“As cloud use grows, WAN performance becomes critical to latency-sensitive and mission-critical workloads and inter-datacenter business continuity,” says Rohit Mehra, vice president of network infrastructure at IDC. “Accordingly, as enterprises plan and implement comprehensive cloud strategies, WAN architectures need to be considered in conjunction with datacenter infrastructure. Moreover, as enterprises move business processes to the cloud, there’s a greater need to fully integrate cloud-sourced services into WAN environments to ensure workload/application performance, availability, and security.”

 

Andrew Lerner of Gartner adds: “While many networking technologies are hyped as the next big thing, SD-WAN is delivering. In just three short years, adoption has taken off, with 6,000+ paying SD-WAN customers and more than 4,000 production implementations. We recommend SD-WAN when refreshing WAN edge equipment, renegotiating a carrier contract, building out new branches, or aggressively moving apps to the cloud (among other tasks).”

 

Agreement on a precise definition of an SD-WAN is difficult to find, but all SD-WAN implementations share the following features:

 

• Controllers, through which traffic policies are defined and pushed out to either virtual or physical appliances at each location
   

• Multiple data services, or endpoints, which virtualize the WAN, making multiple Internet services — such as xDSL, cable, and 4G/LTE — appear as a single network. Most SD-WANs also include MPLS
   

• Virtual overlays, meshes of secured tunnels formed across the multiple data services, allowing the SD-WAN to virtualize underlying data services
   

• Application-aware routing, algorithms that evaluate end-to-end performance, selecting the optimum path across the virtual overlay based on application requirements, business policies, and real-time network conditions

 

 

Unlike link bonders, SD-WANs aggregate and evaluate the full path, not just local-side connections. SD-WANs have more in common with traditional routers. In fact, many functions of “pure” SD-WANs can be replicated in routing. The biggest difference between the two technologies is usability: SD-WANs are delivered and deployed very easily, whereas routers require significant configuration.