Research On File Sharing Technique Based On Peer-to-Peer

As Peer-to-Peer (P2P) applications are widely applied, the demand for P2P application model is also growing. Compared to traditional Client/Server (C/S) model, P2P is off-center, scalability, high performance-price ratio, strong robustness, load balancing, and so on. Thus, more and more organizations and persons are applying P2P technology into file sharing field. However, to be more influential in this field, P2P still has to be improved in some aspects such as resource search, data trasfer (NAT Traversal), the security and incentive mechanism.At present, the research of P2P search mainly focuses on the improvement of the existing unstructured search algorithm (e.g.: Flooding) and the study of new search algorithms. This thesis focuses on unstructured P2P search algorithm. Flooding will be studied in-depth to find out its inherent laws. Data transmission technology (NAT Traversal) is one of the key issues of P2P file-sharing system to be resolved. NAT mapping of the existing port facilities through the mechanism of research and analysis .This thesis proposes a software method to solve the probleme of Peer-to-Peer communiction across network address translators (NAT).At last, the principle, related protocols and some algorithms of BitTorrent are analysed and studied. And the result shows that the adjacent nodes randomly selection algorithm of BitTorrent can easily cause across-ISP traffic growth and network congestion. In addition, there are a lot of NATed nodes in BitTorrent network. They can not share data each other, because of NAT. In order to improve the performance of BitTorrent, this thesis proposes one new adjacent nodes selection algorithm and a software solution for NAT problem.