Measurement and Analysis of BitTorrent

The P2P content distribution, represented by BitTorrent, has become a popular P2P application. In BitTorrent, peers employ neighbor selection mechanism, choking/unchoking mechanism, and piece selection algorithm to get the required file rapidly. BitTorrent brings the users good downloading experience. However, it is strongly controversial in application. Most complaints come from the ISPs. BitTorrent is not highly efficient. Its fast downloading experience is at cost of network abuse. And this kind of misuse badly affects other Internet services supported by ISPs. An in-depth analysis from the perspective of techniques is demanded to understand the reasons why BitTorrent is popular with users and content providers, while complained by ISPs. Only if all the advantages and the disadvantages of BitTorrent are figured out, it is possible to design a better P2P content distribution protocol. From the perspective of performance, the behaviors of BitTorrent are measured, its key elements are explained, and its efficiency is analyzed. The results are as follows: 1） An effective way to measure the performance of P2P content distribution systems is proposed; 2） It is confirmed that BitTorrents key mechanisms, such as neighbor selection mechanism, choking/unchoking mechanism, and piece selection algorithm, is not highly efficient; and 3） A ShareStorm protocol is designed, which overcomes those flaws of BitTorrent. Preliminary experiment shows that in terms of download time, ShareStorm outperforms BitTorrent by 50%.