Software-Defined Wide Area Network (SD-WAN) is the implementation of SDN into WAN topology. The main idea behind SDN is to separate the control plane from the data plane. The network is managed from a centralized location from which network administrators can manage multiple devices in different geographical locations across the entire network. SD-WAN architecture, meanwhile, allows enterprises to use different links (MPLS, LTE etc.) across different branch offices. A centralized control plane allows you to configure policies that are then automatically applied to all sites. Additionally, you can configure more advanced algorithms to manage network traffic.
The advantages SD-WAN offers over a traditional WAN approach include reduced costs, increased application performance, more intelligent directing of traffic across the WAN, faster deployment and improved security.