Which API is designed for communication between network applications and the controller?

Which API is designed for communication between network applications and the controller?

• A. Northbound API
• B. Southbound API
• C. REST API
• D. CLI

Answer: (A)

In software-defined networking, the interface from network applications to the controller is the northbound API. It provides a high-level, app-facing contract that lets programs request services, query topology and state, and push policies without worrying about how devices are implemented. The controller then translates those requests into actions on the underlying network via southbound interfaces to switches and routers. While REST is a common way to implement northbound communication, the essential concept is the direction and purpose of the interface: apps talking to the controller. The other option, a CLI, is a human-facing, command-line tool not intended for programmatic app-to-controller communication.

In software-defined networking, the interface from network applications to the controller is the northbound API. It provides a high-level, app-facing contract that lets programs request services, query topology and state, and push policies without worrying about how devices are implemented. The controller then translates those requests into actions on the underlying network via southbound interfaces to switches and routers. While REST is a common way to implement northbound communication, the essential concept is the direction and purpose of the interface: apps talking to the controller. The other option, a CLI, is a human-facing, command-line tool not intended for programmatic app-to-controller communication.