EigenTrust: Difference between revisions
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#REDIRECT [[Tit-For-Tat & EigenTrust Incentives#EigenTrust]] |
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EigenTrust is an incentive system based on traffic history of each peer. Uploading data to peer A increases the reputation of peer B from peer A's perspective. The reputation between all peers can be pictured using a trustmatrix <math>M</math> with elements <math>c_{i,j}</math>. <math>c_{i,j}</math> is peer ''j'' 's rank from ''i'' 's perspective related to normalized download volumes that ''i'' has received from ''j'' during a certain time period. In order to increase its local view of reputation, each peer takes into account his friends view (<math>M^2</math>). Thus the coverage of the rank matrix gets larger and it becomes less sparse. Continuing this step to its extreme (<math>M^{\infty}</math>), each column of <math>M</math> consists of the same values (= EigenTrust-vector), meaning that each peer has the same global view to other peers. |
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{| style="float:center; background:transparent; padding:0px; margin:0px;" |
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|[[Image:trustmatrix.jpg|thumb|center|300px|Downloadtraffic s mapped to a Trustmatrix M]] |
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A peer with large global reputation (EigenRank) gets higher download bandwidth and less latency. Moreover, peers with large EigenRank are preferred to download from. |
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= Simulation Results = |
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Examined in [[The_Maze_Peer-To-Peer_System|Maze-P2P-Network]], EigenTrust helped to punish colluding peers by branding them with low EigenRank. However, EigenTrust leaves some room for misinterpretations. |
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High reputation peers (super peers), which randomly download from "spam"-accounts, boost the EigenRank of these colluding peers. |
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On the other hand, peers inside satellite clusters like university networks are unfairly punished. A university network as a whole consumes by downloading much more than it uploads. Neglecting and underestimating internal cluster traffic, EigenTrust underrates cluster peers EigenRank. |
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Latest revision as of 16:26, 5 August 2007
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