There have been significant changes in wide-area networks over the past few years, none more important than software-defined WAN or SD-WAN, which is changing how network pros think about optimizing the use of connectivity that is as varied as Multiprotocol Label Switching (MPLS), frame relay and even DSL.
What is SD-WAN?
As the name states, software-defined wide-area networks use software to control the connectivity, management and services between data centers and remote branches or cloud instances. Like its bigger technology brother, software-defined networking, SD-WAN decouples the control plane from the data plane.
Thanks to Michael Cooney (see source)