1 a connection management protocol for promoting cooperation in peer-to-peer networks authors: murat...
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A connection management protocol for promoting cooperation in Peer-to-Peer networks
Authors: Murat Karakaya, Ibrahim Korpeoglu, and Ozgur UlusoySource: Computer Communications, vol. 31, pp. 240–256, 2008Speaker: Shu-Fen Chiou ( 邱淑芬 )
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Outline Introduction Gnutella Free rider Proposed scheme P2P Connection Management Protocol
(PCMP) Simulation result Attacks Conclusion Comments
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Introduction Gnutella (Host Cache)
It is a pure P2P protocol in contrast with Napster It is a broadcast-type network The core of the protocol consists of 5 descriptors
PING, PONG, QUERY, QUERY HIT and PUSH A Peer needs to connect to 1 or more other Gnutella Peers
in order to participate in the networkGnutella Network N
Server p
QUERY1
QUERY HIT
2
Server p2
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Introduction
Find Hosts
Gnutella
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Introduction
Ping
Gnutella
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Introduction
Pong
Gnutella
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Introduction
Pong
Gnutella
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Introduction
Pong
Gnutella
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Introduction
Query
Gnutella
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Introduction
Query TTL=2
Gnutella
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Introduction
queryQuery TTL=3
Gnutella
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Introduction
Query Hit
Gnutella
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Introduction
Download File
Gnutella
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Free rider
Download File
Query
Free rider
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Proposed scheme Proposed two connection types. Proposed a P2P Connection Management
Protocol (PCMP). Benefits:
The connectivity of free riders to the contributing peers can be reduced.
In some situations, free riders can be totally isolated from the contributors.
The connectivity among contributor peers can be increased.
The workload of a contributor peer can be reduced, since it will not serve many free riders anymore.
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General P2P connection
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Two connection types
IN-connection and OUT-connection Limiting the numbers of
connection.
IN-connection
OUT-connection
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P2P Connection Management Protocol (PCMP) 2 IN-connections, 2 OUT-
connections
A BDownload file
C
DIN-connection
IN-connection
Requester(Downloader)
Responder(Uploader)A
According download times(C-PCMP) or update time (T-PCMP)
IN-connection
IN-connectionB
OUT-connectionPing
Pong
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P2P Connection Management Protocol (PCMP) 4 IN-connections, 4 OUT-
connections TTL=2Contributor
Contributor
F1, F3
F2Query F1
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P2P Connection Management Protocol (PCMP)
Contributor
Contributor
F1, F3
F2
Query F2
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Simulation results
900 peers
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Attacks
Malicious peer refuse to add a contributor to its list of IN-connections after downloading file. Contributors establish OUT-
connections only with other contributors. This attack will not affect.
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Attacks A malicious peer replies with a
faked Query Hit. In PCMP, the connection between two
peers is established after a file is download. If the file is wrong, the downloader will not send Pong message.
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Attacks
A malicious peer behaves as a new-comer to gain more OUT-connections. Try to reduce this attack according
others’ methods.
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Conclusion
Proposed a novel approach and a P2P Connection Management Protocol (PCMP).
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Comments
Prevent the third attack. Increase its OUT-connections by:
Increasing answering power. Increasing the number of edges. Increasing the amount of capacity
used to service neighbors’ queries. Increasing the length of period for
servicing neighbors’ queries.