People often use the terms “hybrid WAN” and “SD-WAN” interchangeably – and that’s a mistake. Hybrid WANs deal with the underlay; SD-WANs deal with the overlay. And the two aren’t mutually exclusive, either: You can build an SD-WAN that’s also a hybrid WAN, and you can build a hybrid WAN without an SD-WAN.
Hybrid WANs interconnect locations with a combination of at least two data services. Mixing MPLS and carrier Ethernet services forms a hybrid WAN so too does MPLS and 4G. The common usage of hybrid WANs refers to interconnecting locations with MPLS and some kind of Internet connection, such as xDSL, cable, or 4G. But in all cases there’s a mix of two types of data services that connect locations.
On the other hand, SD-WAN solutions build a virtual abstraction overlaying data services. This overlay can be reconfigured and optimized for each application traveling across it. The same SD-WAN solution can allow one application to use a meshed WAN, which provides individual IP addressing spaces and traffic policies, while providing another application with a hub-and-spoke configuration.
What’s Wrong With Using Both Terms?
Using both terms is a nice idea, but in reality, a “regular” WAN is really a hybrid WAN. Customers who use MPLS deployment usually have other data services as well; though their WAN is engineered to provide primary MPLS connections, they are also provided with secondary or backup connections, as well as policy-based routing. So really, WAN is just another name for hybrid WAN.
It’s logical, therefore, to use the term SD-WAN instead of hybrid WAN. In essence, the term “SD-WAN” is a term which distinguishes the “new” WAN from the “old” WAN/ hybrid WAN. Of course, another solution would be to call SD-WAN the “New WAN” or “Next Generation WAN” – but that’s already rebranding.
Offering a high degree of integration, SD-WAN provides the flexibility to use any existing underlying infrastructure, and its easy installment allows almost anyone to do the node deployment. It also provides users with the ability to align routing with application and business requirements and to adapt to changing business needs.
At the end of the day, if we need to choose one term over the other, choosing “SD-WAN” makes a lot more sense. But maybe we’re biased. After all, we *are* called SD-WAN Experts.