1. An Overview of Peer-to-Peer Sami Rollins http://www.cs.ucsb.edu/~srollins

2. Outline What is P2P? Scope of P2P Applications File Sharing Applications System Design Challenges Approaches to P2P System Design Concluding Discussion

3. What is Peer-to-Peer (P2P)?

4. What is a peer? …an entity with capabilities similar to other entities in the system.

5. The Web Model Contact a server and download a web page. Server has all the resources and capabilities.

6. The P2P Model A peers resources are similar to the resources of the other participants P2P – peers communicating directly with other peers and sharing resources

7. P2P Application Taxonomy P2P Systems Distributed Computing SETI@home File Sharing Gnutella Collaboration Jabber Platforms JXTA

8. Distributed Computing

9. Collaboration sendMessagereceiveMessagesendMessagereceiveMessage

10. Collaboration sendMessagereceiveMessagesendMessagereceiveMessage

11. Platforms Find Peers…Send Messages GnutellaInstant Messaging

12. P2P File Sharing Content exchange –Gnutella File systems –Oceanstore Filtering/mining –Opencola

13. Challenges Peer discovery and group management Data location and placement Reliable and efficient file delivery Security/privacy/anonymity/trust

14. Design Concerns Per-node state Bandwidth usage Search time Fault tolerance/resiliency

15. Approaches Centralized Flooding Document Routing

16. Centralized BobAlice JaneJud y

17. Centralized Benefits: –Efficient search –Limited bandwidth usage –No per-node state Drawbacks: –Central point of failure –Limited scale

18. Flooding Bob Alice Jane Judy Carl

19. Flooding Benefits: –No central point of failure –Limited per-node state Drawbacks: –Slow searches –Bandwidth intensive

20. Document Routing 001 012 212 305 332 212 ?

21. Document Routing Benefits: –More efficient searching –Limited per-node state Drawbacks: –Limited fault-tolerance vs redundancy

22. Points of Discussion Do P2P applications/systems have common research questions? What are the killer apps for P2P systems? What are the benefits of choosing P2P?

23. An Overview of Peer-to-Peer Sami Rollins http://www.cs.ucsb.edu/~srollins Mills College – 2/25/03

24. Modified version of slide from another presentation CAN: simple example 1 234 5 670 1 2 3 4 5 6 7 0 n1

25. Modified version of slide from another presentation CAN: simple example 12

26. Modified version of slide from another presentation CAN: simple example 1 2 3

27. Modified version of slide from another presentation CAN: simple example 1 2 3 4

28. Modified version of slide from another presentation CAN: simple example

29. Modified version of slide from another presentation CAN: routing table

30. Modified version of slide from another presentation CAN: routing (a,b) (x,y)

31. Modified version of slide from another presentation CAN: node insertion Bootstrap node 1) Discover some node I already in CAN new node

32. Modified version of slide from another presentation CAN: node insertion I new node 1) discover some node I already in CAN

33. Modified version of slide from another presentation CAN: node insertion 2) pick random point in space I (p,q) new node

34. Modified version of slide from another presentation CAN: node insertion (p,q) 3) I routes to (p,q), discovers node J I J new node

35. Modified version of slide from another presentation CAN: node insertion new J 4) split Js zone in half… new owns one half

36. Remaining Problems?

37. Hard to handle highly dynamic environments Methods dont consider peer characteristics Usable services

38. P2P Goals/Benefits Cost sharing Resource aggregation Improved scalability/reliability Increased autonomy Anonymity/privacy Dynamism Ad-hoc communication