Um dos objetivos das próximas gerações dos sistemas de comunicação é permitir que os usuários acessem e distribuam um ou mais serviços a qualquer hora, em qualquer lugar, independentemente do tipo de terminal (telefone convencional, telefone celular, assistentes pessoais digitais, notebooks, dentre outros) ou da tecnologia da rede de acesso utilizados. Esse cenário é denominado convergência de serviços utilizando-se redes heterogêneas, e em tal realidade, as arquiteturas de qualidade de serviço existentes em cada uma das tecnologias dos sistemas de comunicação não oferecem mecanismos de interoperabilidade e em diversos casos não há controle sob os fluxos de dados uma vez admitido na infraestrutura do sistema de comunicação, assim como questões de handover heterogêneo não são tratadas. A tese propõe uma arquitetura para controle de Qualidade de Serviço para um ambiente heterogêneo composto de backbones IP e redes de acesso de diversas tecnologias, sendo tal arquitetura composta de agentes autônomos e distribuídos nos equipamentos de um sistema de comunicação; assim como.controles baseados no comportamento de uma região de um sistema de comunicação e apoiados na teoria e princípios de sistemas complexos. Os agentes da arquitetura proposta utilizando o princípio de preferential attachment mostraram-se eficientes na determinação do caminho de melhor condição de qualidade de serviços. Os componentes da arquitetura proposta estão localizados em cada equipamento de comunicação, desde o dispositivo do usuário até o provedor de serviços. As medições realizadas pelos agentes e utilizando um algoritmo baseado no conceito de preferential attachment permitiram ao agente alterar o caminho de um fluxo de dados durante sua transmissão para outros caminhos que apresentaram condições mais adequadas de acordo com os parâmetros de QoS. A decisão é baseada no contrato de qualidade de serviço especificado entre usuário e provedor de serviço e, considerando sob controle todos os elementos envolvidos na comunicação; tem-se controle distribuído de qualidade de serviço fim a fim. / One of the targets of the next generation communication systems is to provide access to any service, to any user, anytime, anywhere, regardless the access network technology or type of user device (mobile phone, PDA, personal computer, and so on). This scenario is called convergence of services by heterogeneous networks, and in such scenario quality of service mechanisms presented in legacy communication systems do not provide mechanisms for interoperability between communication systems nor control data flows after control admission in the border of the communication systems. The heterogeneous handover is also not handled by such QoS architectures. This thesis proposes a QoS control architecture for an heterogeneous communication systems composed by IP backbones and several access networks for several kind of technologies. This architecture is composed by a multiagent system and has controls based on the local behavior of the communication system and supported by complex systems theory. The agent decision algorithm is based on preferential attachment concept and the experimentation results indicate that agents could identify a better path to handle a data flow according to QoS parameters. The agents decided to change the path used to transmit the flow data autonomously and according to quality of service contract between user and service provider. The measurements in the test based on preferential attachment algorithm was useful in order agent change flow data path during data flow transmission to other paths with better conditions according to QoS requisites. The agent decision is based on the parameter values defined between end user and service provider. Considering the control elements from proposed architecture it was achieved end-to-end distributed control.

Os dispositivos indicadores de faltas são utilizados para sinalizar a passagem de uma corrente de curto-circuito nos alimentadores de distribuição de energia elétrica. Tais dispositivos permitem uma redução significativa no tempo de inspeção das equipes de manutenção durante a busca pela região faltosa. Entretanto, associada a estes dispositivos, encontra-se uma elevada taxa de falhas de suas operações, que comprometem a confiabilidade do equipamento e, conseqüentemente, o tempo de localização de faltas. Neste trabalho é apresentada uma metodologia de ensaios laboratoriais a fim de complementar os testes padrões dos fabricantes de indicadores de faltas, buscando-se então identificar os fatores que colaboram para as falhas de tais equipamentos. Os resultados obtidos mostraram a eficiência da metodologia desenvolvida em detectar falhas de operação dos indicadores de faltas, as quais também não puderam ser detectadas por testes fornecidos por fabricantes. / Fault Indicators are devices used to signal the passage of a short-circuit current in electricity distribution feeders. Such devices allow a significant reduction in patrol time by maintenance linemen during the search for the faulty region. However, associated with these devices, it is a high failure rate of operations that compromise the equipment reliability and, consequently, the time of fault location. This work presents a new methodology for single-phase laboratory tests in order to complement the standard tests accomplished by the manufacturers of fault indicators, aiming to then identify the factors that contribute to failures of such equipment. The results showed the efficiency of the methodology developed to detect operation failures of faults indicators that could not be detected by tests provided by manufacturers.

