What are two general SDN characteristics?

A.	The separation of the control plane from the data plane.
B.	Northbound interfaces are open interfaces used between the control plane and the data plane.
C.	Southbound interfaces are interfaces used between the control plane and the data plane.
D.	OpenFlow is considered one of the first Northbound APIs used by SDN controllers.
E.	OVSDB is an application database management protocol.