Software-Defined WAN (SD-WAN)

Software-Defined WAN (SD-WAN) is a software-controlled approach to wide area networks in which a central control plane steers traffic between sites, data centers and cloud services over several connection types at the same time, such as broadband internet, mobile networks or MPLS.

SD-WAN separates control from data forwarding and places an encrypted overlay network over the existing lines. Policies are defined centrally and distributed to the edge devices at the sites. Core functions are application-aware routing, which prioritizes traffic according to the detected application, and dynamic path selection, which continuously measures the latency, jitter and packet loss of each line and automatically reroutes traffic when quality deteriorates. The industry association MEF has described SD-WAN services in the MEF 70 standard.

Compared with networks based exclusively on MPLS, SD-WAN frequently lowers line costs and accelerates the connection of new sites; it also enables Direct Internet Access (DIA) at every site. SD-WAN is operated in-house, as a managed service or as a cloud service. As the network layer, it is a component of Secure Access Service Edge (SASE), where it is combined with security services to form a SASE platform.