Ahmed El-Hassany is a second-year Ph.D. student at ETH Zürich, who researches ways to make networks more programmable and to verify the correctness of programmable networks. I caught up with Ahmed at SOSR, the Symposium on SDN Research, where he presented BigBug: Practical

Concurrency Analysis for SDN, a paper that he authored along with Roman May, Laurent Vanbever, and Martin Vechev. The paper's abstract is:

By operating in highly asynchronous environments, SDN controllers often

suffer from bugs caused by concurrency violations. Unfortunately,

state-of-the-art concurrency analyzers for SDNs often report thousands

of true violations, limiting their effectiveness in practice.

This paper presents BigBug, an approach for automatically identifying

the most representative concurrency violations: those that capture the

cause of the violation. The two key insights behind BigBug are that:

(i) many violations share the same root cause, and (ii) violations with

the same cause share common characteristics. BigBug leverages these

observations to cluster reported violations according to the similarity

of events in them as well as SDN-specific features. BigBug then

reports the most representative violation for each cluster using a

ranking function.

We implemented BigBug and showed its practical effectiveness. In more

than 100 experiments involving different controllers and applications,

BigBug systematically produced 6 clusters or less, corresponding to a

median decrease of 95% over state-of-the-art analyzers. The number of

violations reported by BigBug also closely matched that of actual bugs,

indicating that BigBug is effective at identifying root causes of SDN

races.

For more information on BigBug, visit the SDNRacer website. You can find contact information for Ahmed on his webpage.

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