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Wi-Fi means mobility. Devices that can move around and be free of all that pesky cabling. Roaming, the ability for a device to move from one AP to another, is critical. There is nothing more frustrating than sitting underneath an AP—you can see it, the AP is right there—but you aren’t getting a strong signal. What to do?
How Wi-Fi Roaming Works
First, let’s address a common misconception: who tells a Wi-Fi device to roam? Most people will say the AP. In fact, the device decides and there is very little the AP—or any other device—can do about it.
Usually, the client stays connected to its AP until the signal strength drops and becomes too low. How low? Well, that’s up to the device. And all devices are a little bit different. A few allow you to adjust the roaming threshold setting, but most do not. A client device that should roam but doesn’t is known as a sticky client.
But you’re still here, standing under an AP with a device reporting a low signal. How do you get that stubborn thing to roam?
Fortunately, there are some tricks available. The first is a standards-based method that tells the device about the network and helps it make a better decision. The IEEE 802.11k standard allows a device to ask an AP about the network, including how well the AP can hear it, and vice versa. It can even get a list of neighboring APs instead of having to scan for itself. Kind of like using a dating service versus going to a bar to meet someone new! More importantly, it gives the device a much better idea of whether it’s time to move on or stick with its current AP.
Another standard, 802.11v, allows an AP to request--politely—that the device move and even give a list of suggested APs the device could move to. Sounds great!
The downside to both of these is that the AP and the device each need to support the standard. Some do, but not all.
We mentioned that roaming—the decision by a device to disconnect from an AP and connect to a new one—is a device decision. But there is a way that an AP can “force” a device to move: it can send a de-authentication message that disconnects the device. Of course, the device will automatically try to reconnect. As part of the reconnection process, it scans its surroundings and—Egad! I’m right under an AP!—and connect to the closer AP.
All Ruckus APs support this. As a matter of fact, we combine this concept of forcing a device to move along with some other intelligence around exactly when to use it, plus standards like 802.11k and 802.11r. We call it SmartRoam+. You can call it helping Wi-Fi devices roam more quickly and seamlessly.
There’s a lot more to device roaming and we’ll save that for another post. But in the meantime, you can use this to get your “stuck” devices moving again.