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MINP Model-based Inference of Network Properties Overview
Informally, a dominant congested link is one that produces most of the losses and significant queuing delays on an end-to-end network path. Identifying whether a dominant congested link exists along a path is important for network management and engineering. It is also important for understanding the dynamics of the network. When using end-to-end measurements to identify whether a dominant congested link exists, the difficulty is that no information about a particular link (e.g., link capacity, utilization) is directly revealed by the end-to-end measurements. We propose a novel model-based approach to address this challenge. We periodically send probing packets from one host to another so as to obtain a sequence of delay and loss values. The key insight in our approach is to utilize the queuing delay properties of the lost probes. For example, if one link along the path is solely responsible for all losses, then all lost probes have the property that they ``see'' a full queue at this link. We interpret a loss as an unobserved delay and define the queuing delay of that lost packet as a virtual queuing delay. We then propose a Markov model with a hidden dimension, to infer the virtual queuing delay distribution from the measured delay and loss observations. Based on the inferred virtual queuing delay distribution, we design hypothesis tests to identify whether a dominant congested link exists along a network path. Our approach utilizes the delay and loss observations jointly for inference instead of the common approach of treating them separately. Furthermore, our model-based approach fully utilizes information obtained from the probing packets and enables very fast identification. Validation using ns simulation and Internet experiments demonstrates that this approach can correctly identify the existence of a dominant congested link within minutes. : |
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Virtual queuing delay distribution of a strongly dominant congested link. Qk is the minimum queue delay of the link. D is the minimum queuing delay along the path. |
Estimate of the maximum queuing delay of a weakly domint congested link
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Papers
· Model-based Identification of Dominant Congested Links
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