Bien qu'Internet soit considéré comme le grand succès de ces dernières années, il est devenu une infrastructure critique à cause de l'absence de changements dans le réseau cœur et de la rigidité des équipements déployés. La mise en place et le déploiement des nouveaux services réseau sont devenus difficiles et coûteux. La virtualisation des réseaux a été présentée comme un nouveau paradigme pour palier aux problèmes de l’architecture actuelle de l'Internet. Dans ce travail de thèse, nous présentons la virtualisation des réseaux et les réseaux définis par logiciels (SDN) comme solution avec laquelle les fournisseurs de services peuvent offrir, au travers des réseaux virtuels (VN), des nouveaux services aux utilisateurs avec une meilleure qualité de service, tout en optimisant l'utilisation des ressources réseaux physiques. La première contribution consiste à démontrer le potentiel de SDN dans la gestion de la QoS dans le contexte d’un réseau domestique virtualisé. Nous proposons et implémentons le mécanisme ''FlowQoS'' qui peut être déployé par un fournisseur d’accès Internet au niveau de la boucle locale ou bien dans la passerelle domestique. Les mesures des performances montrent que cette solution permet de partager la bande passante entre plusieurs applications selon la configuration définie par l’utilisateur pour garantir la QoS pour chaque trafic actif. La seconde contribution est une modélisation, par la théorie des jeux, de l’interaction entre les fournisseurs de services et les fournisseurs de l’infrastructure pour le partage dynamique de l’infrastructure physique entre plusieurs VN avec différents besoins en QoS. Il s'agit d'un ensemble de jeux non-coopératifs pour modéliser la phase de négociation et celle de l’allocation dynamique des nœuds et des liens physiques pour chaque VN déployé. La troisième contribution porte sur une approche prédictive qui permet d’offrir un contrôle adaptatif de l’allocation de bande passante dans le but de réduire les délais des paquets d'un VN sur chaque lien physique. Ces deux dernières contributions offrent des modèles de partage dynamique des ressources d’une infrastructure physique tout en garantissant la QoS pour chaque VN / Internet has been successful in the recent years. The critical infrastructure of the internet has become stagnant due to the absence of changes in the core networks and stiffness of deployed equipment. It has become difficult and expensive to deploy new network services. Network virtualization is a new paradigm to overcome this problem. In this thesis, we present network virtualization and Software Defined Networking (SDN) as a solution that can be used by service providers. It enables them to provide new services to users through virtual networks (VNs) with better quality of service while optimizing the use of physical network resources. Firstly, we demonstrate the potential of SDN in the QoS management ofa virtualized home network (VN). We propose and implement ''FlowQoS'', a mechanism that can be deployed by an Internet Service Provider in the last-mile hop or in the home gateway. Performance measurements show that this solution can share bandwidth between applications according to user-defined configuration to guarantee QoS for each active traffic. The second contribution is modeling the interaction between service providers and infrastructure providers using game theoretic framework to offer dynamic sharing of physical infrastructure across multiple VN with different QoS requirements. We present a set of non-cooperative games to model the negotiation phase and the dynamic allocation of nodes and physical links for each deployed VN. Finally we focus on a predictive approach that allows an adaptive control of bandwidth allocation in order to reduce the packet delays for a given VN on each physical link. The last two contributions offer dynamic sharing models of physical infrastructure resources while guaranteeing the QoS for each VN

[pt] As disciplinas de Controle de Admissão constituem um recurso importante para a obtenção de Qualidade de Serviço em redes de comunicação. Nesse trabalho, é feito um estudo a respeito da aplicação do Controle de Admissão à Internet. Utilizando- se o software ns-2, é avaliado o desempenho de alguns desses mecanismos em cenários distintos e sob diversas condições de tráfego. / [en] Admission control disciplines are un important resource in the search for Quality of Service on communications networks. In this work, we studt the Admission control applications on the Internet. Using the ns-2 networks simulation software, we evaluate the performance of some of these mechanisms on distinct scenarios, and under several circunstances and traffic conditions.

