SD-WAN – AKA A Three Stranded Cord Is Not Easily Broken

Many of us have heard the adage: “A Three Stranded Cord is Not Easily Broken.” Inherently, we understand that this is true. We see this demonstrated for example when we purchase rope: lots of strings intertwined. Over the years as the cords weaken, one may break but the rope still holds. With this basic explanation, you now understand SD-WAN.

Now let me explain a little further.

Whenever a new technology solution arrives on the scene it takes a while before its widespread adoption. Part of the reason is that new terms are created and blended with our existing vocabulary creating confusion. SD-WAN is a new technology born out of a recognition that one of the major expenses for many organizations is their bandwidth. Over the years numerous technologies have been introduced to reduce these costs:

MUXes
Voice over Frame-Relay
VoIP
WAN Optimizers

Just to name a few.

The carriers have also been trying to stretch and maximize their investments. For most of us the network has become a utility. We expect an always on network and use it constantly. Just look around, the proliferation of hand held mobile devices with a plethora of applications that allow non-stop communication, entertainment, and access to information (Maps, Google, Starbucks) has created a demand for bandwidth that is frankly challenging to meet. Each of the respective carriers is adding bandwidth daily. I work with a number of them and Time Warner, AT&T and others are laying fiber all over metropolitan areas. Private companies have cropped up that lay and sell both dark and lit fiber.

We also see that the cellular companies are adding and upgrading cell sites and working to partner with other cellular companies to exchange bandwidth. The appetite for bandwidth is so high that 3rd party companies are building cell sites and selling or renting them to the highest bidder.

Enough said, back to SDN-WAN.

This demand for higher amounts bandwidth is a challenge for most, if not all, organizations. Every CIO is faced with the need to increase the amount of bandwidth, while trying to maintain costs. IT Budgets are consistently flat and 80% of the IT budget is spent just maintaining the status quo. The reality of today is that the network IS a utility and if it goes down, most organizations come to a grinding halt. “All the while, of course, the IT department is expected to deliver value for money by minimizing capital expenditure and operational costs wherever possible.” My focus is the SDN over SPB, and while I seek to build secure, resilient, always on infrastructures that are easy to manage and deploy, eventually we have to leave the premise and traverse the WAN. Whenever I have to extend my network fabric over the WAN I am faced with the reality that the single MPLS pipe they pay for becomes my single point of failure. It doesn’t matter that my SDN network built on SPB has sub second failover, if that WAN link is the only link, my network is down. Those virtual servers and applications are cutoff from the users. I now bring in my carriers and help the customers to create a more resilient WAN.

Enter in SD WAN.

Talari and other companies have developed technologies and algorithms that allow the bonding together of multiple lower costs links from different carriers into a single, higher aggregate bandwidth pipe, that has higher availability and throughput than a traditional more expensive MPLS network. In addition, because we have spread the bandwidth over different medium (cable, fiber, G4, etc), and different companies, the failure of any one link does not bring the network down and is therefore more resilient. So, the adage: A three stranded cord… applies.

There are a number of organizations that are offering SD-WAN, and there are a number of great white papers available for those of you that would like to get a better understanding of what, how, who, etc. Most traditional router/WAN Optimize vendors have begun to develop products in this area, so make sure, when investigating them to do your research. I work with a number of carriers and they are starting to include this as part of their service. They provide multiple connections over different technologies and incorporate the SD-WAN service as a bundle. I suspect that this trend will become common place. It seems like a win-win to me. As with most technologies today, there are hosted and premise offerings and many include firewalls, etc. Make sure if you opt for a hosted solution, that behind the scenes, they are not creating a single point of failure. As always: Caveat Emptor a.k.a. get references.