1. 20-11-20071 1 Tribler Download Core Improvement IN3700 Bachelor Thesis Presentation by Rick van Hattem Raynor Vliegendhart Committee Dr. Ir. J.A. Pouwelse Ir. B.R. Sodoyer

2. 20-11-2007 2 2 Overview Introduction Problem Analysis Evolution of BitSMART (our measurement tool) Shortcomings of BitSMART Acquired Insights Project’s Delays Demonstration Conclusion and Future Work Questions

3. 20-11-2007 3 3 Introduction (1) Users want to share files Peer-to-peer file sharing protocols BitTorrent is popular Azureus µTorrent Mainline ABC BitTornado BitTyrant BitComet Tribler et cetera…

4. 20-11-2007 4 4 Introduction (2) Sharing versus Leeching BitTorrent incents users to share Reward: performance How does Tribler fare? Measuring is knowing!

5. 20-11-2007 5 5 Problem Analysis Performance  Behaviour So what is good sharing behaviour? Depends on point of view of other peers Upload bandwidth is scarce Ergo: bandwidth = currency Research the best strategy: Optimize the value of your upload bandwidth

6. 20-11-2007 6 6 Evolution of BitSMART (1) Original project’s goal: Analysis and Implementation Approach: Logging (next slide)

7. 20-11-2007 7 7 Evolution of BitSMART (2) logging

8. 20-11-2007 8 8 Evolution of BitSMART (3) Disadvantages: Not scalable Limited applicability Advantage: All BitTorrent information readily available in memory

9. 20-11-2007 9 9 Evolution of BitSMART (4) Project’s change: Focus on Analysis only Approach: Network traffic analysis (next slide)

10. 20-11-2007 10 20-11-200710 Evolution of BitSMART (5) usual BT stackcapture part

11. 20-11-2007 11 20-11-200711 Evolution of BitSMART (6) Advantages: Scalable Can be applied to all clients Disadvantages: Considerable more effort to implement Not 100% reliable, encrypted connections cannot be deciphered

12. 20-11-2007 12 20-11-200712 Shortcomings of BitSMART (1) Two possible alternative implementations: PCAP (raw Ethernet frames) PDML (XML format) Choice: PDML format Why? It seemed to be: Easier Less error prone Less time to implement

13. 20-11-2007 13 20-11-200713 Shortcomings of BitSMART (2) Unfortunately, the easy path was deceiving Large PDML files: DOM readers not feasible PDML missing details Packets lost in translation, PCAP  PDML

14. 20-11-2007 14 20-11-200714 Shortcomings of BitSMART (3) Consequences: Dealing with these drawbacks cost a lot of time Missing details made the resulting tool less powerful

15. 20-11-2007 15 20-11-200715 Shortcomings of BitSMART (4) Choosing PCAP would have prevented a lot of problems However, it would still have cost a lot of time to implement Reason: Lots of low level tasks to be done

16. 20-11-2007 16 20-11-200716 Acquired Insights (1) Due to the limitations of the PDML format, analysis was not as in-depth as desired Nevertheless, we acquired some interesting insights

17. 20-11-2007 17 20-11-200717 Acquired Insights (2) Attaining high download speeds as fast as possible Finding and trying out peers is important

18. 20-11-2007 18 20-11-200718 Acquired Insights (3) Endgame mode’s purpose is to retain speed

19. 20-11-2007 19 20-11-200719 Acquired Insights (4) Explanation for Mainline’s bad performance: Peer discovery not aggressive

20. 20-11-2007 20 20-11-200720 Acquired Insights (5) However, a later measurement surprised us: Mainline was the fastest Mainline found the least amount of peers MainlineTribler

21. 20-11-2007 21 20-11-200721 Acquired Insights (6) A possible explanation: Mainline was lucky and immediately found good peers Finding/Trying out peers costs time If true, adaptive strategies are rewarding

22. 20-11-2007 22 20-11-200722 Project’s Delays (1) Original planning: Begin of May to begin of July Progress went fine Project’s change: Begin of June Re-planning failed: New tasks heavily underestimated

23. 20-11-2007 23 20-11-200723 Project’s Delays (2) Underestimation caused by Being optimistic Trying to fit the new tasks in the remaining time Underestimation was a source of delay Due to the delay, other conflicting events increased the delay

24. 20-11-2007 24 20-11-200724 Demonstration (1) A true live demonstration not possible, so we show a few preliminary steps on these slides.

25. 20-11-2007 25 20-11-200725 Demonstration (2) First, we start tshark

26. 20-11-2007 26 20-11-200726 Demonstration (3) Then, start the BitTorrent client to be measured Start the download

27. 20-11-2007 27 20-11-200727 Demonstration (4) After the download, stop the BT client and tshark Process the captured packets with BitSMART Enjoy the live demonstration!

28. 20-11-2007 28 20-11-200728 Conclusion and Future Work (1) Tribler is one of the slowest BitTorrent clients Main improvements in: Peer discovery Endgame mode To be researched: Adaptive strategies

29. 20-11-2007 29 20-11-200729 Conclusion and Future Work (2) BitSMART: Tool is usable, but limited in power PDML format is a dead-end Effort should be spent in writing a PCAP analyser Reason for further research: Measuring is knowing!

30. 20-11-2007 30 20-11-200730 Questions?