What is the function of " off-the-shelf " switches in a controller-based network?

forwarding packets. In a controller-based network, ordinary forwarding devices still perform data-plane forwarding. The controller centralizes policy, management, and control decisions, but packets are still forwarded by the switches and routers in the infrastructure. Off-the-shelf switches do not provide the central view, do not normally make global routing policy decisions, and do not set the controller’s packet-handling policy. Cisco CCNA 200-301 v1.1 Automation and Programmability expects candidates to distinguish the data plane from the control and management planes. The corrected answer is forwarding packets. The controller tells the network what behavior is required, but the switch ASICs and interfaces continue to move frames and packets through the network. Confusing those roles is a common SDN misconception.