Cloud computing plays a vital role in managing and processing the diverse data generated by Internet of Things (IoT) devices, creating the cloud-IoT (CIoT) architecture. However, CIoT is insufficient for applications that are latency-sensitive and require significant network bandwidth. To address these challenges, fog computing complements CIoT, forming a distributed architecture called the Fog-IoT architecture. The diverse nature of Fog resources complicates the management of interoperability and scalability within the Fog-IoT architecture. Software Defined Network has been proposed as a solution in managing interoperability and heterogeneous resources in distributed architectures. This paper evaluates two software-defined network (SDN) east-west interfaces - the Modified Communication Interface for Distributed Control Plane (mCIDC) and the Distributed SDN Framework (DSF), in addressing the challenges of manageability and interoperability in Fog-IoT architecture. Experiments conducted using the SDN Floodlight controller indicated that mCIDC required more packets for inter-controller communication compared to DSF, with average captured TCP packets of 26,330.7 and 17,473.1, respectively. The DSF exhibited lower inter-controller communication overload (ICO) with an average ICO of 222.6, compared to 301.2 for mCIDC. Additionally, the DSF generated fewer errors than mCIDC, with average TCP errors of 2,713.4 and 3,935.8, respectively. The results show that DSF uses fewer packets and generates fewer errors during inter-controller communication, making it more reliable than mCIDC for Fog-IoT architecture.