L’évolution des services en ligne et l’avènement du big data ont favorisé l’introduction de l’internet dans tous les aspects de notre vie : la communication et l’échange des informations (exemple, Gmail et Facebook), la recherche sur le web (exemple, Google), l’achat sur internet (exemple, Amazon) et le streaming vidéo (exemple, YouTube). Tous ces services sont hébergés sur des sites physiques appelés centres de données ou data centers qui sont responsables de stocker, gérer et fournir un accès rapide à toutes les données. Tous les équipements constituants le système d’information d’une entreprise (ordinateurs centraux, serveurs, baies de stockage, équipements réseaux et de télécommunications, etc) peuvent être regroupés dans ces centres de données. Cette évolution informatique et technologique a entrainé une croissance exponentielle des centres de données. Cela pose des problèmes de coût d’installation des équipements, d’énergie, d’émission de chaleur et de performance des services offerts aux clients. Ainsi, l’évolutivité, la performance, le coût, la fiabilité, la consommation d’énergie et la maintenance sont devenus des défis importants pour ces centres de données. Motivée par ces défis, la communauté de recherche a commencé à explorer de nouveaux mécanismes et algorithmes de routage et des nouvelles architectures pour améliorer la qualité de service du centre de données. Dans ce projet de thèse, nous avons développé de nouveaux algorithmes et architectures qui combinent les avantages des solutions proposées, tout en évitant leurs limitations. Les points abordés durant ce projet sont: 1) Proposer de nouvelles topologies, étudier leurs propriétés, leurs performances, ainsi que leurs coûts de construction. 2) Conception des algorithmes de routage et des modèles pour réduire la consommation d’énergie en prenant en considération la complexité, et la tolérance aux pannes. 3) Conception des protocoles et des systèmes de gestion de file d’attente pour fournir une bonne qualité de service. 4) Évaluation des nouveaux systèmes en les comparants à d’autres architectures et modèles dans des environnements réalistes. / The increasing trend to migrate applications, computation and storage into more robust systems leads to the emergence of mega data centers hosting tens of thousands of servers. As a result, designing a data center network that interconnects this massive number of servers, and providing efficient and fault-tolerant routing service are becoming an urgent need and a challenge that will be addressed in this thesis. Since this is a hot research topic, many solutions are proposed like adapting new interconnection technologies and new algorithms for data centers. However, many of these solutions generally suffer from performance problems, or can be quite costly. In addition, devoted efforts have not focused on quality of service and power efficiency on data center networks. So, in order to provide a novel solution that challenges the drawbacks of other researches and involves their advantages, we propose to develop new data center interconnection networks that aim to build a scalable, cost-effective, high performant and QoS-capable networking infrastructure. In addition, we suggest to implement power aware algorithms to make the network energy effective. Hence, we will particularly investigate the following issues: 1) Fixing architectural and topological properties of the new proposed data centers and evaluating their performances and capacities of providing robust systems under a faulty environment. 2) Proposing routing, load-balancing, fault-tolerance and power efficient algorithms to apply on our architectures and examining their complexity and how they satisfy the system requirements. 3) Integrating quality of service. 4) Comparing our proposed data centers and algorithms to existing solutions under a realistic environment. In this thesis, we investigate a quite challenging topic where we intend, first, to study the existing models, propose improvements and suggest new methodologies and algorithms.

