1. Public and private BitTorrent communities: A measurement study M. Meulpolder, L. D’Acunto, M. Capotă, M. Wojciechowski, J.A. Pouwelse, D.H.J. Epema, H.J. Sips TU Delft

2. 2 /16 BitTorrent communities Content discovery web pages Communities User accounts Comments Ratings Forums Public and private

3. 3 /16 Motivation and goal Private communities employ more incentives Are there differences between public and private? Download speed Connectability Seeding duration Seeder/leecher ratio Fraction of bytes from seeders

4. 4 /16 Contents BitTorrent communities Motivation and goal Experimental setup Measurement results Conclusions

6. 6 /16

7. 7 /16 Experimental setup

8. 8 /16 Measurement details Time - September to December 2009 508 269 users 444 swarms Over 20 million bitfields

9. 9 /16 Download speed

10. 10 /16 Download speed Vs. previous results Guo, IMC 2005, public 160 kbit/s mean Pouwelse, IPTPS 2005, public 240 kbit/s mean 4 x higher overall mean 36 x higher PolishTracker mean

11. 11 /16 Connectability

12. 12 /16 Connectability Vs. previous results Pouwelse, IPTPS 2005 40% overall, same as today 2 x lower PolishTracker mean Mol, P2P 2008 66% for ThePirateBay 45% for TVTorrents

13. 13 /16 Seeders and leechers

14. 14 /16 Seeding duration

15. 15 /16 Seeding duration Previous results Pouwelse, IPTPS 2005 83% < 1 h Guo, IMC 2005 8% > 1 day

16. 16 /16 Source of incoming bytes

17. 17 /16 Conclusions Private vs. public Speed is 3-5 times faster Percentage of unconnectable peers is 1/2 Seeder/leecher ratio is at least 10 times higher Seeding duration is much longer The tit-for-tat mechanism is much less important