About Cisco Air Time Fairness

Cisco Air Time Fairness (ATF) for High Density Experience (HDX) allows network administrators to enable some groups to regulate downlink air time and configure some groups to receive traffic from the WLAN, more frequently than other groups. Therefore, some groups are entitled to more air time than other groups.

Cisco ATF establishes air time limits (defined as a percentage of total air time) and to allows administrators to apply those limits on a per SSID basis, where the SSID is used as a parameter to define a client group. Other parameters can be used as well to define groups of clients. Furthermore, a single air time limit (defined as a percentage of total air time) can be applied to individual clients.

If the air time limit for an SSID (or client) is exceeded, the packets that are in the downlink direction are dropped. Dropping downlink packets (AP to client) frees up air time whereas dropping uplink packets (client to AP) does not do anything to free up air time because the packet has already been transmitted over the air by the client.

Only air time in the downlink direction, that is AP to client, can be controlled accurately by the AP. Although air time in the uplink direction, that is client to AP, can be measured, it cannot be strictly controlled. Although the AP can constrain air time for packets that it sends to clients, the AP can only measure air time for packets that it hears from clients because it cannot strictly limit their air time.

What to do next:

• Configure Air Time Fairness Policies
• Configure Air Time Fairness Modes
• Monitor Air Time Fairness Statistics

 

 

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