2P planeja ações visando adaptar o comportamento da rede aos eventos ocorridos na infra-estrutura de TI. As ações planejadas traduzem-se em inclusões ou remoções de políticas da plataforma de políticas responsável por gerenciar a configuração dos dispositivos de rede. Para notificações que envolvam recursos de mais de um domínio administrativo, os peers de gerenciamento agem de forma coordenada para implantar as devidas ações em cada domínio. A arquitetura proposta foi projetada com foco em prover QoS em uma rede com suporte à DiffServ, embora acredite-se que a sua estrutura seja genérica o bastante para ser aplicada a outros contextos. Como estudo de caso, foi analisado o emprego da arquitetura em resposta a eventos gerados por uma grade computacional. Foi elaborado ainda um protótipo da arquitetura utilizando o Globus Toolkit 4 como fonte de eventos. / Modern corporative systems becoming more dependent of the network and the integration of services around the TCP/IP model increase the requirement of Quality of Service (QoS) of the IT infrastructure. In this scene, the dynamism of current networks together with the new requirements of QoS demands a more autonomous and reliable IT infrastructure. To address this issue, the model of Police Based Network Management, proposed by IETF, has been consolidated as an approach to control the behavior of the network through the control of the configurations of its devices. However, the focus of this model is the management of the policies internal to an administrative domain. This feature brings some limitations to the model, such as the incapacity to establish any kind of coordination between different PDPs and the impossibility to react to external events. Aiming at to add autonomy to the model of Policy Based Network Management, this work proposes a layered architecture based on the concepts of Autonomic Computing related to: i) the dynamic adaptation of the managed resources in response to changes in the environment, ii) integration with management systems of other domains through the reception of notifications of these systems, iii) ability of planning the management actions and iv) execution of multi-domain management actions, establishing a kind of coordination between PDPs. To implement these concepts, the architecture was designed with a peer-to-peer layer above the policy platform. Thus, from a received notification, the P2P layer plans actions aiming to adapt the network behavior in response to the events occurred in the IT infrastructure. The planned actions are, actually, inclusions or removals of policies in the policy platform responsible for the management of the network devices configuration. For notifications related with resources of more than one administrative domain, the management peers act in a coordinated way in order to establish the suitable actions in each domain. The proposed architecture was designed with focus in providing QoS in a network with support to DiffServ, although we believe that its structure is generic enough to be applied to other contexts. As case study, it was analyzed the use of the architecture in response to events generated by a computational grid. Additionally, a prototype of the architecture was build making use of Globus Toolkit 4 as an event source.