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Airtime Fairness Reservation Mode

Airtime Fairness Reservation Mode

I want to use the new airtime fairness reservation mode because it appears to solve the problem of giving a production paid for WLAN priority over a free public WLAN that exists in the same physical space. Our APs are all 3825s and 3935s. While working on configuring this new feature I came across this line in the help section:

"If a WLAN service with Airtime Reservation is associated to a radio, the QCA ATF module is turned on, and the AP will restart in order to load the ATF module. The number of clients supported by QCA ATF is 50"

Does this mean that if we use this feature the AP client limit is reduced to 50 per radio? Our deployment is a convention centre where we frequently have APs servicing upwards of 100 clients per radio. Should this option be used in a high density environment?
Does the restriction also apply to the legacy airtime fairness?

Honored Contributor
Is there a whitepaper available - I'd like to read more about it so I'd unterstand where this 2% are coming from.


Extreme Employee
Airtime Reservation is the updated version of Flexible Client Access.

To configure on Ap37xx or earlier APs, you need to select the VNS->Global->Wireless QoS->Fairness Policy, and then check the VNS->wlan->QoS->Flexible Client Access checkbox. It behaves as before, and there is no limit on the number of users per radio.

To configure on the Ap38xx/AP39xx , you need to select the VNS->Global->Wireless QoS->Wlan Airtime Reservation Configuration. Can configure up to 4 wlans, and the wlans obviously have to be assigned to the ap radios. This new feature does allow you to prioritize up to 4 wlans above the others. It is still good to use policy rules to mark and prioritize the traffic from the wireless onto the wired network. If one of these wlans is assigned to an APs radio, then there will be a limit of 50 clients per radio. It is not a strict limit, ie more clients could connect, but the performance would become very poor. The feature is assigning a percentage of the airtime to every client connected. The granularity of 100% dictates that 2% is the smallest that can be given to one client, hence 100/2 = 50 limit. Thus it is good to enforce a strict limit on the number of clients per radio. This can be configured under Load Groups and to configure a strict limit for the specific radios.

So for your needs, it sounds like using this might not work, unless you feel confident you would have enough aps to implement the 50 user maximum.