Abstract
There are two major building blocks in operating a peer-to-peer (P2P) video-on-demand (VOD) network: supplier discovery and content delivery. Supplier discovery concerns the discovery of peer nodes in the network that can provide the streaming data blocks needed for playing by a local node. The more suppliers one can discover, the higher the chance of locating quality suppliers for delivering contents smoothly to ensure uninterrupted playback. The key to supplier discovery is to establish and track the supply-demand relationship among the peers. For P2P VOD, the supply-demand relationship is determined by the buffer contents of the peers. Unfortunately, the buffer contents change rapidly as peers play the video, especially under VCR operations. The challenge is to track all the dynamic relationships in an efficient way. To achieve better supplier discovery, first we propose an Overlapping Relation Network (ORN). The idea is to track the dynamic supply-demand relationship by tracking the overlapping of peers' buffer contents. Once such overlapping relations are maintained, peers can be linked with their suppliers as overlay neighbors. When a new peer joins the system or a peer changes its demand and requires different contents, it can traverse via these overlay links to locate new suppliers quickly. Extensive analyses and simulation experiments show that in most cases ORN can discover more than 96% of the suppliers in the network, resulting in a streaming continuity superior to other approaches. Though the high discovery performance, ORN is not economic in term of maintenance cost. ORN requires each peer to discover and track all the eligible suppliers, even if the amount of suppliers is beyond the demander’s need. In this thesis, we also propose an adaptive method extended from ORN: the Throttle. In Throttle, the overlay neighbors that a peer should maintain are only a subset of that in ORN. Therefore, a Throttle peer incurs fewer maintenance costs and only needs to link to relatively fewer suppliers. Whenever needed, it can crawl upon the overlay to collect more suppliers. With a careful design of the neighbor selection rule, it is guaranteed that such crawling process can return as many suppliers as in ORN in a deterministic manner. In summary, Throttle is able to achieve full discovery as ORN, but can also discover peers incrementally by trading of communication costs. In ORN, the maintenance overhead grows as the system size increases. On the contrary, Throttle incurs constant overhead, which is independent of the system size. Analyses and simulation experiments have confirmed this property and the good scalability of Throttle in large systems.