Various communication channels and protocols

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SD-WAN is an implementation of the SDN approach to WAN. A global (or distributed, as the word wide is also translated in the combination wide area network) network is characterized by the breadth of geographic coverage, unlike a local area network (LAN), and can cover entire regions, cities and even countries. Strictly speaking, the global (still) Internet itself is ultimately a WAN. Commercial enterprises, state or municipal institutions also often build their own WANs of various sizes - depending on the ramifications of their branch structure.

are used to connect individual WAN fragments. X.25, frame relay, analog modem lines, xDSL, MPLS, copper and fiber optic cables — specialists creating and servicing WANs have to deal with all of this. It seems completely logical to transfer traffic management in such a network to an automated system that will be able to greece whatsapp data and build the optimal virtual channel on the existing WAN infrastructure at any time for each connection and for each type of data. This is how SD-WANs arise — solutions for network management and data transfer between the center and branches.

Of course, the convenience and ease of administration of a distributed network is a good thing, but a business would hardly invest in SD-WAN development just to reduce the load on IT departments of organizations with many branches. The impetus for the development of this concept was the growing popularity of SaaS (software as a service).

To effectively replace a local application with a cloud application, it is necessary that the user on-site does not feel any difference between interacting with some software on his computer, on a LAN server in the next room, and on a virtual machine deployed in a commercial data center tens of kilometers away. This need has given rise to the practice of concluding service-level agreements (SLA) between providers and consumers of cloud services, which guarantee the maintenance of clearly measurable connection parameters (signal delays, packet losses in the communication channel, delay variations, etc.) over a certain period of time during the service interval (say, 99.99% of the time during a month).