Software-defined networking (SDN) is a mechanism that decouples a control plane from a network to manage the data plane of the network flexibly in a centralized view. In in-band-based software-defined wireless networks (IB-SDWNs), the control plane shares wireless channels with the data plane. As the amount of data-plane traffic increases, the interference from the data plane to the control plane becomes stronger, and the switches connected to the SDN controller via the control plane may become out-of-control. In this paper, we propose an interference management scheme that reduces the interference among control and data planes by adjusting the transmission rates of data-plane traffic in switches to ensure reliable connections between the SDN controller and switches. We implemented a prototype of an IB-SDWN and showed that the proposed interference management scheme ensures the reliability of control planes.