VeriCon: Towards verifying controller programs in software-defined networks

Thomas Ball, Nikolaj Bjørner, Aaron Gember, Shachar Itzhaky, Aleksandr Karbyshev, Mooly Sagiv, Michael Schapira, Asaf Valadarsky

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

150 Scopus citations


Software-defined networking (SDN) is a new paradigm for operating and managing computer networks. SDN enables logicallycentralized control over network devices through a "controller" software that operates independently from the network hardware, and can be viewed as the network operating system. Network operators can run both inhouse and third-party SDN programs (often called applications) on top of the controller, e.g., to specify routing and access control policies. SDN opens up the possibility of applying formal methods to prove the correctness of computer networks. Indeed, recently much effort has been invested in applying finite state model checking to check that SDN programs behave correctly. However, in general, scaling these methods to large networks is challenging and, moreover, they cannot guarantee the absence of errors. We present VeriCon, the first system for verifying that an SDN program is correct on all admissible topologies and for all possible (infinite) sequences of network events. VeriCon either confirms the correctness of the controller program on all admissible network topologies or outputs a concrete counterexample. VeriCon uses first-order logic to specify admissible network topologies and desired network-wide invariants, and then implements classical Floyd- Hoare-Dijkstra deductive verification using Z3. Our preliminary experience indicates that VeriCon is able to rapidly verify correctness, or identify bugs, for a large repertoire of simple core SDN programs. VeriCon is compositional, in the sense that it verifies the correctness of execution of any single network event w.r.t. the specified invariant, and can thus scale to handle large programs. To relieve the burden of specifying inductive invariants from the programmer, VeriCon includes a separate procedure for inferring invariants, which is shown to be effective on simple controller programs. We view VeriCon as a first step en route to practical mechanisms for verifying network-wide invariants of SDN programs.

Original languageAmerican English
Title of host publicationPLDI 2014 - Proceedings of the 2014 ACM SIGPLAN Conference on Programming Language Design and Implementation
PublisherAssociation for Computing Machinery
Number of pages12
ISBN (Print)9781450327848
StatePublished - 2014
Event35th ACM SIGPLAN Conference on Programming Language Design and Implementation, PLDI 2014 - Edinburgh, United Kingdom
Duration: 9 Jun 201411 Jun 2014

Publication series

NameProceedings of the ACM SIGPLAN Conference on Programming Language Design and Implementation (PLDI)


Conference35th ACM SIGPLAN Conference on Programming Language Design and Implementation, PLDI 2014
Country/TerritoryUnited Kingdom


  • Hoare-style verification
  • Software-defined networks


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