Which API enables communication between an SDN controller and network devices in the data plane?

Which API enables communication between an SDN controller and network devices in the data plane?

• A. Northbound API
• B. Overlay
• C. Southbound API
• D. Fabric

Answer: (C)

In SDN, the controller communicates with the devices that actually forward traffic (the data plane) through a southbound API. This interface lets the controller install flow rules, query status, and adjust forwarding behavior on switches and routers. OpenFlow is the classic example of a southbound protocol, though other options exist. Northbound APIs, by contrast, connect the controller to applications rather than to devices. Overlay networks describe virtual tunnels built on top of physical networks, and fabric refers to a network architecture, not the device-facing interface.

In SDN, the controller communicates with the devices that actually forward traffic (the data plane) through a southbound API. This interface lets the controller install flow rules, query status, and adjust forwarding behavior on switches and routers. OpenFlow is the classic example of a southbound protocol, though other options exist. Northbound APIs, by contrast, connect the controller to applications rather than to devices. Overlay networks describe virtual tunnels built on top of physical networks, and fabric refers to a network architecture, not the device-facing interface.