The control plane is the part of a network that carries signaling traffic and is responsible for routing. Control packets originate from or are destined for a router. Functions of the control plane include system configuration and management
The control plane, the data plane and the management plane are the three basic components of a telecommunications architecture. The control plane and management plane serve the data plane, which bears the traffic that the network exists to carry. The management plane, which carries administrative traffic, is considered a subset of the control plane.
In conventional networking, all three planes are implemented in the firmware of routers and switches. Software-defined networking (SDN) decouples the data and control planes, removes the control plane from network hardware and implements it in software instead, which enables programmatic access and, as a result, makes network administration much more flexible.
Moving the control plane to software allows dynamic access and administration. A network administrator can shape traffic from a centralized control console without having to touch individual switches. The administrator can change any network switch's rules when necessary -- prioritizing, de-prioritizing or even blocking specific types of packets with a very granular level of control.