SD-WAN
Software-Defined WAN — a virtual overlay that intelligently steers traffic across multiple WAN links.
SD-WAN (Software-Defined WAN) uses a centralized controller to apply application-aware routing policies across multiple underlay transports — broadband internet, MPLS, and LTE/5G — at once. The controller monitors link quality such as latency, jitter, and packet loss in real time, then steers traffic to the best path without reconfiguring each branch router by hand.
For the exam, contrast it with traditional WAN: a legacy MPLS-only WAN routes by destination IP, while SD-WAN routes by application identity and link health. Don’t conflate SD-WAN with SDN — SD-WAN applies software-defined principles to wide-area connectivity, whereas SDN broadly separates the control plane from the data plane across any network.
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