Shifting network tomography toward a practical goal

Date
2011
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Source Title
Proceedings of the 7th International Conference on Emerging Networking Experiments and Technologies, CoNEXT 2011
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Publisher
ACM
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Language
English
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Conference Paper
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Abstract

Boolean Inference makes it possible to observe the congestion status of end-to-end paths and infer, from that, the congestion status of individual network links. In principle, this can be a powerful monitoring tool, in scenarios where we want to monitor a network without having direct access to its links. We consider one such real scenario: a Tier-1 ISP operator wants to monitor the congestion status of its peers. We show that, in this scenario, Boolean Inference cannot be solved with enough accuracy to be useful; we do not attribute this to the limitations of particular algorithms, but to the fundamental difficulty of the Inference problem. Instead, we argue that the "right" problem to solve, in this context, is compute the probability that each set of links is congested (as opposed to try to infer which particular links were congested when). Even though solving this problem yields less information than provided by Boolean Inference, we show that this information is more useful in practice, because it can be obtained accurately under weaker assumptions than typically required by Inference algorithms and more challenging network conditions (link correlations, non-stationary network dynamics, sparse topologies).

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Keywords
Congestion status, Individual network, Inference algorithm, Inference problem, Monitoring tools, Network condition, Network dynamics, Network tomography, Nonstationary, Algorithms, Inference engines
Citation
Published Version (Please cite this version)