1. 1 Modeling peer-peer file sharing systems Ge, Z.; Figueiredo, D.R.; Sharad Jaiswal; Kurose, J.; Towsley, D.; INFOCOM 2003. Twenty-Second Annual Joint Conference of the IEEE Computer and Communications Societies. Presentation by Tony Sung, MC Lab, IE CUHK 23th September 2004

2. 2 Outline  Significance of the Paper  Modeling P2P Systems  Capturing the Parameters  The Results  Conclusion

3. 3 Significance of the Paper Mathematical Model that addresses Scalability Impact of freeloaders Impact of imbalanced service capacity and file request load

4. 4 Significance of the Paper Results Limited-scope flooding worsen performance Freeloaders do not have significant impact Centralized indexing approach can scale gracefully up to its capacity Degradation due to replication-popularity mismatch is minor

5. 5 Modeling P2P Systems Modeling

6. 6 Modeling P2P Systems 3 types of systems CIA – Centralized Indexing Architecture DIFA – Distributed Indexing with Flooding Architecture DIHA – Distributed Indexing with Hashing Architecture

7. 7 Modeling P2P Systems  A multiple class closed queuing network C classes of peers: N = (N (1),…, N (C) ) M number of distinct files sorted according to availability States  Thinking, Querying, Downloading, Offline

8. 8 Modeling P2P Systems

9. 9 Capturing the Parameters Capturing Parameters

10. 10 Capturing the Parameters

11. 11 A single class case, C = 1, N a = (N a (1) ) (Popularity, Zipf, assumed …) (File service rate) ? (Common services’ service rate) ? (Query Failure Rate) Capturing the Parameters

12. 12 Common services ’ service rate CIA: DIFA: DIHA: Capturing the Parameters

13. 13 Query failure rate CIA: DIFA: DIHA: Capturing the Parameters

14. 14 Freeloaders: 2 classes Capturing the Parameters

15. 15 Solving the model Visiting Ratio Service Demand Bottleneck Queue

16. 16 Results

17. 17 Results Scalability CIA DIFA DIHA CIA DIFA

18. 18 Results Freeloader ’ s impact on system throughput Non- freeloader population

19. 19 Results Freeloader ’ s impact on non-freeloader throughput Non- freeloader population

20. 20 Results Reason of DIFA ’ s poor performance

21. 21 Results Mismatch in file popularity and replication

22. 22 Results Mismatch in file popularity and replication

23. 23 Conclusion  Simple, representative math. Model  Flexible across architectures  Dealt with different classes of peers

24. 24 Results Freeloader ’ s impact on system throughput - another perspective