The Design And Implementation Of A P2P Media Distribution System Based On DHT In IPV6Environment

With the dramatically expanding of network size and number of users, Internet traffic has increased dramatically. It puts great pressure on the bandwidth of the network, the burden of server becomes,larger and larger. At the same time, the service is not stable. The C/S architecture network use center server to transmit and processing information. There will cause network congestion and performance bottlenecks. At the same time, the rapid development of the personal computer, making each computer has strong ability of computing and storage compared with the past. But the performance are not fully utilized in most cases. In P2P network, each node in the network is equality and independence. There are no central server. Nodes directly send information and data to other nodes. On the one hand, each node in network do part of work of center server, greatly reduce the server and network bandwidth pressure. At the same time, as a result of the P2P nodes distribution characteristics, the P2P network is robustness and expansibility. It can avoid the single point of failure; On the other hand, it also makes the untapped performance in the personal computer fully utilized. Since there is no central server, resource store in each node in the network. So the key problem is how to find nodes that store resources quickly in P2P networks. The first generation of P2P system is based on the directory server architecture, while resources are stored in the nodes. But it needs a directory server to record the location of specific resources. If a node wants to download a file, it shall communicate with the directory server to get file store information firstly. Then communicate with the node to obtain resources directly. With the number of users increasing, the directory server has performance bottle-neck problem. The second generation is unstructured architecture. It uses flood to find the file storage information in the network. With the network size growing, it will bring more traffic burden in the network. According to the problems above, there put forward the third generation of P2P network based on DHT. The file index information will be stored on each node in DHT network, replaced the directory server. If a node wants to download a file, it can use specific routing algorithm to find file index information quickly. And then directly communicate with nodes that store this file. Kademlia algorithm is currently applied widely, such as Chord、Pastry、CAN. At present, the DHT network base on Kademlia algorithm still exists many problems and needs to be improved. Firstly, the DHT which based on Kademlia don’t support IPv6network, and unable to work in pure IPv6network. Secondly, the logical and physical location of the nodes is not relevant in DHT network. It will reduce the routing lookup efficiency. All the nodes are equality in current DHT architecture. A node need to search resources from nodes in other domain. To solve above problems, we modify DHT to support pure IPv6network base on Libtorrent library. And then taking advantage of IPv6features the physical location information is corresponded to logical information at the same time. Finally, thought hierarchical optimization, the DHT network has better routing efficiency. With the improvements above, it designs and realizes a P2P media sharing system based on DHT in IPv6network environment and examines the effects of optimization scheme.