1. Evaluation GUESS and Non-Forwarding Peer-to-Peer search ICDCS paper Beverly Yang Patrick Vinograd Hector Garcia-Molina Computer Science Department, Stanford University

2. 2004.12.1 By 溫健順 2 Outline Introduction GUESS Protocol GUESS vs. Gnutella Policies Maintaining the Link Cache Conclusion Gain and Question

3. 2004.12.1 By 溫健順 3 Introduction The key to the usability of P2P  To search for and retrieve efficient DHT-based search technique  Focused on the availability  control the placement of data and the topology of the networks

4. 2004.12.1 By 溫健順 4 Introduction part 2 Forwarding-based  Forwarding until the stop criterion is met  Difficulty  To control how many peer receive the message  Which peers receive message

5. 2004.12.1 By 溫健順 5 Introduction part 3 Non-forwarding search  Peers directly probe each other  Under GUESS protocol

6. 2004.12.1 By 溫健順 6 Introduction part 4 The focus point of paper  When processing the query  In what order should peers be probed

7. 2004.12.1 By 溫健順 7 GUESS Protocol part 1 Basic architecture  Two cache, or lists of pointer (IP address) Link cache Query cache { IP address of Q, TS, NumFiles, NumRes }

8. 2004.12.1 By 溫健順 8 GUESS Protocol part 2 Maintaining state Make sure entries in the cache are fresh Ping message Pong message Introduction protocol

9. 2004.12.1 By 溫健順 9 GUESS Protocol part 3 Query propagation  Iteratively probe, unicast query  After sending, peer either receive the reply or wait for a timeout period

10. 2004.12.1 By 溫健順 10 GUESS vs. Gnutella part 1 Query performance  Gnutella The number reached is determined by the flooding  GUESS Peer has control the order and decides how many peers to probe

11. 2004.12.1 By 溫健順 11 GUESS vs. Gnutella part 2 State maintenance  Gnutella Consistent of active network connection.  GUESS Each peer maintains the pointer caches Cache size limited by memory. No explicit notification when new peer joins in, it need the probing to know the new peer.

12. 2004.12.1 By 溫健順 12 GUESS vs. Gnutella part 3 Security  Selfish Gnutella  Fairly robust GUESS  Could easily probe more peers  Imposing a higher load than the necessary

13. 2004.12.1 By 溫健順 13 GUESS vs. Gnutella part 4 Security  Malicious peers Gnutella  Vulnerable to denial of service (DoS) GUESS  Cause the heavy network traffic

14. 2004.12.1 By 溫健順 14 GUESS vs. Gnutella part 5 Fragmentation attack Gnutella  Highly-connected peers are attacked GUESS  Malicious peers propagate their identities to the network, and suddenly disappear.

15. 2004.12.1 By 溫健順 15 Policies part 1 Determining how the entries order are used and maintained. Five type of policies  QueryProbe  QueryPong  PingProbe  PingPong  CacheReplacement

16. 2004.12.1 By 溫健順 16 Policies part 2 The implemented policies  Random (Ran)  Most Recently Used (MRU)  Leased Recently Used (LRU)  Most Files Shared (NFS)  Most Results (MR)

17. 2004.12.1 By 溫健順 17 Result part 1 Maintaining the Link Cache

18. 2004.12.1 By 溫健順 18 Result part 2 Maintaining the Link Cache

19. 2004.12.1 By 溫健順 19 Result part 3 Maintaining the Link Cache

20. 2004.12.1 By 溫健順 20 Result part 4 Flexible Extent

21. 2004.12.1 By 溫健順 21 Result part 5 Query Efficiency

22. 2004.12.1 By 溫健順 22 Result part 6 Query Efficiency

23. 2004.12.1 By 溫健順 23 Result part 7 Query Efficiency

24. 2004.12.1 By 溫健順 24 Result part 8 Unsatisfied Queries

25. 2004.12.1 By 溫健順 25 Result part 9 fairness

26. 2004.12.1 By 溫健順 26 Result part 10 Capacity Limits

27. 2004.12.1 By 溫健順 27 Result part 11 Capacity Limits

28. 2004.12.1 By 溫健順 28 Conclusion To achieve very efficient query performance MR policy policy presents the best tradeoff between efficiency and robustness. First-generation implementation of GUESS would be to use the MR policy.

29. 2004.12.1 By 溫健順 29 Future work How to make the protocol adapt to changing network condition. How to define against selfish and malicious peers

30. 2004.12.1 By 溫健順 30 Gain and Question Network size Concept of cache  Content  Size