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

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

Network Love.mp3

ISP 1

Network Love.mp3

file transfer

ISP 2

Network Love.mp3

Peer C

Peer BPeer A

Reason: P2P networks employ arbitrary peer selection procedure

ISP 1

ISP 2

Network Love.mp3

Network Love.mp3

OracleService Peer C

Peer BPeer A

Solution: Oracle Service

ISP 1

ISP2

Network Love.mp3

Network Love.mp3

OracleService

query

Peer C

Peer BPeer A

Solution: Oracle Service

ISP 1

ISP 2

Network Love.mp3

Network Love.mp3

OracleService

query

1. Peer B2. Peer C

Peer C

Peer BPeer A

Solution: Oracle Service

ISP 1

ISP 2

Network Love.mp3

Network Love.mp3

OracleService

query

1. Peer B2. Peer C

file transferNetwork Love.mp3

Peer C

Peer BPeer A

Solution: Oracle Service

Benefits:

1.P2P users: improved query and file transfer performance

2. ISPs: decreased cost of inter-ISP traffic and

improved fairness

Implementation:

Set of replicated servers within each ISP

or

Web Service

Evaluation Metrics

Metric Explanation Ideal

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

max, Peersqp

max, Peersqp

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)

Impact of oracle on network graph properties

Metric Ideal Impact of oracle

mean degree of the peer

• large – within ISP• limited – outside ISP

Within ISP: increased from 4% to 59%

mean path length small Increased by 5%

Flow conductance large Decreased by ~50%

Impact of oracle on real P2P file sharing system

Gnutella protocol was modified to use oracle service

Metric Ideal Impact of oracle

mean degree of the peer

• large – within ISP• limited – outside ISP

Within ISP: increase from 14% to 82%

hop count diameter small Increases from 5-7 hops to 6-8 hops

mean path length small Up to 36% increase

Gnutella overlay topology