| Summary: | 碩士 === 國立清華大學 === 資訊工程學系 === 93 === DHT-based structured P2P networks could not support complex queries, such as range query and wild-card matching, due to their reliance on hashing to name the objects to be managed. A workaround is to broadcast the query to all nodes in the network, where the query can be processed locally. Previous research has suggested to build a spanning tree on a structured P2P network using local routing information. Once the spanning tree is built, queries can be propagated upon it without redundancy. Yet it has not been studied on how to broadcast to a limited scope effectively and efficiently instead of to the whole network. By a scope, we mean a broadcast message is sent to all nodes in a region in the overlay network defined by the scope and centered on the sender. A k-node scoped broadcast is a scoped broadcast that reaches at least k nodes. One way to control the broadcast scope is to set a TTL value. Because of the dynamic nature of P2P networks, the spanning tree changes continuously. Thus the value of TTL must be chosen carefully to achieve different scoped broadcast requirements. The goal of this thesis is to investigate and evaluate ways of selecting TTL values for k-node scoped broadcast in DHT-based P2P networks. We discuss three possible solutions. The main idea of these methods is that network exploration should be performed before broadcast, and the explored information could be used to pick a suitable TTL value for scope k. We evaluate our approaches through simulations. It is showed that with network density information, scoped broadcast could be performed more efficiently.
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