What is the Rejecting Count on AP820-L(V3) for a Dual-band STA's 2.4 GHz Access Requests when the SSID is enabled with 5G-Prior Access?

5G-Prior Access, also known as Band Select on Enterprise APs, leads dual-band STAs to access the higher-capacity 5 GHz band to reduce the pressure on the 2.4 GHz band and improve user experience.

Dual-band STAs:

If the AP can receive the Probe Request frame from an STA both at the 2.4 GHz band and the 5 GHz band, this STA is identified as a dual-band STA.
If the AP can receive the Probe Request frame from this STA only at the 5 GHzb and, the AP learns that this STA is a 5 GHz STA.
If the AP can receive the Probe Request frame from this STA only at the 2.4 GHz band, the AP learns that this AP is a 2.4 GHz STA.

Controlling the Active Scanning Process to Discover WLANs:

The Band Select function always positively responds to 5 GHz Probe Requests, does not respond to 2.4 GHz Probe Requests sent bydual-band STAs, and responds to Probe Requests from inhibition STAs negatively. For example, when receiving multiple Probe Requests consecutively, the AP sends only one Probe Response.

For example, if the default value is 2, the STA performs scanning for two consecutive cycles before the AP sends a Probe Response frame.

Rejecting Accessing the 2.4 GHz Band:

After an STA discovers a WLAN for a user to access the WLAN, the STA sends an Authentication Request to the AP at first. Then, the AP sends an Authentication Response to permit or reject the STA's authentication request.

The Band Select function processes the Authentication Request. If the Authentication Request is sent by a dual-band STA at the 2.4 GHz band, the function can reject the Authentication Request until the dual-band STA sends an Authentication Request from the 5 GHz band. Thus, the STA is led to access the 5 GHz band.

Generally, when a dual-band STA searches for access, the STA sends one or more Authentication Requests at a band and waits for responses. If the STA does not receive responses or fails in access, the STA sends Authentication Requests at the other band and waits for responses. However, some dual-band STAs send Authentication Requests only at the 2.4 GHz.For high availability, you can use the Band Select function to set the rejecting count for a dual-band STA.

Assume that a dual-band STA sends Authentication Requests for M times before changing the band, and the rejecting count is set to N. If the dual-band STA attempts to access the 5 GHz band at first, the STA can access the 5 GHz band immediately. If the dual-band STA attempts to access the 2.4 GHz band at first, the STA can access the 5 GHz band only if N is equal to or greater than M; otherwise, the STA accesses the 2.4 GHz band. No matter which band a dual-band STA accesses, if the dual-band STA attempts to access the 2.4 GHz band at first, min (smaller one between M and N) Authentication Requests are rejected orignored.

As a result, the STA's access is delayed. The delay time depends onthe driver of the STA. For example, if the STA sends Authentication Requests atthe interval of 100 milliseconds and four Authentication Requests are ignored,the access of the STA will be delayed for 400 milliseconds.


Configuring the Rejecting Count for a Dual-band STA's 2.4 GHz Access Requests:

The default value of the rejecting count for adual-band STA's 2.4 GHz access requests is 2.

You may configure the rejecting count using the command below:


Ruijie(config)#band-selectaccess-denial value

value: specifies the rejecting count for adual-band STA's 2.4 GHz access requests, ranging from 0 to 10.


Note:

The more the rejecting count is, the more difficult the dual-band STA accesses the 2.4 GHz band, and the later the STA accesses the2.4 GHz band. On the other hand, the less the rejecting count is, the easier the dual-band STA accesses the 2.4 GHz band, and the sooner the STA accesses the 2.4 GHz band.

If many STAs fail in access or it takes a lot of time to access, configure this parameter to a smaller value or to 0.


Verification:

1. Run the "show running-config"command to check whether the Band Select function is enabled.
2. Run the "show band-select configuration"command to display parameters of the Band Select function.
3. After a period of running, run the "show band-select statistics" command to check the statistics.