A network communication system may include intelligent electronic devices (IEDs) in a ring communication network. A software-defined networking device may be programmed by a removable or disconnectable software-defined network (SDN) controller to control the flow path of data packets to the IEDs in the ring network. The software-defined networking device may inspect a data packet intended for a first IED to determine that the inspected data packet requests a responsive data packet from the first IED. A flow path failure may be identified based on a failure to detect a responsive data packet from the first IED within an expected response time.