A software-defined wide-area network (SD-WAN), is a network that is abstracted from its hardware, creating a virtualized network overlay. Operators can remotely manage and quickly scale this overlay, which can span over large geographical distances. It is an application of software-defined networking (SDN).
An SD-WAN can connect several branch locations to a central hub office or cover multiple locations in a large campus such as a university campus. Because it is abstracted from hardware, it is more flexible and available than a standard WAN. It relies on four central components: