A nice way to test OpenFlow applications

Marco Canini, Daniele Venzano, Peter Perešíni, Dejan Kostić, Jennifer Rexford

Research output: Contribution to conferencePaperpeer-review

386 Scopus citations


The emergence of OpenFlow-capable switches enables exciting new network functionality, at the risk of programming errors that make communication less reliable. The centralized programming model, where a single controller program manages the network, seems to reduce the likelihood of bugs. However, the system is inherently distributed and asynchronous, with events happening at different switches and end hosts, and inevitable delays affecting communication with the controller. In this paper, we present efficient, systematic techniques for testing unmodified controller programs. Our NICE tool applies model checking to explore the state space of the entire system-the controller, the switches, and the hosts. Scalability is the main challenge, given the diversity of data packets, the large system state, and the many possible event orderings. To address this, we propose a novel way to augment model checking with symbolic execution of event handlers (to identify representative packets that exercise code paths on the controller). We also present a simplified OpenFlow switch model (to reduce the state space), and effective strategies for generating event interleavings likely to uncover bugs. Our prototype tests Python applications on the popular NOX platform. In testing three real applications-a MAC-learning switch, in-network server load balancing, and energy-efficient traffic engineering-we uncover eleven bugs.

Original languageEnglish (US)
Number of pages14
StatePublished - 2012
Event9th USENIX Symposium on Networked Systems Design and Implementation, NSDI 2012 - San Jose, United States
Duration: Apr 25 2012Apr 27 2012


Conference9th USENIX Symposium on Networked Systems Design and Implementation, NSDI 2012
Country/TerritoryUnited States
CitySan Jose

Bibliographical note

Publisher Copyright:
© 2012 by The USENIX Association. All Rights Reserved.

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Control and Systems Engineering


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