Which two statements about northbound and southbound APIs are true? (Choose two.)

Question:
Which two statements about northbound and southbound APIs are true? (Choose two.)

• Only southbound APIs allow program control of the network.
• Only northbound APIs allow program control of the network.
• Only southbound API interfaces use a Service Abstraction Layer.
• Only northbound API interfaces use a Service Abstraction Layer.
• Both northbound and southbound API interfaces use a Service Abstraction Layer.
• Both northbound and southbound APIs allow program control of the network.

Explanation: A northbound interface is an interface that allows a particular component of a network to communicate with a higher-level component. Conversely, a southbound interface allows a particular network component to communicate with a lower-level component.

The northbound APIs on an SDN controller enable applications and orchestration systems to program the network and request services from it.

Southbound interfaces are implemented with a Service Abstraction Layer (SAL) Which speak to network devices using SNMP and CLI (Command Line Interface) of the elements that make up the network. The main functions of SAL are:
+ Expose device services and capabilities to apps
+ Determine how to fulfill requested service irrespective of the underlying protocol

Note:
+ An API is a method for one application (program) to exchange data with another application.
+ Interface here refers to the “software interface”, not the physical interfaces.

Exam with this question: CCNA v3.0 (200-125) Study Guide – Exam Dumps