Este trabalho propõe políticas para servidores Web baseados em sessões, visando ao oferecimento de garantias de qualidade de serviço (Quality of Service - QoS) a seus usuários. Para o fornecimento de QoS, dois tipos de políticas são consideradas: as responsáveis pela diferenciação de serviços e as responsáveis pelo controle de admissão. Alguns algoritmos de escalonamento foram desenvolvidos com o objetivo de oferecer melhores serviços para as sessões prioritárias: o algoritmo de escalonamento baseado em sessão (SBSA) e o algoritmo de escalonamento baseado em sessão com diferenciação de serviços (SBSA-DS). Quanto ao controle de admissão, foram consideradas duas novas políticas, as quais utilizam diferentes parâmetros para a tomada de decisão e têm como objetivo garantir a finalização do maior número de sessões prioritárias. A partir dos resultados obtidos nos experimentos realizados por meio de simulação, constatou-se que o emprego dos algoritmos e das políticas desenvolvidos melhora o atendimento das sessões para as quais deve ser oferecido um serviço preferencial. Portanto, em servidores Web preocupados com a garantia de QoS para seus usuários, os quais interagem com o sistema por meio de sessões, o uso dessas novas técnicas se mostra adequado / This work considers policies for Web servers based on sessions, aiming at the guarantees of Quality of Service (QoS) to the systems users. Two types of policies are considered: the responsible for the differentiation of services and the responsible for the admission control. Some scheduling algorithms had been developed to offer better services for the priority sessions: the Session Based Scheduling Algorithm (SBSA) and the Session Based Scheduling Algorithm with Differentiation of Services (SBSA-DS). In relation to the admission control, two new policies had been considered, which use different parameters to help the decisions and have as objective guarantee the finalization of as many priority sessions as possible. From the obtained results of the experiments realized by mean of simulation, it is evidenced that the use of the developed algorithms and policies improves the attendance of the sessions that deserve preferential service. Therefore, in Web servers worried in the guarantee the QoS for their users, which interact with the system by sessions, the use of these new techniques reveals adequate

Esta dissertação de mestrado apresenta o projeto, implementação e teste de um gerador de carga de trabalho para servidores Web que permite a caracterização de sessões e que representa uma carga real. O gerador desenvolvido gera carga visando à alimentar programas que simulam o comportamento de servidores Web. Para a definição dos parâmetros utilizados no gerador de carga sintética desenvolvido, diversos estudos sobre a carga em servidores Web encontrados na literatura, logs de servidores Web reais e benchmarks para servidores Web, foram utilizados. Vários algoritmos de controle de admissão e de escalonamento de requisições descritos na literatura foram implementados para teste e validação do gerador desenvolvido. Visando a utilização de sessões, é proposto nesta dissertação um algoritmo de controle de admissão, RED-SB (Random Early Detection - Session Based) que se baseia em um algoritmo (RED) que não considera sessão. Esses algoritmos foram executados utilizando-se um modelo de simulação de servidor Web com suporte a diferenciação de serviços, chamado SWDS (Servidor Web com Diferenciação de Serviços) / This MSc dissertation presents the design, implementation and tests of a workload generator for Web servers that allows the characterization of sessions and represents a real workload. The generator developed generates a workload to be used as an input to programs that simulate the behavior of Web servers. For the definition of the parameters used in the synthetic workload generator developed, several studies about the web server load described in the literature, actual web server logs and benchmarks for Web servers were used. Several algorithms for admission control and scheduling of requests described in the literature were implemented for testing and validation of the generator developed. Aiming at the utilization of sessions, this dissertation proposes an admission control algorithm RED-SB (Random Early Detection - Session based) which is based on an algorithm (RED) that does not consider session. These algorithms were implemented using a simulation model ofWeb server that supports service differentiation, called SWDS (Web Server with Service Differentiation)

