1. 1 EGOIST Overlay Routing using Selfish Neighbor Selection Georgios Smaragdakis Joint work with Vassilis Lekakis, Nikos Laoutaris, Azer Bestavros, John Byers and Mema Roussopoulos

2. 2 Overlay Networks Applications  Overlay routing  P2P file sharing  Content distribution networks  Multimedia streaming  Online multiplayer games  …. Overlay Plane Physical Plane O1O1 O2O2 O3O3 R4R4 R2R2 R7R7 R5R5 R6R6 R3R3 R1R1

3. 3 Connectivity Management  Full mesh architectures for reliability (e.g. RON)  Myopic heuristics random or proximity based neighbor selection  Tree forest or mesh construction to optimize multicast (e.g. Bullet, Splitstream)  Optimization for network delay (e.g. Detour, QRON)  Opportunistic choke/unchoke (e.g. BitTorrent)  Distributed hashing tables (e.g. Chord, Pastry, Tapestry)

4. 4 Selfish Neighbor Selection [Laoutaris, Smaragdakis, Bestavros, Byers, INFOCOM’07] Optimal wiring for v i : choose k neighbors, s.t. vivi u w min

5. 5 Selfish Neighbor Selection The selfish node can reap substantial performance. The performance gain is higher under uninformed overlays. The evolving stable graphs that consist of selfish nodes are highly optimized. Advantages The computation of the exact optimal wiring might be expensive. Requires full information about the network. The number of iterative wirings before stabilization might be high. Disadvantages

6. 6 EGOIST: Key Contributions System Architecture Link state protocol to support connectivity information dissemination. Overlay monitoring and maintenance mechanism. Computationally efficient neighbor selection. Performance Evaluation Average performance in real operational scenaria. Performance under different performance metrics (delay, system load, available bandwidth) Overhead of the implementation. Performance under churn. Vulnerability to malicious users. Applications.

7. 7 EGOIST: Basic Architecture 111.1.1.1 122.2.2.2 133.3.3.3 144.4.4.4 111.1.1.1 122.2.2.2 25msecs 111.1.1.1 133.3.3.3 165msecs 111.1.1.1 122.2.2.2 25msecs 111.1.1.1 133.3.3.3 165msecs 111.1.1.1 122.2.2.2 25msecs 111.1.1.1 133.3.3.3 165msecs 111.1.1.1 122.2.2.2 25msecs 111.1.1.1 133.3.3.3 165msecs 111.1.1.1 122.2.2.2 25msecs 111.1.1.1 133.3.3.3 165msecs 111.1.1.1 122.2.2.2 25msecs 111.1.1.1 133.3.3.3 165msecs 111.1.1.1 122.2.2.2 25msecs 111.1.1.1 133.3.3.3 165msecs 111.1.1.1 122.2.2.2 25msecs 111.1.1.1 133.3.3.3 165msecs X

8. 8 EGOIST: Basic Architecture 111.1.1.1 122.2.2.2 133.3.3.3 144.4.4.4

9. 9 EGOIST: Monitoring 111.1.1.1 122.2.2.2 133.3.3.3 144.4.4.4

10. 10 EGOIST: Monitoring 111.1.1.1 122.2.2.2 133.3.3.3 144.4.4.4

11. 11 EGOIST: Rewiring 111.1.1.1 122.2.2.2 133.3.3.3 144.4.4.4

12. 12 EGOIST: Newcomers 111.1.1.1 122.2.2.2 133.3.3.3 144.4.4.4 99.9.9.9

13. 12 EGOIST: Node Drop/Failure 111.1.1.1 122.2.2.2 133.3.3.3 144.4.4.4 133.3.3.3 DOWN

14. Objectives 13 Performance Evaluation: Experimental Setting Nodes:  50 PlanetLab nodes for 2 months. Wiring policies:  EGOIST  k-Random, k-Closest, k-Regular (DHT).  Wiring frequency: 60 seconds. Metrics of interest:  Delay (ping, Pyxida).  CPU load (loadavg).  Available Bandwidth (pathChirp). Control variables:  We vary the number (k) of neighbors. 30 11 7 1 1

15. 14 Performance Evaluation: Active Measurements EGOIST delay/EGOIST delay

16. 15 Performance Evaluation: Passive Measurements Wiring delay/EGOIST delay EGOIST

17. 16 Performance Evaluation: System Load 111.1.1.1 10% utilization

18. 17 Performance Evaluation: System Load EGOIST delay/EGOIST delay

19. 18 Performance Evaluation: Available Bandwidth 111.1.1.1 3Mbps1Mbps 3Mbps 2Mbps pathChirp

20. 19 Performance Evaluation: Available Bandwidth EGOIST bwth/EGOIST bwth

21. 20 Performance Evaluation: Re-wiring Frequency EGOIST wiring Approximate EGOIST wiring (e= 10%) CPU, memory and bandwidth consumption is minimal. EGOIST delay/optimal delay EGOIST re-wirings Appr. EGOIST/optimal delay Appr. EGOIST re-wirings Normalized delay

22. 21 Performance Under Churn: Hybrid-EGOIST 111.1.1.1 122.2.2.2 133.3.3.3 144.4.4.4

23. 22 Performance Under Churn Efficiency Index Connectivity quality EGOIST K-Random K-Regular K-Closest Hybrid-EGOIST

24. 23 Performance Under Churn Efficiency Index Connectivity quality EGOIST K-Random K-Regular K-Closest Hybrid-EGOIST

25. 24 Performance Under Cheating Delay/ Delay with abuse truthful EGOIST truthful EGOIST Untruthful Truthful Untruthful Truthful Many Untruthful nodesSingle Untruthful node

26. 25 Applications  Multi-path file transfer  Real-time VoIP  Online multiplayer P2P games [Quake III traces from Donnybrook, SIGCOMM’08] EGOIST k-Closest k-Random k-Regular

27. 26 Current Status  Explore worst case scenaria for cheating.  Study scalability.  Provide a general wiring service.

28. 28 http://csr.bu.edu/sns

29. 28 Thank you.