Formal Modeling and Systematic Black-Box Testing of SDN Data Plane

Existing tools for Software-Defined Networking (SDN) data plane testing can be classified into two classes: white box and black-box. For the former, all or part of source codes should be accessed. But for testers outside the manufacturers, the accessing of source code is impossible or very difficult in most cases, especially for hardware devices. For the latter, test cases are manually developed, which cannot ensure the coverage. In this paper, we present a model based black-box systematic testing method for SDN data plane. We propose a new model, Pipelined Extended Finite State Machine (Pi-EFSM), to specify the multiple-level pipeline of SDN data plane. For the Pi-EFSM model, we present a 3-phase systematic test generation approach. By using a hierarchical test generation strategy, the proposed test generation method can alleviate state space explosion to some extent. Our test generation method can achieve the systematic coverage towards the elements of the model. We apply our method in the testing of Open Flow switches (specification version 1.3.0). We build a Pi-EFSM model for Open Flow switches and derive the executable test sequences. Some implementation faults and specification confusions are exposed when we test two switches, Open switch 2.1.0 and CPqD Open Flow 1.3 Software Switch.