Wi-Fi Mesh Networking, What Is It and Why Do We Need It?

Mesh Networking

Mesh Networking

In attending trade shows and speaking with customers, I often get asked…

“Do you support Wi-Fi Mesh?”

It’s a Wi-Fi feature that gets a lot of marketing, especially with advent of consumer whole home Wi-Fi solutions (think Amazon Eero, Google Nest Wi-Fi, Linksys Velop, Netgear Orbi, TP-Link Deco, just to name a few). I find that commercial businesses don’t necessarily understand the nuances to how this technology actually works and thus it becomes this checkbox feature without any real thought on how it can bring value. In other cases, it gets confused with Cloud Managed Wi-Fi or Centralized Client Authentication, which are completely different things.

How Does It Work?

In a Wi-Fi Mesh network, there’s always at least one ROOT AP. The job of the ROOT AP is to provide a hard wired Ethernet connection back to your ROUTER.

Once there’s a ROOT AP in play, now you can have MESH APs. The role of a MESH AP is to create a wireless bridge back to a ROOT AP, thus creating a network connection that leads back to the router. Because of this, there’s no hard wired Ethernet connection needed to the MESH AP. So the value here is for the situation where you don’t have the ability to run Ethernet cabling but you still need to extend the Wi-Fi network to an area far away from the ROUTER. This also means you’re dedicating one radio to that wireless bridge job. Typically on a Dual-Radio Access Point (an AP that has one 2.4GHz radio and one 5GHz radio) the wireless bridge is the 5GHz radio which creates the largest bandwidth link available, while the 2.4GHz is used for Wi-Fi services for devices like mobile phones, tablets and laptops. More sophisticated Mesh implementations can even create bridges using both radios, or in Tri-Radio Access Points, all three radios. For simplicity, we’ll stick to Dual-Radio APs with one radio dedicated as the wireless bridge.

What are the benefits of Mesh?

The benefits of Mesh Networking completely depend on the design of the network. It’s not so simple that you can light it up anywhere and it “just works”. The best situation is when you have two or more ROOT APs that can connect to a MESH AP. This way, if for any reason a wireless bridge breaks, it’s got another backup path that it can take back to the ROUTER. The more MESH APs you light up, the more design is required to make sure the network is as reliable as possible.

What are the pitfalls of Mesh Networking?

Mesh Wi-Fi sounds promising on paper. The convenience of wireless links without the need for wires, what could go wrong? Well, a lot apparently. There are a few considerations when it comes to deploying Mesh APs.

1. Wireless Interference

A MESH AP is only as reliable as the wireless bridge back to the ROOT AP. This means it’s subject to any interference from other APs or from the environment itself. In an office, this could be easily be a microwave or just other employees testing their own Wi-Fi equipment. In most cases, it’s simply not possible for environment to be controlled so strictly, so your mileage will vary as the environment changes.

2. The Hidden Node Problem

This happens when MESH APs are connected to the same ROOT AP, but they can’t see or talk to each other. In this case A can talk to B, C can talk to B, but A and C cannot see each other. Because of this, A and C end up talking at the same time to B, which causes a lot of re-transmits, increasing traffic overhead and essentially slowing down the network. Imagine having one person on your far left and one person on your far right. They are both yelling at you at the same time. It would be difficult for you to process what they are both saying. And because they can’t see each other, they don’t know how to alternate speaking so it’s easier for you to hear them.

3. The Bandwidth Problem

Mesh is recommended not to go beyond one wireless bridge hop because with each hop beyond one, the total bandwidth is halved. Typically customers will want to light up MESH APs throughout the deployment without understanding that anything beyond one hop, the bandwidth starts suffering greatly. Compare this to a Gigabit Ethernet connection dedicated for each Access Point that isn’t subject to this problem and doesn’t suffer from interference from the environment.

So what’s the verdict?

In my opinion, Mesh Networking is great if you’ve got a very specific edge case that you can’t satisfy with Wired Networking. Otherwise, there are just too many variables to worry about, from proper network design to wireless interference, that prevents it from being a reliable option to use throughout your network. If you’ve got that one corner of the office building or otudoor parking lot that you just can’t get an Ethernet wire to, then give Mesh a try. Just don’t have any aspirations of having one ROOT AP and then scattering your environment with MESH APs and calling it a day.

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