The very heart of networking is about change. Your current network infrastructure is a platform on which the entire IT portfolio depends for communication and services. Although the network is made of many physical elements, such as routers, switches, and firewalls, it is for all practical purposes a single system. A change in any part of the network can cause a failure of the whole. This interdependence has led to a fear of change among network operators that prevents new services, new features, and even good operational practices.
SDN is a network architecture that changes how we design, manage, and operate the entire network so that changes to the network become practical and reliable.