科研之友
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摘要
Despite strong interest in peer-to-peer (P2P) Video-on-Demand (VoD) services, existing studies mostly focus on peer-to-peer or overlay protocol design based on simulations under various topological constraints. We believe experimental studies on a real-life P2P VoD system will provide valuable information to ISPs, network administrators, and content owners. In this paper we present a comprehensive analytical and experimental study on Joost, one of the first commercial P2P VoD systems used for distributing various forms of video over the Internet. Our extensive experiments prove that Joost is a server-assisted peer-to-peer VoD system. With several envisioned typical scenarios we have further investigated the peer management in terms of time pattern, bandwidth consumption and locality considerations. Our major findings include: (1) the current Joost system is capable of providing high-quality VoD service through the use of an overlay network deployed with a set of centralized content servers; (2) inter-continental links are often used regardless of the number of local users, which may pose a high burden on the network providers; (3) easily reachable, high-capacity nodes are selected as main relaying nodes, similar to super nodes in Skype, to facilitate the traversal of symmetric NATs and firewalls. We also provide insights on the potential ways to construct more efficient P2P VoD systems (e.g. considering topological locality-awareness, using adaptive/layered video).
- 出版日期2010-12
