Definition
Software-defined networking (SDN) is an approach to network management that decouples the network control and forwarding functions, enabling network control to become directly programmable and the underlying infrastructure to be abstracted from applications and network services. It separates the network's control plane from its data plane, allowing for centralized management and programmability of network devices. This separation simplifies network configuration, management, and automation, making networks more agile and responsive to changing business needs. For instance, SDN allows for dynamic traffic routing and policy enforcement based on real-time application demands, a significant improvement over traditional static configurations. Unlike traditional networks where control logic is distributed across individual devices, SDN centralizes this intelligence in a controller. Understanding SDN is crucial for network professionals and appears on certifications like the CISSP and CCSP, as well as in advanced networking courses.