The purpose of this FAQ is to address some of the most common questions and misconceptions that keep coming up in roaming related discussions.
WLAN Roaming FAQ
What is roaming?
Simply put, roaming is the act or process by which a client device transitions from one cell (BSS) to another.
Is roaming a feature of the infrastructure (APs, controller, etc.)?
No. In the 802.11 standard (a.k.a Wi-Fi), roaming decisions are left to the client device and does not specify any criteria for determining when and where to roam to. All the wireless infrastructure can do is leverage standards-based and/or proprietary mechanisms to try to influence client device roaming behavior and maybe provide for reduced roaming times. But that doesn’t always work well.
How does a client device decides when and where to roam?
Different vendors use different criteria differently. Most of them take into account received signal strength, data rates (PHY rates), frame retry rates, and other metrics in their roaming algorithms. More often than not, roaming criteria isn’t properly documented if at all. In the consumer space, iOS devices are the best documented ones.