Network technology was responsible for two of the most consequential technology epochs in the past 30 years, client-server and then Internet-centric computing, but it seems to have been playing catch up with events ever since. As online commerce, advertising and social networking changed consumer behavior, cloud computing and SaaS upended traditional models of IT. It often seems that networking is racing to keep pace with increasing demand, new usage scenarios and heightened security challenges. Fueled by the ability to decouple users of applications and data from the infrastructure providing them, nowhere are the winds of change blowing harder than in the WAN.
Once a low-performance appendage used to stitch together various data center and campus LANs, enterprise WANs have become the backbone of today’s digitally-transformed, highly-distributed and disintermediated business that is reliant on online processes, direct customer interactions and mobile, remote employees. Together, changes in business processes, customer expectations and organizational structure have placed enormous stress on traditional hub-and-spoke WAN topologies built on expensive, inflexible, leased line circuits designed for another era. Such is the confluence of business and technological changes that have laid the foundation for a new generation of software-defined WANs (SD-WAN) that is sweeping across enterprises and carriers alike.
SD-WAN is a means of controlling and managing multiple WAN circuits that uses the software-defined networking (SDN) technique of separating network data and control planes and a centralized, application-aware (L7) controller to manage traffic flows, routing policy, packet priority and network policy. SD-WAN works as a virtual overlay to any physical link (T-carrier, fiber, cable broadband, LTE, DSL, etc.) to create a logical path over multiple physical circuits. SD-WAN platforms replace traditional proprietary integrated HW-centric platforms with an open architecture.