WiFi has a natural tendency for clients farther away or clients at lower data rates to monopolize the airtime and slow down overall performance. Airtime fairness helps to improve the overall network performance in these conditions.
Airtime fairness has these characteristics:
- Only applies to downlink traffic.
- Can be set on both 2.4 GHz and 5 GHz radio bands.
- Can be set per-SSID. Each VAP is granted airtime according to the percentage assigned to the VAP.
- Can apply to all kinds of VAP (Bridge, Tunnel, or Mesh) and all kinds of authentication (Open, PSK, or Enterprise).
- Only applies to data and is not for control or management.
Airtime fairness is balanced from TX side from AP to client since that's the only direction under the control of AP.
Sample topology and usage
For example, there are two Bridge mode SSIDs with a wireless client and an airtime fairness weight of 80% and 20%. Using WaveDynamix to simulate the same traffic from Ethernet to the wireless client, the traffic for each SSID matches the airtime fairness weight assigned to them.
Airtime fairness is not related to SSID type or authentication type. In this example, it uses Bridge mode SSID and Open Authentication.
You must use the CLI to configure this function.
To set the airtime fairness weight in SSID:
atf-weight is 20 so there is no need to set this option for
config wireless-controller vap edit "atf_br1" set atf-weight 80 set ssid "atf_br1" set security open set local-bridging enable set schedule "always" next end config wireless-controller vap edit "atf_br2" set ssid "atf_br2" set security open set local-bridging enable set schedule "always" next end
To enable airtime fairness in radio:
This example uses one FAP-S423E unit with airtime fairness enabled on the 5 GHz radio band.
config wireless-controller wtp-profile edit "S423E_atf" config platform set type S423E end config radio-1 set mode disabled end config radio-2 set band 802.11ac set airtime-fairness enable set vap-all disable set vaps "atf_br1" "atf_br2" set channel "149" end set ext-info-enable enable next end config wireless-controller wtp edit "PS423E3X16000029" set admin enable set wtp-profile "S423E_atf" config radio-2 end next end
To verify the airtime fairness weight from FAP:
PS423E3X16000029 # cw_diag -c atf Airtime Fairness Info: interface ssid configured-atf applied-atf Radio 0 ATF disabled Radio 1 ATF enabled wlan10 atf_ssid1 80 80 wlan11 atf_ssid2 20 20 PS423E3X16000029 # wlanconfig wlan10 showatfinfo SHOW RADIO ATF TABLE WLAN:SSID/Client(MAC Address) Air time(%) Config ATF(%%) Assoc wlan10:atf_ssid1 80.0 80.0 wlan11:atf_ssid2 20.0 20.0 ------:Unallocated Airtime 0.0
Verify the airtime fairness weight from real traffic
Using WaveDynamix to create two same clients connected with two SSIDs, downlink traffic is passed from Ethernet to the wireless client with the same bit rate.
This example shows that
atf_br1 is almost four times higher than
To view traffic statistics from SSID1:
PS423E3X16000029 # cw_diag -d vap 90:6C:AC:8A:66:10 VAP extension info Radio 1 VAP 0: tx_packets : 60543 tx_bytes : 70608777 tx_data_packets : 60543 tx_data_bytes : 70608777 tx_datapyld_bytes : 68308143 tx_ucast_data_packets : 57462 tx_mbcast_data_packets : 3081 tx_discard : 94193
To view traffic statistics from SSID2:
PS423E3X16000029 # cw_diag -d vap 90:6C:AC:8A:66:11 VAP extension info Radio 1 VAP 1: tx_packets : 18839 tx_bytes : 19731946 tx_data_packets : 18839 tx_data_bytes : 19731946 tx_datapyld_bytes : 19016064 tx_ucast_data_packets : 15760 tx_mbcast_data_packets : 3079 tx_discard : 84924