Which term describes employing traditional and SDN protocols to operate?

• A. Data Plane/Forwarding Plane
• B. SDN Overlay
• C. Open SDN
• D. Hybrid SDN

Answer: (D)

Hybrid SDN is the idea that a network can operate using both traditional, distributed routing and switching protocols alongside SDN-based control. In practice, some devices continue to run conventional protocols (like OSPF or BGP), while others are managed by an SDN controller using protocols such as OpenFlow. This coexistence lets an organization migrate gradually to SDN, gaining centralized control and programmability where desired, without rip-and-replace disruption. The other terms don’t capture this coexistence: the data plane describes where forwarding happens, not how control is implemented; an SDN overlay refers to a virtual network on top of existing infrastructure and doesn’t inherently imply using both traditional and SDN protocols; Open SDN isn’t a standard descriptive term for this approach.