Software Defined Networking (SDN) provides centralized control by separating the control plane from the data plane on network devices. Subareas of networking such as Quality of Service (QoS) can greatly benefit from this separation as QoS policies can be provided globally for the network. One way of providing QoS is to reserve and monitor network resources to guarantee a specific data rate for a requested transmission end-to-end. The presented thesis looks into possible ways of controlling the wireless medium using SDN to provide QoS. A method for providing QoS in a multihop SDN network supporting wired and wireless communication was implemented. The method was evaluated using network performance metrics such as throughput and packet jitter. The results of the experiments showed that the implemented method could limit bandwidth utilization and prioritize bandwidth usage for higher priority nodes. The performance of the network was concluded to have severe issues with dropped packets and irregular packet jitter spikes.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-10-08T14:58:45Z No. of bitstreams: 1 Rogério Inácio KnebeL_.pdf: 2220532 bytes, checksum: 0d612ed1de68a73a97697f38d176b2e9 (MD5) / Made available in DSpace on 2018-10-08T14:58:46Z (GMT). No. of bitstreams: 1 Rogério Inácio KnebeL_.pdf: 2220532 bytes, checksum: 0d612ed1de68a73a97697f38d176b2e9 (MD5) Previous issue date: 2018-06-27 / Nenhuma / O serviço no varejo se torna uma diferenciação quando o mesmo é percebido pelo consumidor, desta forma, agregando na sua experiência. A execução do serviço passa efetivamente pelos funcionários que desempenham a função de atendimento a este consumidor. Diante disto, este estudo tem como objetivo analisar a orientação para o serviço (OS) dos funcionários que fazem o atendimento dos consumidores e, em seguida, testar a influência da OS sobre a qualidade percebida do serviço do varejo e a experiência do consumidor. Foi realizada uma survey no varejo de lojas físicas (offline), sendo medida a OS a partir da avaliação dos funcionários (n=100), e a qualidade percebida e a experiência sob o ponto de vista dos consumidores (n=1.000). A técnica estatística adotada para análise dos dados foi a Modelagem de Equações Estruturais (MEE). Os resultados mostraram uma influência não significativa da orientação do serviço ao consumidor na qualidade percebida do serviço e na experiência do consumidor. / The retail service becomes distinctive when it is noticed by the customer, thus, adding up in his experience. The execution of the service actually relies on the employees who perform the assistance to this customer. Therefore, this study aims at analyzing the orientation to service (OS) of the employees who perform customers’ assistance and, then, testing the influence of the OS upon the quality of retail service perceived and the customer’s experience. Hence a survey was carried out in physical stores (offline), where the OS was measured through employees evaluation (n=100), also the quality perceived and the experience from the customer’s point of view (n=1000). The adopted statistic technique were: Structural Equation Modeling. Results showed a nonsignificant influence of employee service orientation on customers experience and quality of service perceived.

Este trabalho de mestrado apresenta a modelagem, a prototipação e os resultados do desenvolvimento de um middleware para composição dinâmica de Web Services denominado DWSC-M (Dynamic Web service Composition Middleware). O objetivo principal desse middleware é permitir que serviços sejam compostos dinamicamente considerando aspectos de qualidade de serviço na escolha dos serviços que fazem parte de um fluxo de composição. Para complementar o funcionamento do middleware DWSC-M foram propostos dois algoritmos para seleção de Web Services: o primeiro utiliza seleção aleatória e o segundo utiliza distância Euclidiana para seleção de serviços e considera, para tal finalidade, os parâmetros de QoS enviados pela requisição do cliente do serviço / This work presents the modeling, the prototype and the results of the developing of a middleware for dynamic composition of Web Services named DWSC-M (Dynamic Web Service Composition Middleware). The main focus of this middleware is to allow services being dynamically composed, considering aspects of quality of service in the choice of services that are part of the composite flow. Complementing the operation of the DWSC-M middleware two algorithms were proposed for Web Services selection : the first one uses Random selection and the second one uses Euclidean Distance for the selection of services and considers for this purpose the QoS parameters sent by the client service request