Symptoms
While deploying a number of 18xx/2802/3802 model access points (APs), which run AP-COS as their operating platform. It can be observed on some occasions that while many of their access points were able to join the fabric WLC without any issues. Some APs were not able to join the WLC and never even show under Monitor > Statistics > AP Join from the WLC UI.
The affected APs are not able to retrieve an IP address in the expected AP address pool specified from DNA Center, nor are there any CDP info displayed on the connected fabric edge (FE) switch.
Diagnosis
Determined that this particular fabric AP join issue was due to the following, prior CDP related bug on the AP-COS platform, as used by the 2802I model APs:
- CSCvd86274 Cisco 1800,2800,3800 Series AP does not send the platform value via CDP when it is brand new
Due to the above CDP issues with the AP-COS access points, the expected lightweight AP event macro was not applied to the switch port used by those APs fresh out of the box that have prior, affected software images installed from the factory. Those that had unaffected versions preloaded were able to join without issue to the fabric WLC without any intervention, given that both CDP and the smart port macros on the fabric edge nodes worked as expected.
Furthermore, when faced with this issue you may be unable to configure a static port for the affected APs, as the last-resort smart macro would then override any manual switch port configurations attempted on the fabric edge (FE) node that the APs were connected to.
Solution
To work around this issue, apply the following command for the switch port interface used by the APs affected, so that you can then manually assign the switch port on the FE to the correct VLAN intended for the access points:
FE-1(config-if)# no macro auto processing
This will allow the affected AP(s) to join the fabric WLC and download their new code from the WLC, which includes the CDP bug fix. Given that 8.5.x code or later is required to support SDA-Wireless, and CSCvd86274 has been fixed as of 8.5.103.0 and later.
Once the above workaround was implemented, we confirmed that the static port configs persisted once applied and that the affected APs were able to then join the WLC and download their new code. We were further able to then place the previously affected AP-COS access points on another port on the fabric edge node(s) and confirmed that the proper lightweight-AP event smart port macro was then applied, and that the APs are still able to join the fabric enabled WLC as a result.
You can then continue to use the workaround on the switch port using the "no macro auto processing" command, then once all APs are on the fixed version of code. You can thereafter remove the static configs - including the "no macro auto processing" config - and let the lightweight-AP event smart macros push the appropriate configs to the AP switch ports on the fabric edge nodes.
From there the APs are able to join the fabric WLC without issue, and operate within the SDA fabric as intended.
