【作者】 李璐；

【导师】 张国印；

【作者基本信息】 哈尔滨工程大学 ， 计算机应用技术， 2011， 硕士

【摘要】 作为近年来互联网流行的通信技术,P2P所具有的非中心化、负载均衡、易扩展等优点,都使其突破了传统的C/S结构上所带来的限制,并在分布式计算、即时通信等方面获得了巨大的进展。由于内容分发性能一直作为网络发展的重要衡量标准,而如何提高P2P内容分发机制,使其在带宽利用率、网络吞吐量等实际问题中得到改善,是此领域的主要研究目的。本文的研究重点是将网络编码技术应用在P2P内容分发机制上,以此解决现有的-些如BT等P2P内容分发软件的现存问题。即首先提出利用分割法将大文件进行切割,对文件片段进行编码操作,小容量的编码包可以在有限的带宽中提高网络吞吐量,并降低传输延时。其次,文件片段作为传输的最小单位可以快速将资源分发到网络中,可以解决下载成功率完全依赖“种子”节点的在线时间和稳定性的情况。最后,经过编码区分开的编码包,可以使得节点之间通过另立信道来互相传输所缺信息块,从而解决了相同资源不断重复下载所浪费的时间、带宽的问题。因此,网络编码技术作为新兴技术一经提出,便得到此领域的高度重视和研究。在深入研究网络编码技术理论及实际应用方面为前提,本文选择随机线性网络编码算法,将其与P2P内容分发技术相结合,并通过Oversim仿真平台进行模拟,实验数据表明引入网络编码后的P2P内容分发机制,在各项性能上有了很大的提高,进而增强了系统的鲁棒性,改善了资源的下载速率和成功率。更多还原

【Abstract】 As a prevailing communication technology for the Internet in recent years, P2P possesses many advantages, such as decentralization, load balance, expandability, which help to break through the constraints that the traditional C/S structure had. Furthermore, PSP has achieved great progress in distributed computing and instant communications. Content distribution as an important criterion for the development of network performance, how to improve the P2P content distribution mechanism so as to solve practical problems such as bandwidth utilization and network throughput is the primary purpose in the relevant field.In the P2P content distribution mechanism, how to use the network coding technology is the key research field. In this way, the problems that exist in the P2P content distribution software such as BT can be solved. Firstly, cut the large files into small pieces by segmentation method and encode the small file pieces. The encoding packets with small capacity can improve the network throughput in the limited bandwidth and reduce the transmission delay. Secondly, the file pieces as the smallest unit in the transmission can be distributed to the network quickly. In this way, the problem that the download success rate entirely depends on the online time and stability of seeds nodes can be solved. Lastly, the encoded packets divided in the coding area can be transmitted among the other nodes through new channels, so the nodes can acquire the information blocks that have not downloaded from the other nodes but not from the encoding area. The waste of time and download bandwidth due to repetitive downloading of the same resources can be solved.So, network coding technology as a new technology, once put forward, has attracted attention and provoked research in the field. After the research on network coding technology in theory and practice, this paper adopts the random linear network coding algorithm, which is combined with P2P content distribution technology. The experiment data obtained from the OverSim simulation platform show that the performance in the P2P content distribution mechanism combined with the network encoding technology can be enhanced. The robustness of the system, the resource download rate and success rate can be greatly improved, too.更多还原