10 research outputs found

    Distributed admission control for QoS and SLS management

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    This article proposes a distributed admission control (AC) model based on on-line monitoring to manage the quality of Internet services and Service Level Specifications (SLSs) in class-based networks. The AC strategy covers intra- and interdomain operation, without adding significant complexity to the network control plane and involving only edge nodes. While ingress nodes perform implicit or explicit AC resorting to service-oriented rules for SLS and QoS parameters control, egress nodes collect service metrics providing them as inputs for AC. The end-to-end operation is viewed as a cumulative and repetitive process of AC and available service computation.We discuss crucial key points of the model implementation and evaluate its two main components: themonitoring process and the AC criteria. The results show that, using proper AC rules and safety margins, service commitments can be efficiently satisfied, and the simplicity and flexibility of the model can be explored to manage successfully QoS requirements of multiple Internet services.(undefined

    Optimal Partition of QoS Requirements on Unicast Paths and Multicast Trees

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    We investigate the problem of optimal resource allocation for end-to-end QoS requirements on unicast paths and multicast trees. Specifically, we consider a framework in which resource allocation is based on local QoS requirements at each network link, and associated with each link is a cost function that increases with the severity of the QoS requirement. Accordingly, the problem that we address is how to partition an end-to-end QoS requirement into local requirements, such that the overall cost is minimized. We establish efficient (polynomial) solutions for both unicast and multicast connections. These results provide the required foundations for the corresponding QoS routing schemes, which identify either paths or trees that lead to minimal overall cost. In addition, we show that our framework provides better tools for coping with other fundamental multicast problems, such as dynamic tree maintenance. Keywords --- QoS, QoS-dependent costs, Multicast, Routing, Broadband ne..

    Delay-aware Link Scheduling and Routing in Wireless Mesh Networks

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    Resource allocation is a critical task in computer networks because of their capital-intensive nature. In this thesis we apply operations research tools and technologies to model, solve and analyze resource allocation problems in computer networks with real-time traffic. We first study Wireless Mesh Networks, addressing the problem of link scheduling with end-to-end delay constraints. Exploiting results obtained with the Network Calculus framework, we formulate the problem as an integer non-linear optimization problem. We show that the feasibility of a link schedule does depend on the aggregation framework. We also address the problem of jointly solving the routing and link scheduling problem optimally, taking into account end-to-end delay guarantees. We provide guidelines and heuristics. As a second contribution, we propose a time division approach in CSMA MAC protocols in the context of 802.11 WLANs. By grouping wireless clients and scheduling time slots to these groups, not only the delay of packet transmission can be decreased, but also the goodput of multiple WLANs can be largely increased. Finally, we address a resource allocation problem in wired networks for guaranteed-delay traffic engineering. We formulate and solve the problem under different latency models. Global optimization let feasible schedules to be computed with instances where local resource allocation schemes would fail. We show that this is the case even with a case-study network, and at surprisingly low average loads

    A differentiated quality of service oriented multimedia multicast protocol

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    Les systèmes de communication multimédia modernes aspirent à fournir de nouveaux services tels que des communications multipoints. Néanmoins, l'apparition de dispositifs multimédias très diversifiés et le nombre croissant de clients ont révélé de nouveaux besoins pour les mécanismes et les protocoles. Dans une communication multimédia, les flux présentent des contraintes différentes et la QdS requise pour chaque flux n'est pas la même. De plus, dans une communication multipoint, tous les utilisateurs ne peuvent pas ou ne sont pas capables de recevoir la même QdS ; cette contrainte implique que les nouveaux mécanismes de communication doivent prendre en compte les besoins des utilisateurs pour fournir un service adéquat à chaque utilisateur, surtout pour éviter le gaspillage des ressources réseau. Cette thèse propose une architecture multipoint à QdS différentiée appelée M-FPTP. Basée sur des proxies client/serveur, elle relie plusieurs LANs multipoints à travers des liens point-à-point partiellement fiables. Cette architecture fournit une QdS différente à chaque LAN dépendant des besoins des utilisateurs. Pour ce faire, nous proposons un modèle du réseau appelé Arbre Hiérarchisé (AH) qui représente en même temps les performances du réseau et les contraintes de QdS des utilisateurs. Nonobstant, l'application de méthodes standard pour la création d'arbres sur un AH peut conduire à des problèmes de surcharge du degré de sortie dans la source. Pour résoudre ce problème, nous proposons alors un nouvel algorithme appelé Arbre de Plus Courts Chemins à Degré de Sortie Limité. Le déploiement de ce service nécessite, pour gérer les utilisateurs et le déploiement correct des proxies, un nouveau protocole appelé Protocole Simple de Session pour QdS multipoint. L'ensemble des solutions proposées a été modélisé, vérifié, validé et testé en utilisant UML 2.0 et l'outil TAU G2. ABSTRACT : Modern multimedia (MM) communication systems aim to provide new services such as multicast (MC) communication. But the rising of new very different MM capable devices and the growing number of clients drive to new requirements for mechanisms and protocols. In a MM communication, there are some flows that have constraints different from others and the required QoS for each flow is not the same. Furthermore, in MC communications, all the users do not want or are not able to receive the same QoS. These constraints imply that new communication mechanisms have to take into account the user requirements in order to provide an ad hoc service to each user and to avoid wasting the network resources. This dissertation proposes a new differentiated QoS multicast architecture, based on client/server proxies, called M-FPTP, which relays many MC LANs by single partially reliable links. This architecture provides a different QoS to each LAN depending on the users requirements. For doing so, it is also provided a network model called Hierarchized Graph (HG) which represents at the same time the network performances and the users QoS constraints. Nevertheless, the application of standard tree creation methods on an HG can lead to source overloading problems. It is then proposed a new algorithm called Degree-Bounded Shortest-Path-Tree (DgB-SPT) which solves this problem. However, the deployment of such a service needs a new protocol in order to collect users requirements and correctly deploy the proxies. This protocol is called Simple Session Protocol for QoS MC (SSP-QoM). The proposed solutions have been modeled, verified, validated and tested by using UML 2.0 and TAU G2 CASE tool
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