Architecture and download behavior of Xunlei:A measurement-based study

This paper presents a measurement-based study of Xunlei, a young but increasingly popular P2P application currently mainly used in China. Due to its proprietary protocols and data encryption, packet-level data was analyzed in order to infer the network architecture and the superior download behavior, Xunlei's main key to success. We identify Xunlei's core-server layer with a clear division of tasks. We found that Xunlei increases download speeds by applying multi-source technology in an effective way, which includes (inappropriate) direct linking. Finally, we reveal that Xunlei utilizes UDP as main transport protocol both for bulk file transfer and IPTV streaming. As the first comprehensive study on Xunlei, this paper provides new insights for researchers and application designers, and contributes to a better understanding of the Internet.