Software Defined Networking (SDN) is a networking paradigm which proposed to decouple the forwarding and the control planes. Security and safety threat challenges at the control level are divided into the reinforcement of the controller, whatever the reason. This work aims to consider both threats and pave the way for a multi-controller architecture without East-West interface. Considering one nominal controller in charge of the data plane computation, we designed a second one in order to control the consistency of the decisions made by the controller, i.e. only through observing the activity of the command (i.e. the management traffic). Compared to related works, no direct exchanges between the controllers are required. The detection logic is introduced theoretically and it mainly relies on two phases: the learning of the decisions and the verification that each decision taken fits with the data plane estimate. The algorithm, implemented on ONOS, is discussed in a case study.