What does an SDN controller use as a communication protocol to relay forwarding changes to a southbound API?
Correct Answer: A
Southbound APIs facilitate control over the network and enable the SDN Controller to dynamically make changes according to real-time demands and needs.
OpenFlow, which was developed by the Open Networking Foundation (ONF), is the first and probably most well-known southbound interface. OpenFlow defines the way the SDN Controller should interact with the forwarding plane to make adjustments to the network, so it can better adapt to changing business requirements. With OpenFlow, entries can be added and removed to the internal flow-table of switches and routers to make the network more responsive to real-time traffic demands.