9800-40 WLC - Phantom clients

[Joshpre]

9800-40 WLC - Phantom clients

Hi Cisco Community support,

We're currently experiencing an issues with our 9800-40 WLC where the client count has excided 220k (2210 pages worth) clients. Only 13k of these are real users/devices which aren't experiencing any connectivity issues.

Has anyone experienced this before, cisco TAC appear to be struggling to find a solution?

WLC details:
IOS Ver: 17.9.4

TIA

[Rich R]

On AireOS and IOS these were what we called "stale client sessions".
I'm not seeing that at all on 17.9.4 so it must be something specific to do with your WLAN or client config.

1. What does CLI show? Do you see the same with "show wireless client summ"
Personally I rarely use the GUI - I do everything I can on CLI because it's quicker and I trust what I see on CLI more than GUI.  With GUI you're relying on the GUI to make a call to the WLC to get the data, and then format the data and display it, both of which are prone to bugs and errors in the code!

2. Check all the details for one of the stale clients: "show wireless client mac-address aabb.ccdd.eeff detail"

[Joshpre]

Thanks Rich,

To answer objectively:
1. The CLI reflects the correct amount of clients, no sign of the stale clients either.
2. The 'stale' clients do not present any client details... just empty client pages 

[Leo Laohoo]

Is the output the same across different browser?

[Joshpre]

Hi Leo,

This is the same across all browsers.

[Rich R]

So this sounds like a cosmetic issue with the GUI or a bug in the yang data which the GUI relies on.
You could check the yang data yourself by querying the client tables via restconf.
https://github.com/YangModels/yang/tree/main/vendor/cisco/xe/1791
I haven't checked the models myself but I expect you should find the data in one of:
Cisco-IOS-XE-wireless-client-global-oper.yang
Cisco-IOS-XE-wireless-client-oper.yang
If the yang data is correct then it's a bug in the GUI code - TAC should raise a bug to get it fixed.
If the yang data shows the same problem then it's a bug in the IOS-XE code which synchronises the yang data with the WLC - TAC should raise a bug to get it fixed.
This should be obvious to TAC but unfortunately the standard of 1st line TAC engineers these days is often shockingly bad!  We have complained to our account team about it.

I presume you have already checked your WLC config using the config analyzer (link below)?
And followed the best practice guidelines (link below) - particularly number of VTY required for GUI to work correctly?

[Joshpre]

Thanks Rich,

I'll put the YANG info to our TAC engineer and see if it's something they feel like running with.

Thanks for your help.

[Leo Laohoo]

This could be CSCwe74653.

[Rich R]

Good spot Leo but CSCwe74653 is supposed to be fixed in 17.9.4 - although it did take them a few attempts to get the problem fixed properly in the older code...

Incredible how so many of these old bugs are popping up again - almost as if they're making all the same mistakes in the code again!

[Leo Laohoo]

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@Rich R wrote:
almost as if they're making all the same mistakes in the code again!

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