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What SD-WAN architecture is best for your network?

When looking for the right SD-WAN architecture to implement, it's important to consider your specific network and the traffic it experiences.

Editor's note:  As software-defined WAN (SD-WAN) do-it-yourself and managed services continue to emerge, enterprises begin to wonder if a particular SD-WAN architecture will take the lead as the preferred design. In this podcast, ZK Research founder and principal analyst Zeus Kerravala addresses the issue of finding the right SD-WAN architecture to support your deployment.

Whether there is an optimal architecture for SD-WAN is an interesting question. The answer is really no, but here are a few points that can help you make the best decision for your environment.

It's important to note that flexibility is one of the main benefits of SD-WAN architecture. Traditional WANs were built with a single architectural model called a hub and spoke that everybody had to use. In a hub-and-spoke network design, all critical services were deployed in the data center or the hub, and all branches connected over the WAN link or the spokes. This meant all traffic went through the hub, and bandwidth was used inefficiently because backup connections could only activate if the primary network failed. In a sense, businesses were paying for twice the bandwidth they really needed. While not optimal, this method worked OK, because critical resources like applications and data were in the company data center, which the network was optimized for. 

Now fast forward to today. It's about 30 years since this architecture was developed, and everything has changed. We have far more use of cloud and peer-to-peer traffic, which is driving the need for a different type of SD-WAN architecture. There's a higher level of direct internet traffic and mesh traffic resulting from cloud and peer-to-peer use. This makes the environment much more complicated, as there are more connections to be made.

Luckily, most SD-WAN options can be managed from a centralized GUI (graphical user interface), instead of managing everything from a command line and touching every box. Also, things like meshing can be done dynamically. For example, let's say you have two people in two different branches wanting to make a video call. Historically, all traffic would go through the spokes, through the hub and back up the other spoke. That was an inefficient way to do it. Now, you can set up a policy that states, "If I'm making a video call, dynamically create a tunnel between the two locations, and once the video call is done, tear it down." 

We are not architecturally setting up a fully meshed network, but we're setting up the capability to automate the mesh connections when we need them. So for questions about what architecture that best supports an SD-WAN deployment or what's the best SD-WAN architecture, there really is no best architecture, per se; every organization is going to be different.

The key to choosing an SD-WAN architecture

The key is to understand what WAN traffic patterns look like. For example, consider cloud traffic volume, or how much voice, video, branch-to-branch, peer-to-peer or mobile traffic  you have. Then use those traffic patterns to build the optimal architecture for your enterprise. Again, that architecture is going to change over time. So, you want the ability to be able to manage centrally and dynamically create automated network policies. Keep in mind, you need to watch how traffic changes and adjust accordingly. It's probably a good idea to study traffic patterns quarterly. 

As you go about architecting your network, understand it is going to change, and really, no matter how you architect it today, there is no right answer. But if you have the right policies and the right dynamic network connections being created, then the architecture, in a way, will follow the applications. That's ultimately what you want. 

Next Steps

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This was last published in October 2016

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