SD-WAN is the abbreviation of software defined wide area network. It is an application example of SDN technology in wide area network. The core of sd-wan is to allow users to manage the bandwidth of wide area network intelligently by themselves. By using SDN technology to abstract and decouple the control function and data forwarding function of network equipment, users can independently control the flow direction of WAN traffic according to the predetermined routing strategy, integrate MPLS, special line, optical fiber, Internet, LTE and other network line resources for WAN traffic scheduling, so as to achieve the effective use of Wan resources and better protect the users' business-related interests Key applications.