O objetivo desta dissertação é avaliar o desempenho de ambientes virtuais de roteamento construídos sobre máquinas x86 e dispositivos de rede existentes na Internet atual. Entre as plataformas de virtualização mais utilizadas, deseja-se identificar quem melhor atende aos requisitos de um ambiente virtual de roteamento para permitir a programação do núcleo de redes de produção. As plataformas de virtualização Xen e KVM foram instaladas em servidores x86 modernos de grande capacidade, e comparadas quanto a eficiência, flexibilidade e capacidade de isolamento entre as redes, que são os requisitos para o bom desempenho de uma rede virtual. Os resultados obtidos nos testes mostram que, apesar de ser uma plataforma de virtualização completa, o KVM possui desempenho melhor que o do Xen no encaminhamento e roteamento de pacotes, quando o VIRTIO é utilizado. Além disso, apenas o Xen apresentou problemas de isolamento entre redes virtuais. Também avaliamos o efeito da arquitetura NUMA, muito comum em servidores x86 modernos, sobre o desempenho das VMs quando muita memória e núcleos de processamento são alocados nelas. A análise dos resultados mostra que o desempenho das operações de Entrada e Saída (E/S) de rede pode ser comprometido, caso as quantidades de memória e CPU virtuais alocadas para a VM não respeitem o tamanho dos nós NUMA existentes no hardware. Por último, estudamos o OpenFlow. Ele permite que redes sejam segmentadas em roteadores, comutadores e em máquinas x86 para que ambientes virtuais de roteamento com lógicas de encaminhamento diferentes possam ser criados. Verificamos que ao ser instalado com o Xen e com o KVM, ele possibilita a migração de redes virtuais entre diferentes nós físicos, sem que ocorram interrupções nos fluxos de dados, além de permitir que o desempenho do encaminhamento de pacotes nas redes virtuais criadas seja aumentado. Assim, foi possível programar o núcleo da rede para implementar alternativas ao protocolo IP. / The aim of this work is to evaluate the performance of routing virtual environments built on x86 machines and network devices existing on the Internet today. Among the most widely used virtualization platforms, we want to identify which best meets the requirements of a virtual routing to allow programming of the core production networks. Virtualization platforms Xen and KVM were installed on modern large capacity x86 machines, and they were compared for efficiency, flexibility and isolation between networks, which are the requirements for good performance of a virtual network. The tests results show that, despite being a full virtualization platform, KVM has better performance than Xen in forwarding and routing packets when the VIRTIO is used. Furthermore, only Xen had isolation problems between networks. We also evaluate the effect of the NUMA architecture, very common in modern x86 servers, on the performance of VMs when lots of memory and processor cores are allocated to them. The results show that Input and Output (I/O) network performance can be compromised whether the amounts of virtual memory and CPU allocated to VM do not respect the size of the existing hardware NUMA nodes. Finally, we study the OpenFlow. It allows slicing networks into routers, switches and x86 machines to create virtual environments with different routing forwarding rules. We found that, when installed with Xen and KVM, it enables the migration of virtual networks among different physical nodes, without interruptions in the data streams, and allows to increase the performance of packet forwarding in the virtual networks created. Thus, it was possible to program the core network to implement alternatives to IP protocol.

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Die politische Öffnung der Welt, die Deregulierung der Märkte sowie die informationstechnischen Möglichkeiten zur Restrukturierung von Unternehmungen werden begleitet von einer zunehmenden Verbreitung entstandardisierter Beschäftigungsverhältnisse und dem Rückgang klassischer Erwerbsbiographien (vgl. Weber 2005). Sie bilden den Nährboden für die Entstehung flexibler Modelle nicht-klassischer Organisations- und Arbeitsformen. Ein Beispiel hierfür ist die zunehmende Freisetzung hoch qualifizierter freiberuflicher Wissensarbeiter, die in Branchen wie IT- und Management-Beratung oder Personal- und Organisationsentwicklung tätig sind und sich in selbstorganisierten Netzwerken zusammenschließen. Eine bessere Außendarstellung und günstigere Bedingungen zur Auftragsakquise einerseits, sowie die Möglichkeit zur Bearbeitung komplexer kurzfristig personalintensiver Projekte, zu Fortbildungen, zu beruflichem und persönlichem Austausch andererseits, sind häufig genannte Vorteile, die ein Zusammenschluss im Netzwerk bieten kann.

Cette recherche traite du devenir de l’espace urbain et de ses logiques traditionnelles, dans un contexte marqué par les technologies de l’information et de la communication (TIC). Ce sujet est abordé par le prisme des commerces ethniques situés dans trois localités, parisiennes et régionales. Le regard est focalisé sur ces lieux afin de comprendre les facteurs à l’origine de la présence, en leur sein, des TIC accessibles au public. Trois hypothèses sont proposées. Il s’agit d’abord d’expliquer ce phénomène par le message des scénographies commerciales, puis par le besoin qu’éprouvent les migrants de maintenir les liens avec leurs origines culturelles et leur famille, enfin par l’appartenance des commerçants à la communauté des migrants. La méthodologie privilégie les méthodes d’enquête qualitative relevant de l’anthropologie et de la microsociologie. L’analyse des données permet de valider les hypothèses. Elle offre également la possibilité de montrer que dans une société marquée par les technologies de l’information et de la communication l’espace ne disparait pas sous le coup de la domination d’un espace en réseaux. Au contraire, l’analyse permet de souligner d’une part que l’espace urbain, avec ses logiques traditionnelles, persistent tout en s’articulant à une logique en réseaux. D’autre part, elle fait émerger la production de diverses formes spatiales. La plus significative offre à la principale clientèle la possibilité quotidienne de conserver son ancrage aux lieux urbains, tout en étant mobile et virtuellement mobile, de sortir des termes de la fracture numérique. Cette clientèle s’en trouve intégrée à la société en réseaux, dépasse la situation de double présence au pays d’origine et à la famille s’y trouvant et connaît des situations de multiples présences. Enfin, la recherche a permis de montrer que les lieux urbains et particulièrement les commerces ethniques sont des espaces de socialisation des réseaux virtuels en les situant au même niveau que les offres et services marchands, et qu’ils sont des outils dont les migrants et leur famille située à l’étranger savent se saisir pour permettre une évolution de leurs situations quotidienne et projets. / This research deals with the future of the urban space in a context marked by the Technologies of Information and Communication (ICT). This subject is approached by the prism of the ethnic businesses situated in three localities, Parisian and regional. The outlook is focused on these places to understand why ICT are included in those spaces open to the public.Three hypotheses are suggested. First, The ICT are included in the businesses thanks to the commercial message diffused through the setting up of goods. Then, the networking of businesses can be explained by the need which the migrants have to maintain the links with their cultural origins and their family, lastly through the membership of the storekeepers in the community of the migrants.The methodology favors the methods of qualitative investigation coming from the anthropology and the micro-sociology. The empirical data allows a validation of the hypotheses. The analysis of those data underline first that, in the network society, urban places don’t disappear. Among them, the ethnic shops are areas of socialization of the virtual networks by placing them at the same level as the offers of the goods and the trade services. Then, the space produced by those businesses offers to the main clientele the possibility of preserving its anchoring in the urban places while being mobile and virtually mobile. By this last idea, this research shows that the ethnic business and ICT are articulated tools which the migrants and their family situated abroad know how to seize to allow an evolution of their daily situations and projects. This analysis gives possibility to considered migrants out terms of the digital divide, and as integrated into the networks society. This new figure of migrant has overtaken the situation of double presence in their origin country and to their family living there, to actually know situations of multiple presences in this country and to their relatives.