Unexpected channel shifts from configured channels in Cisco APs

[roshney-roy]

Hi Experts,

We are using a licensed Cisco Catalyst 9800-CL Wireless Controller to manage our Cisco APs (models C9124AXE and AIR-AP1526E-Z-K9). According to our wireless network requirements, the channels on the APs are manually configured for both the bands(2.4 & 5 Ghz)

However, we are experiencing an issue where the AP channels are changing automatically despite the manual configuration. This is particularly noticeable with the 2.4 GHz channels, which tend to shift significantly.

We would appreciate any insights or suggestions on how to resolve this issue.

Thank you!

Regards,

Roshney Roy

[Rich R]

I suggest you go back to TAC in that case @roshney-roy 

CSCwj08558 is tagged as Unreproducible which means TAC were not able to reproduce it in their lab and the software development is not working on a fix for it.  Telling you to upgrade to 17.15.1 sounds like a wild shot in the dark hoping that that will fix it and I very much doubt that it will.  Also that bug only mentions 2.4GHz channels - nothing about 5 GHz channels.

I'll repeat Scott's question which you did not actually answer: Why do you need static channel allocations?

[roshney-roy]

Hi Rich R,

TAC updated the case today with a response that they do not have a fix at the moment(though the firmware upgrade was given as a solution few days ago). Developers are working to find a fix for the issue.

I had replied to Scott "Yes, it is a requirement at the access end of 2.4ghz to make the channel static. "

Hope to find a fix soon!!

[Rich R]

> I had replied to Scott "Yes, it is a requirement at the access end of 2.4ghz to make the channel static. "

That does not say why you have that requirement - just repeats that you have it.

[Gruntly101]

I am seeing this behavior as well (17.9.6, 9124AXE's, Mesh RAP/MAP). We need to custom set UNII-3 5ghz mesh backhaul channels and they shift channels randomly on reboot to non UNII-3 channels that are also disabled in DCA. Was TAC able to resolve your problem before I go down that path?

 

[roshney-roy]

Hi Gruntly 101,

TAC's final comment on this issue was that the disconnection of the APs from the WLC is forcing it to change its channel as this is how Cisco AP would behave in this scenario. Does your APs shift channel upon reboot or even during disconnections from the WLC (if it is connected to any). Please let me know your feedback

Regards,

Roshney Roy

[Gruntly101]

At this stage I have only experienced the channel change on reboot as these aren't yet in production. I cannot get them to hold a custom assigned channel after a reload. With DCA enabled they are still assigned a channel that isn't in the DCA channel list.

For example - Mesh tree as intended after setting custom channel assignments

Mesh tree after one RAP power cycled.

RAP initially prefers wireless backhaul rather than wired, taking on the channel of the other RAP. It transitions to wired sometime later but never changes back to custom channel, leaving two RAP's with identical channels.

Mesh tree after both RAP's power cycled simultaneously. All default to channel 100.

[Leo Laohoo]

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@roshney-roy wrote:
Cisco TAC has identified the bug "CSCwj08558" and has recommeded a firmware upgrade (17.15.1)

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Go back to Cisco TAC and get this case escalated to the BU &/or developers.  "upgrade to 17.X.X" is not an acceptable solution/workaround. 

Demand for an SMU or an APSP.