A storage defined wide area network is a subset of the general software defined network concept. The WAN is no longer a single pipe; it's a fabric of multiple types of links, everything from 4G LTE to DSL to cable, and offers customers much more intelligence allowing them to prioritize traffic and apps based on policies. A software controller stands in for individual connections to the WAN allowing performance enhancements to be implemented such as; application bandwidth priority, measuring real-time performance in both directions across the WAN, implementing policies based on link types and usage, implementing protocol acceleration, data compression, and caching to improve application performance.
For example, a WAN might be used to connect branch offices to a central corporate network, or to connect data centers separated by distance. In the past, these WAN connections often used technology that required special proprietary hardware. The SD-WAN moves more of the network control into the “cloud,” using a software approach.