<P> A centralized controller is used to set policies and prioritize traffic . The SD - WAN takes into account these policies and the availability of network bandwidth to route traffic . This helps ensure that application performance meets service level agreements (SLAs). </P> <P> SD - WAN consists of several technologies combined with newer enhancements . Redundant telecommunication links connecting remote sites date back to the 1970s with X. 25 links used for remote mainframe terminal access . Central management of those links with a greater focus on application delivery across the WAN started to become popular in the mid-2000s . SD - WAN combines the two, and adds the ability to dynamically share network bandwidth across the connection points . Additional enhancements include central controllers, integrated analytics and on - demand circuit provisioning, with some network intelligence based in the cloud, allowing centralized policy management and security . </P> <P> Networking publications started using the term SD - WAN to describe this new networking trend as early as 2014 . </P> <P> Research firm Gartner has defined an SD - WAN as having four required characteristics: </P>

Two flavors of dynamic software defined wan (sd-wan)