Software Defined Network

Software-defined Networking (SDN) is a new approach to designing, building and managing networks.. SDN allows network administrators to quickly and easily manage network services from a centralize location without having to manually configure each individual network element (switch/router). This is done through abstraction of lower layers functionality.
The basic concept of SDN is to make network control decisions from centralized location. This is done by decoupling and optimizing the system that makes switching/routing decisions and other control functions such as signalling (the control plane) from the underlying systems that forwards traffic to the selected destination (the data plane).