1. Can ISPs and P2P Users Cooperate for Improved Performance? Vinay Aggarwal, Anja Feldmann (German Telecom Laboratories) Christian Scheideler (TU, Munchen) ACM SIGCOMM Computer Communication Review

2. Problem: file content available within the querying node’s ISP is downloaded from a node outside the ISP

3. Reason: P2P networks employ arbitrary peer selection procedure

4. Solution: Oracle Service

8. Benefits: 1.P2P users: improved query and file transfer performance 2.ISPs: decreased cost of inter-ISP traffic and improved fairness

9. Implementation: Set of replicated servers within each ISP or Web Service

10. Evaluation Metrics MetricExplanationIdeal degree of the peer # of connections to other peers large – within ISP limited – outside ISP hop count diameter (hop count b/n p and q) small ISP diameter (path_cost(ISP(p),ISP(q))) small Flow conductance ~ Good connectivity, low congestion large

11. Simulations Impact of the oracle: 1) on network graph properties 2) on a real P2P file sharing system Simulations are based on current ISP topology (derived from BGP routing information)

12. Impact of oracle on network graph properties MetricIdealImpact of oracle mean degree of the peer large – within ISP limited – outside ISP Within ISP: increased from 4% to 59% mean path lengthsmallIncreased by 5% Flow conductancelargeDecreased by ~50%

13. Impact of oracle on real P2P file sharing system Gnutella protocol was modified to use oracle service MetricIdealImpact of oracle mean degree of the peer large – within ISP limited – outside ISP Within ISP: increase from 14% to 82% hop count diametersmallIncreases from 5-7 hops to 6-8 hops mean path lengthsmallUp to 36% increase

14. Gnutella overlay topology