Which type of interface are OpenFlow and OpFlex?

In SDN architecture, southbound interfaces are APIs or protocols that sit between the control plane (SDN controller) and the data plane (network devices). OpenFlow is the most widely adopted open southbound protocol, and OpFlex - used in Cisco ACI - is a standards-based southbound protocol that uses a declarative policy model to communicate controller intent to network elements.

Eastbound interfaces refer to communication between peer controllers or orchestration systems of equivalent standing, not between a controller and data plane devices.

Cloud-bound is not a recognized category in the standard SDN interface taxonomy, which defines northbound, southbound, eastbound, and westbound interfaces.

Northbound interfaces connect the SDN controller to upper-layer applications and orchestration systems, not to the network forwarding devices that OpenFlow and OpFlex manage.