Evaluation GUESS and Non-Forwarding

Peer-to-Peer search

ICDCS paper Beverly YangPatrick VinogradHector Garcia-MolinaComputer Science Department, Stanford University

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Outline Introduction GUESS Protocol GUESS vs. Gnutella Policies Maintaining the Link Cache Conclusion Gain and Question

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Introduction The key to the usability of P2P

To search for and retrieve efficient DHT-based search technique

Focused on the availability control the placement of data and

the topology of the networks

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Introduction part 2Forwarding-based

Forwarding until the stop criterion is met

Difficulty To control how many peer receive

the message Which peers receive message

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Introduction part 3Non-forwarding search

Peers directly probe each other

Under GUESS protocol

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Introduction part 4The focus point of paper

When processing the query In what order should peers be

probed

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GUESS Protocol part 1Basic architecture

Two cache, or lists of pointer (IP address) Link cache Query cache { IP address of Q, TS, NumFiles,

NumRes }

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GUESS Protocol part 2Maintaining state

Make sure entries in the cache are fresh

Ping message Pong message Introduction protocol

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GUESS Protocol part 3Query propagation

Iteratively probe, unicast query

After sending , peer either receive the reply or wait for a timeout period

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GUESS vs. Gnutella part 1 Query performance

Gnutella The number reached is determined

by the flooding GUESS

Peer has control the order and decides how many peers to probe

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GUESS vs. Gnutella part 2 State maintenance

Gnutella Consistent of active network connection.

GUESS Each peer maintains the pointer caches Cache size limited by memory. No explicit notification when new peer

joins in, it need the probing to know the new peer.

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GUESS vs. Gnutella part 3 Security

Selfish Gnutella

Fairly robust GUESS

Could easily probe more peers Imposing a higher load than the

necessary

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GUESS vs. Gnutella part 4Security

Malicious peers Gnutella

Vulnerable to denial of service (DoS)

GUESS Cause the heavy network traffic

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GUESS vs. Gnutella part 5Fragmentation attack

Gnutella Highly-connected peers are

attacked GUESS

Malicious peers propagate their identities to the network, and suddenly disappear.

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Policies part 1 Determining how the entries or

der are used and maintained. Five type of policies

QueryProbe QueryPong PingProbe PingPong CacheReplacement

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Policies part 2The implemented policies

Random (Ran)Most Recently Used (MRU)Leased Recently Used (LRU)Most Files Shared (NFS)Most Results (MR)

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Result part 1 Maintaining the Link Cache

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Result part 2 Maintaining the Link Cache

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Result part 3 Maintaining the Link Cache

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Result part 4Flexible Extent

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Result part 5Query Efficiency

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Result part 6Query Efficiency

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Result part 7Query Efficiency

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Result part 8Unsatisfied Queries

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Result part 9 fairness

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Result part 10Capacity Limits

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Result part 11Capacity Limits

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Conclusion To achieve very efficient query

performance MR policy policy presents the

best tradeoff between efficiency and robustness.

First-generation implementation of GUESS would be to use the MR policy.

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Future workHow to make the protocol

adapt to changing network condition.

How to define against selfish and malicious peers

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Gain and QuestionNetwork sizeConcept of cache

ContentSize