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Cisco Air Time Fairness (ATF) for High Density Experience (HDX) allows network administrators to group devices of a defined category and enables 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.
Allocates Wi-Fi air time for user groups or device categories
Air time fairness is defined by the network administrator and not by the network
Provides a simplified mechanism for allocating air time
Dynamically adapts to changing conditions in a WLAN
Enables a more efficient fulfillment of service-level agreements
Augments standards-based Wi-Fi QoS mechanisms
By enabling network administrators to define what fairness means within their environments with regard to the amount of on air time per client group, the amount of traffic is also controlled.
To control air time on a percentage basis, the air time, which includes both uplink and downlink transmissions of a client/SSID, is continuously measured.
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.
Cisco ATF establishes air time limits (defined as a percentage of total air time) and 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.
Cisco Aironet 1260 Series Access Points
Cisco Aironet 1260 Series Access Points
Cisco Aironet 1570 Series Access Points
Cisco Aironet 1700 Series Access Points
Cisco Aironet 2600 Series Access Points
Cisco Aironet 2700 Series Access Points
Cisco Aironet 3500 Series Access Points
Cisco Aironet 3600 Series Access Points
Cisco Aironet 3700 Series Access Points
![]() Note | Cisco ATF is supported only on Local and FlexConnect mode APs. |
Enforce air time based on configured policy
An AP can have multiple WLANs with multiple policies (1:16)
Strict Enforcement per WLAN—Air time used by the WLANs on a radio is strictly enforced up to the configured limits in the policies
Optimal Enforcement per WLAN—Share unused air time from other SSIDs
The sum of all policies should amount to 100 percent; there can be no oversubscription.
Public Hotspots (Stadium/Airport/Convention Center/Other)
In this instance a public network is sharing a WLAN between two (or more) service providers and the venue. Subscribers to each service provider can be grouped and each group can be allocated a certain percentage of air time.
Education
In this instance, a university is sharing a WLAN between students, faculty, and guests. The guest network can be further partitioned by service provider. Each group can be assigned a certain percentage of air time.
Enterprise/Hospitality/Retail
In this instance, the venue is sharing a WLAN between employees and guests. The guest network can be further partitioned by service provider. The guests could be sub-grouped by tier of service type with each subgroup being assigned a certain percentage of air time, for example a paid group is entitled to more air time than the free group.
Time Shared Managed Hotspot
In this instance, the business entity managing the hotspot, such as a service provider or an enterprise, can allocate and subsequently lease air time to other business entities.
Configure Cisco ATF at the network level (global) by entering these commands:
Configure Cisco ATF on a per AP group basis by entering these commands:
Configure Cisco ATF on a per AP radio basis by entering these commands:
Configure ATF policies by entering these commands:
Configure WLAN with a policy ID by entering this command:
Configure AP group-level override for Cisco ATF policy on a WLAN by entering these commands:
Configure AP-level override for Cisco ATF policy on a WLAN by entering these commands:
Monitor Cisco ATF configurations by entering these commands: