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Jussara Marques de AlmeidaAlex Borges VieiraAlex Borges VieiraItalo Fernando Scota CunhaSergio Vale Aguiar CamposAna Paula Couto da SilvaGlauber Dias Gonçalves2019-08-10T21:58:16Z2019-08-10T21:58:16Z2012-07-13http://hdl.handle.net/1843/ESBF-8XFMPAA arquitetura P2P vem sendo utilizada com sucesso para diminuir os custos e aumentar a escalabilidade dos sistemas de distribuição de vídeo ao vivo pela Internet, mas a eficácia desses sistemas depende muito do nível de cooperação dos seus participantes (pares). Neste trabalho, investiga-se o potencial de explorar propriedades topológicas da rede P2P sobreposta para prever o nível de cooperação de um par, medido pela razão entre as taxas de upload e download, durante uma janela de tempo pré-estabelecida. A partir de dados coletados do SopCast, mostra-se que métricas de centralidade provêem boas evidências sobre esse nível. Assim, foram desenvolvidos e avaliados modelos baseados em regressão para predizer, com precisão razoável, o nível de cooperação de um par no futuro próximo, dada a sua centralidade no passado recente. As propriedades topológicas da rede sobreposta ainda foram exploradas para a detecção de pares maliciosos que agem em conluio para aumentar a sua centralidade.P2P architecture has been used successfully to reduce costs and increase scalability of Internet live streaming systems. In a P2P live broadcast, users (peers) exchange video chunks to each other and cooperate for the system to distribute the media content. To measure peer\\\'s cooperation, these systems use only upload and download rates collected periodically from peers. However, such measures may be susceptible to malicious peers lie about their cooperation, which is a problem for incentive mechanisms that provide level of quality of service according to peer\\\'s cooperation. In this work, we investigate alternative methods to obtain peers\\\' cooperation without relying specifically on the their upload and download rates. In particular,we assess the potential benefit of exploiting topological properties of P2P overlay network to predict, with reasonable accuracy, peer\\\'s cooperation.Our study relies on data collected from one of the currently most popular P2P live applications, i.e., SopCast, using a large number of PlanetLab machines. It encompasses two main steps. We first show that centrality metrics are reasonably strongly correlated with the peer\\\'s cooperation level, which is defined by the ratio of the total upload to the total download traffic the peer exchanged with its partners. Moreover, we also show that a peer\\\'s centrality remains reasonably stable over consecutive time windows. Motivated by these findings, we then develop a regression-based model to predict the level of cooperation of a peer in the following time windows given its centrality measures collected in the last window. Using our collected data, we show that our approach can produce reasonably accurate predictions.We still exploit topological properties to enable the detection of malicious peers which collud to increase their cooperation level and receive benefits from the system improperly. In this case, we investigate the use of the metric conductance and analyze scenarios where this metric can be useful, besides, its advantages and limitations related to other approaches.Universidade Federal de Minas GeraisUFMGSistemas de transmissão de dadosComputaçãoVideodigitalTopologiaIPTVCentralidadeIncentivoP2PPredição do nível de cooperação em sistemas par-a-par de vídeo ao vivo a partir de métricas de centralidadeinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisinfo:eu-repo/semantics/openAccessporreponame:Repositório Institucional da UFMGinstname:Universidade Federal de Minas Gerais (UFMG)instacron:UFMGORIGINALglauberdiasgon_alves.pdfapplication/pdf6316339https://repositorio.ufmg.br/bitstream/1843/ESBF-8XFMPA/1/glauberdiasgon_alves.pdfe138f9dc90f17b1da35afe63bd17f46fMD51TEXTglauberdiasgon_alves.pdf.txtglauberdiasgon_alves.pdf.txtExtracted texttext/plain177068https://repositorio.ufmg.br/bitstream/1843/ESBF-8XFMPA/2/glauberdiasgon_alves.pdf.txt6a19814981a31038e1db515c0d006bc8MD521843/ESBF-8XFMPA2019-11-14 11:24:56.201oai:repositorio.ufmg.br:1843/ESBF-8XFMPARepositório InstitucionalPUBhttps://repositorio.ufmg.br/oaiopendoar:2019-11-14T14:24:56Repositório Institucional da UFMG - Universidade Federal de Minas Gerais (UFMG)false
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