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Case Study: During Radio Calibration, the AC Redelivers Channels and Transmit Power, Causing Intermittent Disconnection of STAs
Symptom
The STAs reconnect to the network after intermittent disconnection.
Relevant Alarms and Logs
None
Cause Analysis
During radio calibration, the AC redelivers channels and transmit power. As a result, STAs are intermittently disconnected.
Procedure
- Run the display station offline-record all command on the AC. The information "The VAP goes down because the configuration is modified." is found in the command output, indicating that STAs go offline because the configuration is modified and the VAP goes down.
[AC] display station offline-record all Rf/WLAN: Radio ID/WLAN ID ------------------------------------------------------------------------------------------------- STA MAC Device type Device ID Device name Rf/WLAN Last record time reason ------------------------------------------------------------------------------------------------- yyyy-yyyy-yyyy AP 11 x-x-x 1/1 2021-06-24/16:39:13 The VAP goes down because the configuration is modified. AP 2 x-x-x 1/1 2021-06-24/16:28:43 The VAP goes down because the configuration is modified. gggg-gggg-gggg AP 16 t-t-t 1/1 2021-06-24/16:13:43 The VAP goes down because the configuration is modified. AP 9 t-t-t 1/1 2021-06-24/15:49:13 The VAP goes down because the configuration is modified. AP 8 q-q-q 1/1 2021-06-24/15:12:40 The VAP goes down because the configuration is modified.
- Check the operation.log file to determine whether the VAP change operation is performed.
<AC> dir //The operation.log file exists. <AC> more operation.log //Check the modification operation on the AC based on the STA offline time range.
The check result shows that no VAP-related modification is performed when the STAs are offline.
- Check the radio calibration change.
- Run the display ap radio-reload-record all command to check whether there is any radio reloading record. No radio reloading record is found.
====================================================================== ===============display ap radio-reload-record all=============== ====================================================================== Info: This operation may take a few seconds. Please wait for a moment.done. ------------------------------------------------------------------------------------ AP ID MAC AP name Radio ID Reload time Reason ------------------------------------------------------------------------------------ 0 x-x-x x-x-x 1 2021-06-24/15:22:53 target assert 0 x-x-x x-x-x 0 2021-06-24/15:22:53 target assert 0 x-x-x x-x-x 1 2021-06-23/15:09:27 target assert
- Run the display channel switch-record all command to check whether channel switching occurs. Channel switching caused by radio calibration is found.
===================================================================== ===============display channel switch-record all=============== ===================================================================== OldCh/NewCh: Old channel/New channel OldBw/NewBw: Old bandwidth/New bandwidth RfID: Radio ID ------------------------------------------------------------------------------------------------------------------ AP ID AP name RfID OldCh/NewCh OldBw/NewBw Switch reason Switch time ------------------------------------------------------------------------------------------------------------------ 18 x-x-x 1 149/157 40M+/40M+ calibration 2021-06-24/16:39:13 6 t-t-t 1 44/36 40M+/40M+ calibration 2021-06-24/16:39:13 10 q-q-q 1 36/149 40M+/40M+ calibration 2021-06-24/16:39:13 24 z-z-z 1 52/149 40M+/40M+ calibration 2021-06-24/16:39:13
In conclusion, an exception causes the STAs to go offline because the channels are switched after radio calibration.
- Run the display ap radio-reload-record all command to check whether there is any radio reloading record. No radio reloading record is found.
- Change the default automatic radio calibration policy to scheduled radio calibration in the early morning, which prevents STAs from going offline unexpectedly due to radio calibration during working hours in the daytime.
For example, configure scheduled radio calibration to be performed at 02:30 a.m.
<AC> system-view [AC] wlan [AC-wlan-view] calibrate enable schedule time 02:30:00