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CSTalks - Peer-to-peer - 16 Feb
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CSTalks - Peer-to-peer - 16 Feb

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  • 1. Peer-to-peer: past, present, futureCristina Cărbunaru16 February 2011
  • 2. Peer-to-peer Internet today ◦ Large number of hosts ◦ Large amount of content Significant challenges for traditional client-server architectures Make use of the inter-connectivity of the nodes in the Internet ◦ Alleviate the load from servers 2
  • 3. Client-server vs. P2p 3
  • 4. The Peer Double function: ◦ Client - consumer ◦ Server - producer Incentives to offer service, not just benefit from service More peers means more capacity added to the system 4
  • 5. P2p Goals Reduced central control Heterogeneity Flat topology Autonomy Fault resilience… 5
  • 6. History File sharing applications ◦ 1999: Napster ◦ Gnutella, Kazaa, Freenet ◦ 2001: BitTorrent (Bram Cohen) ◦ Multiple variations of p2p programs Nowadays: ◦ File sharing – among individual users or in the data centers ◦ Media streaming – on-demand or live content ◦ Communication – Skype! 6
  • 7. The beginnings: Napster 7
  • 8. BitTorrent Seed Tracker 8
  • 9. BitTorrent SeedLeecher Tracker 9
  • 10. BitTorrent 10
  • 11. BitTorrent 11
  • 12. BitTorrent 12
  • 13. BitTorrent 13
  • 14. BitTorrent 14
  • 15. BitTorrent 15
  • 16. BitTorrent Free-rider 16
  • 17. Swarm Behavior Incentive mechanisms ◦ Why offer service? Flash crowd ◦ Large number of peers choke the performance Steady state ◦ Number of peers stays constant over time ◦ Easy to predict performance Lifetime ◦ When and why is the torrent dying? ... 17
  • 18. Peer Behavior Free riding ◦ Evaluate performance loss ◦ Methods to prevent Best results with minimum of effort ◦ Cheating, but not exactly Clustering of peers ◦ Peers download/upload to similar bandwidth peers Security of content ◦ Malicious data Connectivity ◦ NAT boxes 18
  • 19. Approaches Measurement ◦ Real swarms ◦ Experimental platforms: PlanetLab, EmuLab Simulation Modeling Proposing new p2p protocols that solve different problems ◦ Proportional upload bandwidth: PropShare ◦ Amount of data transferred: Avalanche ◦ Upload bandwidth allocation among peers to get the best download speed: BitTyrant 19
  • 20. P2p in 2008/2009 (Ipoque study) 20
  • 21. Popularity Decreasing popularity for p2p file sharing ◦ Packet filtering ◦ Packet inspection ◦ Lawsuit against Pirate Bay ◦ … One click file hosting services (Rapidshare, Hotfile) become popular 21
  • 22. What to Research? Packet filtering ◦ Glasnost Hiding identity ◦ Tor ◦ Anonymous p2p Copyright issues ◦ Download might be legal in some countries ◦ Upload is illegal … 22
  • 23. What’s Next? Increasing usage of p2p protocols in other contexts: ◦ Media streaming, communication ◦ Inside the data centers ◦ Social networks ◦ Economics 23
  • 24. Future New technologies ◦ IPv6 ◦ Mobile devices From computer-to-computer to human-to-human ◦ commons-based peer production (Yochai Benkler):  Peer governance  Peer property  Peer distribution 24
  • 25. Conclusions Successful piece of research ◦ P2p transcended computer science Changed the way we share ◦ Files ◦ Knowledge ◦ Peer generated content P2p is here to stay! 25
  • 26. Questions? Thank you! 26