topic Re: flapping on 5GHZ Channel in Wireless

flapping on 5GHZ Channel

HARA-123 — Mon, 23 Oct 2023 22:47:33 GMT

Hello Dear Expert

I have an issue after the last upgrade of the WLC

I have 8 access point cisco that brodcast different SSID : corporate, Guest and public

my problem is with the SSID corporate where I have bad BW , the line is a 300 mbps and when I perfrom a speed test I get only 35 mbps I checked the APS and I have found interferance on the 2.4Ghz with channel width of 20 Mhz , I have disabled the 2,4ghz on the corporate SSID and let only the 5GHZ but with 20 MHz on channel I get only 60 Mbps wihch a little better , once I move to 40 MHz( I have configured a RF policy with 40 mhz on channel widht ) I get the correct speed of 280 Mbps

the APS are installed on differents office on the same location

when I put the site under monitoring I found a bouncing on the opeation status of some APs not all of them , and when the opeartion status of 5GHZ is down the channel is moved to 20 MHz this bouncing affect the site connectivty and users can't see the SSID on their computer

Can you please help me to locate the issue , and undrestand Why the APs can't stay on 40Mhz channel widht

AP model :
cisco AIR-AP1852I-E-K9 ARMv7 Processor rev 0 (v7l) with 996240/631704K bytes of memory.
Processor board ID KWC24220DAP
AP Running Image : 17.9.4.27
Primary Boot Image : 17.9.4.27

WLC model : C9800-80-K9 version 17.9.4

I have attached a radioactive trace and show logging and also a screen of the Rf profile of one of the impacted access point

here is the load channel

FR000-WIFI-CTRL01#show ap dot11 5ghz load-info | i SE026
SE026-AP001 ac4a.56d0.6c40 1 13 0
SE026-AP005 ac4a.56d0.7560 1 1 0
SE026-AP006 ac4a.56d0.7600 1 7 0
SE026-AP004 ac4a.56d0.76c0 1 8 0
SE026-AP007 ac4a.56d0.77e0 1 8 0
SE026-AP008 ac4a.56d0.87a0 1 6 0
SE026-AP002 ac4a.56d0.8cc0 1 7 0
SE026-AP003 ac4a.56d3.df40 1 7 0

the POE configuration of switch where the AP is connected

interface 10
name "SE026-AP05"
power-over-ethernet critical
poe-allocate-by value
poe-value 30
poe-lldp-detect enabled
tagged vlan 30
untagged vlan 100
no snmp-server enable traps link-change
spanning-tree admin-edge-port
loop-protect

Your help is very appreciated

Thank you

Re: flapping on 5GHZ Channel

Leo Laohoo — Tue, 24 Oct 2023 01:33:12 GMT

Post the complete output to the following commands in a text file:

sh ap name <AP NAME> dot11 5ghz cleanair air-quality sh ap dot11 5ghz cleanair device type all

Re: flapping on 5GHZ Channel

HARA-123 — Tue, 24 Oct 2023 08:02:25 GMT

Hello Leo,

Thank you for your return

for the first command I get no output

FR000-WIFI-CTRL01#sh ap name SE026-AP001 dot11 5ghz cleanair air-quality
AQ = Air Quality

AP Name Channel Avg AQ Min AQ Interferers Spectrum AP Type
------------------------------------------------------------------------------

FR000-WIFI-CTRL01#sh ap name SE026-AP006 dot11 5ghz cleanair air-quality
AQ = Air Quality

AP Name Channel Avg AQ Min AQ Interferers Spectrum AP Type
------------------------------------------------------------------------------

this morning the operation status of 3 access point are down again

FR000-WIFI-CTRL01#show ap dot11 5ghz summary | i SE026
SE026-AP001 ac4a.56d0.6c40 1 Enabled Down 40 *4/8 (14 dBm) (108,112) REAP <==========
SE026-AP005 ac4a.56d0.7560 1 Enabled Down 40 *4/8 (14 dBm) (108,112)* REAP <=============
SE026-AP006 ac4a.56d0.7600 1 Enabled Up 40 3/7 (12 dBm) (44,48)* REAP
SE026-AP004 ac4a.56d0.76c0 1 Enabled Up 40 *4/8 (14 dBm) (108,112)* REAP
SE026-AP007 ac4a.56d0.77e0 1 Enabled Up 40 *4/8 (14 dBm) (108,112)* REAP
SE026-AP008 ac4a.56d0.87a0 1 Enabled Up 40 *4/8 (14 dBm) (108,112)* REAP
SE026-AP002 ac4a.56d0.8cc0 1 Enabled Up 40 *4/8 (14 dBm) (108,112)* REAP
SE026-AP003 ac4a.56d3.df40 1 Enabled Down 40 *4/8 (14 dBm) (136,132) REAP<===============

I have put on file the output of the second Cmd

Thank you for your help

Best regards

Re: flapping on 5GHZ Channel

Mark Elsen — Tue, 24 Oct 2023 11:31:05 GMT

- Always have a checkup validation of the C9800-80-K9 controller configuration with the CLI command show tech wireless
feed the output into https://cway.cisco.com/wireless-config-analyzer/
Consider this kind of a mandatory action when using 9800 controllers

As fas as AP behavior is concerned checkout : https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/217738-monitor-catalyst-9800-kpis-key-performa.html#anc4

Re: flapping on 5GHZ Channel

Leo Laohoo — Tue, 24 Oct 2023 11:33:13 GMT

What channels are allowed? I can see a lot of interference from UNII-2E and DFS channels.

Re: flapping on 5GHZ Channel

HARA-123 — Tue, 24 Oct 2023 14:33:16 GMT

Hello Leo

Thank you for your return

the channel width allowed are from 144 to 173 you can find attached the RF profile of the APs

Thank you

Re: flapping on 5GHZ Channel

Mark Elsen — Tue, 24 Oct 2023 15:40:29 GMT

- FYI : https://bst.cloudapps.cisco.com/bugsearch/bug/CSCwa08997

Re: flapping on 5GHZ Channel

HARA-123 — Tue, 24 Oct 2023 21:57:47 GMT

Hello Marce

I have checked the bug but no solution or workaround available

Re: flapping on 5GHZ Channel

Leo Laohoo — Tue, 24 Oct 2023 23:22:45 GMT

There is not enough channels to go around on 40 Mhz channel width.

Bring it down to 20 Mhz channel width and see if this makes any difference.

Re: flapping on 5GHZ Channel

Mark Elsen — Wed, 25 Oct 2023 06:09:13 GMT

>....I have checked the bug but no solution or workaround available
- Then you need to contact TAC and discuss it ,