Systematically testing OpenFlow controller applications

Peter Perešíni, MacIej Kuźniar, Marco Canini, Daniele Venzano, Dejan Kostić, Jennifer L. Rexford

Research output: Contribution to journalArticle

Abstract

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 13 bugs.

Original languageEnglish (US)
Pages (from-to)270-286
Number of pages17
JournalComputer Networks
Volume92
DOIs
StatePublished - Dec 9 2015

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications

Keywords

  • Model checking
  • OpenFlow
  • Reliability
  • Software-defined networking
  • Symbolic execution

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    Perešíni, P., Kuźniar, M., Canini, M., Venzano, D., Kostić, D., & Rexford, J. L. (2015). Systematically testing OpenFlow controller applications. Computer Networks, 92, 270-286. https://doi.org/10.1016/j.comnet.2015.03.019