Software Defined Networking has changed the way that organizations think about their network infrastructure.  Companies are looking at increasing automation of mundane tasks, orchestration of policy, and even using white box switches with the help of new unbound operating systems.  A new class of technologies that is coming to market hopes to reduce complexity and cost for the Achilles Heel of many enterprises: the Wide Area Network (WAN).

Do You WANt To Build A Snowman?

The WAN has always been a sore spot for enterprise networks.  It’s necessary to connect your organization to the world.  If you have remote sites or branch locations, it is critical for daily operations.  If you have an e-commerce footprint your WAN connection needs to be able to handle the generated traffic.  But good WAN connectivity costs money.  Lots of money.

WAN protocols are constantly being refined to come up with the fastest possible transmission and the highest possible uptime.  Frame Relay, Asynchronous Transfer Mode (ATM) and Multi-Protocol Label Switching (MPLS) are a succession of technologies that have shaped enterprise WAN connectivity for over a decade.  They have their strengths and weaknesses.  But it is difficult to build an enterprise WAN without one.

Some customers can’t get MPLS connectivity.  Or even Frame Relay for the matter.  Their locations are too remote or the cost of having the connection installed is far above the return on investment.  These customers are often forced to resort to consumer-class connections, like cable modems, Digital Subscriber Line (DSL), or even 4G/LTE modem uplinks.  While cheaper and easy to install, these solutions are often not as robust as their business-grade counterparts.  And when it comes to support on a down circuit…

Redefining the WAN

How does Software Defined WAN (SD-WAN) help?  SD-WAN technologies from companies like Silver Peak, CloudGenix, and Viptela function like overlay networks for the WAN.  They take the various inputs that you have, such as MPLS, cable, and 4G/LTE networks.  These inputs are then arranged in such a way as to allow you to intelligently program how traffic will behave on the links.  If you want only critical business traffic on the MPLS circuit during business hours you can do that.  If you want to ensure the 4G/LTE uplink is only used in the event of an emergency outage, you can do that too.  You can even program various costs and metrics into the system to help you make decisions about when a given link would be a better economic decision given the time of day or amount of transferred data.

You’re probably saying to yourself, “But I can do all of that today.” And you would be right. But all of this has to happen manually, or at the least require a lot of programming.  If you’ve ever tried to configure OER/PFR on a Cisco router you know what I’m talking about.  And that’s just one vendor’s equipment.  What if there are multiple devices in play?  How do you configure the edge routers for fifty sites?  What happens when a circuit goes down at 3 a.m.?  Having a simple interface for making decisions or even the ability to script actions based on inputs makes the system much more flexible and responsive.

It all comes down to a simple number for all parties involved.  For engineering, the amount of time spent configuring and maintaining complex WAN connectivity will be reduced.  Engineers love not needing to spend time on things.  For the decision makers (and bean counters), it all comes down to money.  SD-WAN technologies reduce costs by better utilizing existing infrastructure.  Eventually, their analysis can allow you to reduce or remove unnecessary connectivity.  That means more money in the pockets of the people that want the money.

Tom’s Take

I’ve referred to WAN applications as the “hello world” for SDN.  That’s because I saw so many people demoing them when SDN was first being talked about.  Cisco did this at Cisco Live 2012 in San Diego.  SD-WAN didn’t really become a concrete thing in my mind until is was the topic of discussion on the Spring ONUG meeting.  Those are the people with the money.  And they are looking at the cost savings and optimization from SD-WAN technologies.  You can better believe that the first wave of SD-WAN that you’ve seen in the last couple of months is just the precursor to a wider look at connectivity in general.  Better get ready to surf.