Death to the hybrid WAN

The continued use of hybrid WANs and SD-WANs add more confusion to the mix. It’s time we kill one of them.

Death to the hybrid WAN
aggi (CC0)

All too often SD-WAN and hybrid WAN are used interchangeably—mistakenly.

SD-WANs extend software-defined networking (SDN) technologies to the WAN. As with SDNs, SD-WANs build an “overlay” or a virtual abstraction of the underlying physical network that can then be reconfigured and optimized for the applications traveling across the overlay. It’s this property that allows SD-WANs to give one application a hub-and-spoke WAN configuration, while another application a meshed WAN configuration each with their own IP addressing spaces, traffic policies and more.

Hybrid WANs combine a mix of data services to interconnect geographically dispersed locations. A network that combines MPLS and carrier Ethernet services is a hybrid WAN, so too is a WAN that combines 4G and MPLS. When you have some sites connected via MPLS and others via IP VPNs, this too was a hybrid WAN. When you have sites connected to an MPLS backbone with a secondary Internet connection, you also have a hybrid WAN.

SD-WANs speak about the overlay; hybrid WANs speak about the underlay. The two are not exclusionary. You can build a hybrid WAN without an SD-WAN, and you could build an SD-WAN that’s a hybrid WAN.

Why not both SD-WAN and hybrid WAN?

You might be wondering, then, as to the difference between a hybrid WAN and a WAN. I would say, in fact, that practically there is no difference. I can’t think of any major MPLS deployment where my customer hasn’t had some other data service as well.  It’s what we called good old-fashioned WAN engineering with primary MPLS connections, backup or secondary internet connections, policy-based routing, and more. Practically, hybrid WANs are just another name for the WANs we’ve always delivered.  

Rather than continuing to use both hybrid WANs and SD-WANs, we should use the term that gets to the core value proposition distinguishing the new WAN. By this I mean the core value proposition of the SD-WAN: the ability to adapt to changing business needs, the ability to align routing with application and business requirements, and the flexibility to use any underlying infrastructure—and do all of this with a high degree of integration so that anyone can do node deployment.

I suppose some will want to call this whole thing “The New WAN” or “Next Generation WAN.” I’ll leave the rebranding work for others. But if I had to choose between hybrid WAN or SD-WAN, I know which would get my vote. We are called SD-WAN Experts after all.


Copyright © 2017 IDG Communications, Inc.

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