Which API is typically used to enable communication between an SDN controller and the application plane?

Which API is typically used to enable communication between an SDN controller and the application plane?

• A. REST
• B. NETCONF
• C. OpenFlow
• D. OpFlex

Answer: (A)

The key idea here is how applications talk to the SDN controller—the northbound interface. REST is the typical choice because it uses HTTP, making it easy for applications written in any language to call the controller with standard operations (get, post, put, delete) and to exchange JSON payloads. This setup lets apps query network topology, push intents, and apply policies in a simple, scalable way, without needing specialized protocols or persistent connections. OpenFlow, by contrast, is the southbound protocol that the controller uses to communicate with the data plane switches, not with applications. NETCONF focuses on device configuration management rather than app-plane interaction, and OpFlex is a policy-distribution approach rather than the general app-to-controller interface. So REST best fits the role of enabling communication with the application plane.

The key idea here is how applications talk to the SDN controller—the northbound interface. REST is the typical choice because it uses HTTP, making it easy for applications written in any language to call the controller with standard operations (get, post, put, delete) and to exchange JSON payloads. This setup lets apps query network topology, push intents, and apply policies in a simple, scalable way, without needing specialized protocols or persistent connections. OpenFlow, by contrast, is the southbound protocol that the controller uses to communicate with the data plane switches, not with applications. NETCONF focuses on device configuration management rather than app-plane interaction, and OpFlex is a policy-distribution approach rather than the general app-to-controller interface. So REST best fits the role of enabling communication with the application plane.