FortiAP - Features for high-density deployments

In wireless networks it is the client that decides what AP and band it connects to, and there are no standardized ways that a AP / Controller can force a client to connect to a different AP. To get around these challenges FortiAPs can be configured to deploy the following:

Enabling frequency band load-balancing

In a high-density environment is important to make the best use of the two WiFi bands, 2.4 GHz and 5 GHz. The 5 GHz band has more non-overlapping channels and receives less interference from non-WiFi devices, but not all devices support it. Clients that are capable of 5 GHz operation should be encouraged to use 5 GHz rather than the 2.4 GHz band.

To load-balance the WiFi bands, you enable Frequency Handoff in the FortiAP profile. In the FortiGate GUI, go to WiFi & Switch Controller > FortiAP Profiles and edit the relevant profile. Or, you can use the CLI:

config wireless-controller wtp-profile

edit FAP221C-default

config radio-1

set frequency-handoff enable

end

 

The FortiGate WiFi controller continuously performs a scan of all clients in the area and records their signal strength (RSSI) on each band. When Frequency Handoff is enabled, the AP does not reply to clients on the 2.4 GHz band that have sufficient signal strength on the 5 GHz band. These clients can associate only on the 5 GHz band. Devices that support only 2.4 GHz receive replies and associate with the AP on the 2.4 GHz band.

Setting the handoff RSSI threshold

The FortiAP applies load balancing to a client only if the client has a sufficient signal level on 5GHz. The minimum signal strength threshold is set in the FortiAP profile, but is accessible only through the CLI:

config wireless-controller wtp-profile

edit FAP221C-default

set handoff-rssi 25

end

 

handoff-rssi has a range of 20 to 30. RSSI is a relative measure. The higher the number, the stronger the signal.