This paper presents and evaluates Toast, a scalable Video-on-Demand (VoD) streaming system that combines the popular Bit-Torrent peer-to-peer (P2P) file-transfer technology with a simple dedicated streaming server to decrease server load and increase client transfer speed. Toast includes a modified version of BitTorrent that supports streaming data delivery and that communicates with a VoD server when the desired data cannot be delivered in real-time by other peers. The results show that the

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... ault BitTorrent download strategy is not well-suited to the VoD environment because it fetches pieces of the desired video from other peers without regard to when those pieces will actually be needed by the media viewer. Instead, strategies should favor downloading pieces of content that will be needed earlier, decreasing the chances that the clients will be forced to get the data directly from the VoD server. Such strategies allow Toast to operate much more efficiently than simple unicast distribution, reducing data transfer demands by up to 70-90% if clients remain in the system as seeds after viewing their content. Toast thus extends the aggregate throughput capability of a VoD service, offloading work from the server onto the P2P network in a scalable and demand-driven fashion.