A survey of BitTorrent study

1. A survey of BitTorrent study Jian Liang EL933 Prof. Yong Liu

2. Surveyed paper • Service Capacity of Peer to Peer Networks (INFOCOM 2004) X. Yang, G. Veciana • Modeling and Performance Analysis of Bit Torrent-Like Peer-to-Peer Networks (SIGCOMM 04) D. Qiu, R. Srikant • The Bittorrent P2P File-sharing System: Measurements and Analysis (IPTPS 2005) J. Pouwelse, P.Garbacki, D. Epema, H. Sips • Measurements, Analysis, and Modeling of BitTorrent-like Systems (IMC 2005) L. Guo, S. Chen, Z. Xiao, E. Tan, X. Ding, and X. Zhang • Analyzing and Improving BitTorrent Performance (INFOCOM 2006) A. Bharambe, C. Herley and V Padmanabhan

3. Outline • Overview of BitTorrent • Research interests covered • Methodology on BT study • Compare of these 5 papers • Interesting facts reflected in these works • Argument • Current development of BitTorrent

4. Tracker Web Server Web page with link to .torrent .torrent C A Peer [Seed] Peer [Leech] Downloader “US” B Peer [Leech] Overview – system components

5. Tracker Web Server Web page with link to .torrent Get-announce C A Peer [Seed] Peer [Leech] Downloader “US” B Peer [Leech] Overview – system components

6. Tracker Web Server Web page with link to .torrent Response-peer list C A Peer [Seed] Peer [Leech] Downloader “US” B Peer [Leech] Overview – system components

7. Tracker Web Server Web page with link to .torrent Shake-hand C A Peer [Seed] Peer [Leech] Downloader “US” Shake-hand B Peer [Leech] Overview – system components

8. Tracker Web Server Web page with link to .torrent pieces C A pieces Peer [Seed] Peer [Leech] Downloader “US” B Peer [Leech] Overview – system components

9. Tracker Web Server Web page with link to .torrent pieces C A pieces Peer [Seed] Peer [Leech] Downloader “US” pieces B Peer [Leech] Overview – system components

10. Tracker Web Server Web page with link to .torrent Get-announce Response-peer list pieces C A pieces Peer [Seed] Peer [Leech] Downloader “US” pieces B Peer [Leech] Overview – system components

11. Overview – BT features • Temporal one torrent community (no across torrents communication). • File/pieces/blocks. Content trade is piece based, while transfer is block based. Partial pieces can not be uploaded.

12. Overview – BT features • Peer selection- Fit-for-Tat (download speed based) “Interest”/”chock”/”unchock” • Piece selection - Local Rarest First (not global rarest)

13. Outline • Overview of BitTorrent • Research interests covered • Methodology on BT study • Compare of these 5 papers • Interesting facts reflected in these works • Argument • Current development of BitTorrent

14. Research focus • Generic network performance • Traffic volume, download/upload throughput, uplink utilization, peer behavior, service capacity, • Incentives • Fairness, peer game • Robustness • Website availability, peer workload, content integrity. • Limitation and improvement

15. Outline • Overview of BitTorrent • Research interests covered • Methodology on BT study • Compare of these 5 papers • Interesting facts reflected in these works • Argument of their works • Current development of BitTorrent

16. Methodology • Passive ways • (tracker log, torrent website monitor, traffic capture) • Active ways • Join the BT network to monitor peer performance • Simulation • Modeling

17. Outline • Overview of BitTorrent • Research interests covered • Methodology on BT study • Compare of these 5 papers • Interesting facts reflected in these works • Argument of their works • Current development of BitTorrent

18. Paper Method Data set Research Differentiation YV_INFOCOM04 Model + Trace Trace log of 150-200 torrents trackers Service capacity, scalability of flash crowd QS_SIGCOMM04 Model + simulation + little trace 3 days trace from one torrent tracker User evolution, peer game PG_IPTPS05 Trace 8 months trace from website, peer traffic and tracker Torrent website availability, content integrity GCXTDZ_IMC05 Trace + model 48 days tracker trace and 10 days ISP traffic (50 tracker sites and 3k peers) Performance across multi-torrents, BT limitation found from traces. BHP_INFOCOM06 Comprehensive simulation None Fairness, uplink utilization, improvement Compare of these five works

19. Outline • Overview of BitTorrent • Research interests covered • Methodology on BT study • Compare of these 5 papers • Interesting facts reflected in these works • Argument • Current development of BitTorrent

20. Interesting results • YV_INFOCOM04 • Exponential growth of service capacity in initial flash crowd • For less popular torrent (<50 peers), the performance is quite unpredictable

21. Interesting results • QS_SIGCOMM04 • Purpose a good BT fluid model and matches their simulation result well. • No surprising results yet.

22. Interesting results • PG_IPTPS05 • The arrival processes of peers are not Poisson assumed by SIGCOMM04 paper. • Power law relationship btw peer speed and # peers

23. Interesting results • PG_IPTPS05 • The availability of centralized supporting system is bad • # of seeds after 10 days is not accurate predictor for content life time, one single seed can be up for long period of time.

24. Interesting results • PGES_IPTPS05 • Centralized moderation seems very effective in removing fake and corrupted files. 5k of 8k torrent uploaded by 20 moderators daily. • Donated resource for meta-data entail integrity and privacy risks without control.

25. Interesting results • GCXTDZ_IMC05 • Exponentially decreasing peer arrival rate, lack of seeds make service availability poor quickly after flash crowd. • The leecher download speed at different time stages is highly diverse.

26. Interesting results • GCXTDZ_IMC05 • BT can provide unfair services. Peer contribution ratio decrease with its downloading speed increase. • The probability for a peer to abort downloading voluntarily is independent of its speed and downloading progress.

27. Interesting results • GCXTDZ_IMC05 • The life spans of torrent is btw 30-300 hours with average 8.5 days; average population of a torrent is only about 102 peers. • Seeding time is average as 8.42 hours

28. Interesting results • BHP_INFOCOM06 • The uplink utilization close to 100% • Workload of seeds increase slowly during flash crowd

29. Interesting results • BHP_INFOCOM06 • Single seed utilization outperforms that of multi-seeds • The more concurrent upload, the less uplink utilization

30. Interesting results • BHP_INFOCOM06 • For low bandwidth peers with small neighbors, random block exchange outperform LRF • But LRF outperform random block exchange in term of # interesting connections

31. Interesting results • BHP_INFOCOM06 • Block-level TFT outperform download speed based TFT in term of fairness • Quick BW estimation help archive optimal utilization

32. Interesting results • BHP_INFOCOM06 • Bandwidth-matching tracker policy further improve both utilization and fairness

33. Outline • Overview of BitTorrent • Research interests covered • Methodology on BT study • Compare of these 5 papers • Interesting facts reflected in these works • Argument • Current development of BitTorrent

34. Argument • INFOCOM06 : • the simulation does not consider user control of their uplink/downlink (BitComet enable uplink speed limits) • Tradeoff of the improvement ideas • Bandwidth measure overhead is ignored • Bandwidth clustering helps but is that violation of Internet ethics by separating different capable users?

35. Outline • Overview of BitTorrent • Research interests covered • Methodology on BT study • Compare of these 5 papers • Interesting facts reflected in these works • Argument • Current development of BitTorrent

36. Current BT development • DHT enabled peer search (BitComet, Bitsprite) • Decentralized torrent search (eXeem) • BT like Content delivery system (VOD, IPTV)