en>Headbomb: Various citation cleanup (identifiers mostly) using AWB

2011-09-05T07:01:19Z

Various citation cleanup (identifiers mostly) using AWB

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[[File:phoenix arch.png|thumb|350px|Weighted-based NC calculation in Phoenix]]
'''Phoenix''' is a decentralized [[network coordinate]] (NC) system based on the [[matrix factorization]] model.<ref name="Phoenix_Chen11">{{Cite journal
| author = Y. Chen, X. Wang, C. Shi, and et al.
| url = http://www.cs.duke.edu/~ychen/papers/Phoenix_TNSM.pdf
| format=PDF
| title = Phoenix: A Weight-based Network Coordinate System Using Matrix Factorization
| month = December
| volume = 8
| issue = 4
| pages = 334–347
| journal = [[IEEE Transactions on Network and Service Management]]
| year = 2011
}}</ref>

== Background ==
* Network coordinates (NC) system<ref>{{Cite journal
| author = B. Donnet, B. Gueye, M.A. Kaafar
| title = A Survey on Network Coordinates Systems, Design, and Security
| journal = IEEE Communications Surveys & Tutorials
| volume = 12
| issue = 4
| pages = 488–503
| year = 2010
| url = http://planete.inrialpes.fr/people/kaafar/survey-normal.pdf
| doi = 10.1109/SURV.2010.032810.00007
}}</ref> is an efficient mechanism for Internet distance ([[round-trip latency]]) prediction with scalable measurements. For a network with N hosts, by performing O(N) measurements, all N*N distances can be predicted.
* Use cases: [[Vuze]] BitTorrent, application layer multicast, PeerWise overlay, multi-player online gaming.
* [[Triangle inequality]] violation (TIV) is widely exist on the Internet due to the current sub-optimal [[Internet routing]].

== Model ==
* Most of the prior NC systems utilize the Euclidean distance model, i.e., embeds N hosts into a d-dimensional [[Euclidean space]] '''R'''<sup>''d''</sup>. Due to the wide existence of TIV on the Internet, the prediction accuracy of such systems is limited. Phoenix chooses [[Matrix factorization]] (MF) model, which does not have the constraint of TIV.
* The [[linear dependence]] among the rows motivates the factorization of Internet distance matrix, i.e., for a system with <math>N</math> Internet nodes, the <math>N \times N</math> Internet distance matrix D can be factorized into two smaller matrices. <math>D \approx XY^T</math> where <math>X</math> and <math>Y</math> are <math>N \times d</math> matrices (d << N). This matrix factorization is essentially a problem of linear dimensionality reduction, while Phoenix try to solve it via a distributed way.

== Design choices in Phoenix ==
* Different from the existing MF based NC systems such as IDES<ref name="IDES_Mao06">{{Cite journal
| author = Yun Mao, Lawrence Saul and Jonathan M. Smith
| title = IDES: An Internet Distance Estimation Service for Large Networks
| journal = [[IEEE Journal on Selected Areas in Communications]]
| url = http://www2.research.att.com/~maoy/pub/ides_jsac06.pdf
| format=PDF
| month = December
| volume = 24
| issue = 12
| pages = 2273–2284
| year = 2006
| doi=10.1109/JSAC.2006.884026
}}</ref> and DMF,<ref>{{Cite conference
| author = Y. Liao, P. Geurts and G. Leduc
| year = 2010
| url = http://www.run.montefiore.ulg.ac.be/~liao/papers/networking2010_liao.pdf
| format=PDF
| title = Network Distance Prediction Based on Decentralized Matrix Factorization
| booktitle = Proc. of IFIP Networking
}}</ref> Phoenix introduces a '''weight''' to each reference NC and trusts the NCs with higher weight values more than the others. The weight based mechanism can substantially reduce the impact of the error propagation.
* For node discovery, Phoenix utilizes a distributed scheme, so-called [[Peer exchange]] (PEX), which is used in [[BitTorrent (protocol)]]. The usage of PEX reduces the load of the tracker, while still ensuring the prediction accuracy under node churn.
* Similar to DMF, for avoiding the potential drift of the NCs, [[Regularization (mathematics)]] is introduced in NC calculation.
* NCShield<ref>{{Cite conference
| author = Shining Wu,Yang Chen, Xiaoming Fu, Jun Li
| year = 2012
| url = http://www.cs.duke.edu/~ychen/papers/NCShield_IWQoS12.pdf
| title = NCShield: Securing Decentralized, Matrix Factorization-Based Network Coordinate Systems
| booktitle = Proc. of the 20th IEEE/ACM International Workshop on Quality of Service (IWQoS'12)
}}</ref> is a decentralized, goosip-based trust and reputation system to secure Phoenix and other matrix factorization-based NC systems.

== See also ==
* [[Vivaldi coordinates]]
* [[Pharos Network Coordinates]]
* [[Global network positioning]]
* [http://www.cs.duke.edu/~ychen/Project_Phoenix.html An open source simulator of Phoenix]

== References ==
{{Reflist}}

[[Category:Computer networking]]

{{compu-network-stub}}

Continuous dual Hahn polynomials - Revision history

en>Headbomb: Various citation cleanup (identifiers mostly) using AWB