What is a WAN?

By Greg BryanMar 7, 2024


Welcome back to TeleGeography Explains the Internet. We've reached the finale of our five-part series that makes good on our name, literally explaining the ins and outs of the interwebs.

Over the past five weeks, we've endeavored to explain precisely how data moves around the world, covering the basics of internet, transport networks, data centers, and the cloud along the way.

Today we answer the lingering question: What is a WAN?

First, let's get definitions out of the way.

WAN stands for wide area network, which came out of the term LAN, or local area network.

Older gamers might recall LAN parties. To play against one another, you'd physically bring PCs into a room and connect them with Cat6 cables. The WAN is the same idea, but wires span much larger distances, traversing the globe.

The original private WANs were related to something we already discussed: the on-premises data center.

When corporations started moving toward digital transformation— making all kinds of business processes computer-based instead of analog—they needed to connect certain offices to the data centers set up in larger headquarters or campuses.

At first, this was primarily a network of private lines, like those we discussed in the transport networks episode. The upshot is just like it sounds: a corporation would reserve a line on a carrier’s network that belonged entirely to them for a defined amount of bandwidth.

Back then, it was usually what we called “protected service,” meaning the private line was a ring rather than a single line so that it could be self-healing if there was a fault. A corporation would lease a private line, back then often SONET or SDH, from a carrier to directly connect an office to a data center site they owned.

This was often a hub-and-spoke setup with all lines converging on the sites with the data center. So, for example, a company would purchase private lines from their key offices in North America back to headquarters in NYC. Then perhaps they'd do the same thing with European offices back to an HQ in Paris or Frankfurt. The advantage here is that these leased lines belonged entirely to that corporation, so they were secure, protected, and did not get involved in the traffic jams of the public internet.

Eventually, the digitization of the corporation became complete enough that they needed many such lines in redundant connections to allow data to flow between the offices themselves rather than route through the HQ or DC sites and then back out. As you can imagine, redundant private lines between all offices can not only grow exponentially in number, but also become prohibitively expensive.

But this is just the beginning of the story.

Listen below to brush up on the evolution of the WAN and hear from my colleague Brianna Boudreau, TeleGeography's current SD-WAN guru.

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From This Episode:

Greg Bryan

Greg Bryan

Greg is Senior Manager, Enterprise Research at TeleGeography. He's spent the last decade and a half at TeleGeography developing many of our pricing products and reports about enterprise networks. He is a frequent speaker at conferences about corporate wide area networks and enterprise telecom services. He also hosts our podcast, TeleGeography Explains the Internet.

Connect with Greg  

Brianna Boudreau

Brianna Boudreau

Senior Research Manager Brianna Boudreau joined TeleGeography in 2008. She specializes in pricing and market analysis for wholesale and enterprise network services with a regional focus on Asia and Oceania. While at TeleGeography, Brianna has helped develop and launch several new lines of research, including our Cloud and WAN Research Service.

Connect with Brianna