Packet and flow level simulations of BitTorrent-like P2P networks

Peer-to-Peer (P2P) networks can reduce the distribution cost of large media files for the original provider of the data significantly. Thereby, the BitTorrent protocol is widely used in the Internet today. Most research work studies the protocol analytically, by simulations at the flow-level or real world experiments. For flow-level simulations the influence of neglecting packet-level characteristics (e.g. TCP) is not yet quantified. Therefore, this paper compares packet-level simulation results with flow-level values and analytically derived bounds. Our findings show that BitTorrent is near to optimal at flow-level for different scenarios. Naturally, packet-level results deviate more from the optimal values but differences are at most around 30% in our simulations. Furthermore, we show that the propagation delay can significantly influence the peer selection in BitTorrent and the download performance of the peers. Hence, the unchoking/choking algorithm in BitTorrent exploits implicitly network proximity.

[1]  Sally Floyd,et al.  Promoting the use of end-to-end congestion control in the Internet , 1999, TNET.

[2]  B. Cohen,et al.  Incentives Build Robustness in Bit-Torrent , 2003 .

[3]  Tobias Hoßfeld,et al.  Towards Efficient Simulation of Large Scale P2P Networks , 2005 .

[4]  Tobias Hoßfeld,et al.  Efficient simulation of large-scale p2p networks: packet-level vs. flow-level simulations , 2007, UPGRADE '07.

[5]  Eddie Kohler,et al.  Clustering and sharing incentives in BitTorrent systems , 2006, SIGMETRICS '07.

[6]  Rayadurgam Srikant,et al.  Modeling and performance analysis of BitTorrent-like peer-to-peer networks , 2004, SIGCOMM 2004.

[7]  Venkata N. Padmanabhan,et al.  Analyzing and Improving BitTorrent Performance , 2005 .

[8]  Qi He,et al.  Mapping peer behavior to packet-level details: a framework for packet-level simulation of peer-to-peer systems , 2003, 11th IEEE/ACM International Symposium on Modeling, Analysis and Simulation of Computer Telecommunications Systems, 2003. MASCOTS 2003..

[9]  Tobias Hoßfeld,et al.  Efficient Simulation of Large-Scale P2P Networks: Compact Data Structures , 2007, 15th EUROMICRO International Conference on Parallel, Distributed and Network-Based Processing (PDP'07).

[10]  Tobias Hoßfeld,et al.  Efficient Simulation of Large-Scale P2P Networks: Modeling Network Transmission Times , 2007, 15th EUROMICRO International Conference on Parallel, Distributed and Network-Based Processing (PDP'07).

[11]  Eytan Adar,et al.  Free Riding on Gnutella , 2000, First Monday.

[12]  Mikel Izal,et al.  Dissecting BitTorrent: Five Months in a Torrent's Lifetime , 2004, PAM.

[13]  Odlyzko Andrew.  Data Networks are Lightly Utilized, and Will Stay That Way , 1999 .

[14]  Gustavo de Veciana,et al.  Performance of peer-to-peer networks: Service capacity and role of resource sharing policies , 2006, Perform. Evaluation.

[15]  Ulrich Killat,et al.  Bandwidth Trading in Unstructured P2P Content Distribution Networks , 2006, Sixth IEEE International Conference on Peer-to-Peer Computing (P2P'06).