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Sun Y.,CAS Institute of Computing Technology | Yang Y.R.,Yale University | Zhang X.,Shanghai Synacast Media Technology Co. | Guo Y.,CAS Institute of Computing Technology | And 2 more authors.
IEEE Journal on Selected Areas in Communications | Year: 2013

P2P platforms have been criticized because of the heavy strain that they can inflict on costly inter-domain links of network operators. It is therefore mandatory to develop network optimization schemes for controlling the load generated by a P2P platform on an operator network. While many research efforts exist on centralized tracker-based systems, in recent years multiple DHT-based P2P platforms have been widely deployed and considered as commercial services due to their scalability and fault tolerance. Finding network optimization for DHT-based P2P applications has thereby potential large practical impacts. In this paper, we present THash, a simple scheme that implements a distributed and effective network optimization for DHT systems. THash uses standard DHT put/get semantics and utilizes a triple hash method to guide the DHT clients to choose their sharing peers in proper domains. We have implemented THash in a major commercial P2P system (PPLive), using the standard ALTO/P4P protocol as the network information source. We conducted experiments over this network in real operation and observed that compared with Native DHT, THash reduced respectively by 47.4% and 67.7% the inter-PID and inter-AS traffic, while reducing the average downloading time by 14.6% to 24.5%. © 1983-2012 IEEE.


Huang Y.,Shanghai SynaCast Media Technology Co. | Xu K.,Tsinghua University | Li H.,Tsinghua University | Cao Y.,Shanghai SynaCast Media Technology Co. | Yao X.,Shanghai SynaCast Media Technology Co.
Science China Information Sciences | Year: 2011

Using P2P network to provide video on demand (VOD) service can support large-scale users so as to save the bandwidth cost of servers. As VOD must support VCR characters (drag, pause, randomly choosing watching position, etc.), building a large-scale expansion of high-performance VOD system still faces huge challenges. The paper first presents a P2P based reference model, defines the design object, and analyzes the difficulties. And then taking PPLive demand system as an example, it gives client-based solutions, including disk cache-out strategy, memory cache prefetch strategy, maintaining relations between neighbors, task scheduling, data upload strategies and so on. PPLive-demand systems are putting into practice at present with satisfactory fluency and drag delay. The largest number of simultaneous online users is over 210000, and online video data is over 700. Compared with traditional client-server model, the average bandwidth saving rate of servers is 88% or more, and the bandwidth saving rate of user-number's the peak value can be up to 93%. © 2011 Science China Press and Springer-Verlag Berlin Heidelberg.


Deng G.-Q.,Beijing Jiaotong University | Wei T.,Beijing Jiaotong University | Chen C.-J.,Beijing Jiaotong University | Zhu W.,Shanghai SynaCast Media Technology Company Ltd | And 2 more authors.
Beijing Youdian Daxue Xuebao/Journal of Beijing University of Posts and Telecommunications | Year: 2012

To analyze the influence of the dynamics of download speed on performance of peer to peer (P2P) video on demand (VoD) streaming systems, a playback interruption model is presented. The model shows that the dynamics of download speed is the main reason of the playback interruption. Both increasing the prefetched content and the download speed can reduce the number of interruptions. However, the former delays the interruption, the latter brings forward the interruption. The interruption may happen frequently in the whole playback process, though with low probability. Through network measurement towards PPLive VoD system, the behavior of the interruption can be verified.

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