topic APs Cannot join the Controller in Wireless

APs Cannot join the Controller

Allan001 — Thu, 23 Mar 2023 16:35:58 GMT

Hi all,

My APs can't join the C9800-CL ver 17.6.5. The controller is run on a HyperV server.

1) Certificate is configured, and I see it with: sh wireless management trustpoint.

2) I configured the DHCP scope in the controller

3) Checking the DHCP binding - it shows that 2 APs have been allocated addresses, and I can ping those 2 APs from the controller. However, the APs are not joining the controller.

4) Wireless management is an SVI in controller under VLAN 10

5) Gig 2 is configured as a trunk, and VLAN is allowed on Gig2

6) The port-facing APs are configured as access with VLAN 10

Additionally, I haven't registered the controller with a license yet, so I'm uncertain whether it's necessary to do so for the APs to join. The AP model is C9115xai. In the logs, I cannot see any CAPWAP log. And to register the AP license to the controller using a smart account. I noticed some IP addresses need to be configured for the controller to communicate with CCSM - where would I get those IP addresses?

Any help is appreciated.

Thank you,

Re: APs Cannot join the Controller

balaji.bandi — Thu, 23 Mar 2023 16:39:32 GMT

C9115xa - what version of AP ? new model v5 or more need Cat 9800 should be 17.8.X or 17.9.X

Also post complete log from AP console.

Re: APs Cannot join the Controller

Mark Elsen — Thu, 23 Mar 2023 16:53:28 GMT

- Check controller configuration with show tech wireless (CLI command) and feed that output into : https://cway.cisco.com/wireless-config-analyzer/ , check AP model and verify if this FN might be applicable : https://www.cisco.com/c/en/us/support/docs/field-notices/724/fn72424.html , for Cloud controller AIR-DNA license for APs is mandatory.

Also check controller logs when the APs try to join , advised too : check AP boot process with console attached, check for errors if any.

Re: APs Cannot join the Controller

Scott Fella — Thu, 23 Mar 2023 17:41:21 GMT

First off... make sure you follow the guide and you have met the requirements for the size of the controller. Also, when using a 9800-CL, you really don't want traffic to tunnel back. You wan to setup the management and the wireless management which I usually use the management also as the WMI. License is not an issue here because you probably purchased the license when you bought the ap... tied to the ap. Place the ap on the same subnet as the controller management to at least validate if the ap can join. Then you can move the ap to any other subnet and you don't have to create any new SVI on the controller.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/9800/9800-cloud/installation/b-c9800-cl-install-guide/b-c9800-cl-install-guide_chapter_01011.html

You can also search the internet for "cisco 9800-CL Hyper-V" and look at blogs and or videos on the setup.

Re: APs Cannot join the Controller

Mark Elsen — Thu, 23 Mar 2023 18:14:21 GMT

- Adding to my initial reply , if problems persist then start using these tools too : https://logadvisor.cisco.com/logadvisor/wireless/9800/9800APJoin

Re: APs Cannot join the Controller

Allan001 — Thu, 23 Mar 2023 21:15:08 GMT

Hi Balaji,

I really appreciate your taking the time to respond. The APs are at a remote site - I will get a tech to drive to the site tomorrow to console into the AP. I also asked the customer to check the UDP ports 5246 & 5247 are not blocked on the the FW. I found out that there is an FW in between the controllers and the switches with APs. Once I have the AP console output tomorrow, I will share it here

Thank you

Re: APs Cannot join the Controller

Allan001 — Thu, 23 Mar 2023 21:18:27 GMT

Hi Marce,

Many thanks for providing solutions. Much appreciated. I will try the solutions you provided above. Once again, thank you for your time and effort in trying to help.

Thank you

Re: APs Cannot join the Controller

Allan001 — Thu, 23 Mar 2023 21:26:14 GMT

Hi Scott,

Thank you so much for your contributions. I really appreciate it. Currently, the APs are placed in the same vlan as the management. When configuring the controller, I used a cisco guide on deploying the C9800-CL on a HyperV. I am not sure what I am missing. I also watched youtube videos, and it looks like I configured the exact same config. The difference is mine is not working.

Once again thank you so much.

Re: APs Cannot join the Controller

Allan001 — Thu, 23 Mar 2023 21:27:30 GMT

Hi Marce,

Thank you again. I will go through these docs.

Re: APs Cannot join the Controller

Scott Fella — Fri, 24 Mar 2023 01:05:12 GMT

Console into the ap and attach that to the thread. That should show a message why the ap con't join the controller.

Re: APs Cannot join the Controller

balaji.bandi — Fri, 24 Mar 2023 07:44:23 GMT

Sure get the information so we can assist better.

Re: APs Cannot join the Controller

Allan001 — Fri, 24 Mar 2023 09:04:56 GMT

Hi Scott,

I will get a tech to go to the site and share the output.

Thank you.

Re: APs Cannot join the Controller

Scott Fella — Fri, 24 Mar 2023 14:36:47 GMT

@Allan001 a couple of things also. I would configure the DHCP on the controller, ip helper should be on the SVI on the upstream L3 device and you should use an external DHCP server that all other devices use to obtain an ip address. Also it doesn't hurt to register the controller to the Smartlicense portal, it only take a few minutes as long as the Smartlicense is in your portal.

Make sure the tech captures this from a few ap's also and you should check to make sure the switch port is configured properly so that the ap is on the management/wireless management vlan. Doesn't hurt to provide the port configuration also, so that others can review and provide feedback.

Re: APs Cannot join the Controller

Allan001 — Fri, 24 Mar 2023 15:32:35 GMT

Hi Scott,

Thank you for the info. The Tech went to the site and could not do anything as the whole area had no power due to a transformer that blew up last night. Hopefully, by tomorrow it will be sorted them on Monday I can start working again.

Thank you so much.

Re: APs Cannot join the Controller

Allan001 — Fri, 24 Mar 2023 15:33:39 GMT

Hi Balaji,

Thank you so much.

Re: APs Cannot join the Controller

Scott Fella — Fri, 24 Mar 2023 16:15:27 GMT

Okay... thanks for the update.

Re: APs Cannot join the Controller

Rich R — Fri, 24 Mar 2023 23:56:14 GMT

Just one more thing to check for: if the APs are loaded with a very old version of AireOS then they may not be able to join the 17.6.5 WLC (due to security related changes in CAPWAP protocol).

In which case you'll need to manually update the AP code before they'll be able to join.

Re: APs Cannot join the Controller

Allan001 — Mon, 27 Mar 2023 23:18:13 GMT

Hi all,

I apologise for taking too long to share the AP console output. The transformer was only fixed later last night. I got the AP output early but was busy with other stuff. At the bottom of the output, I can ping the controller .2 from AP .111. The AP has obtained a correct IP Add from the DHCP configured in the controller.

Thank you for your patience

Re: APs Cannot join the Controller

Rich R — Mon, 27 Mar 2023 23:35:52 GMT

Your AP is running as an EWC WLC and at least one other AP is running as EWC. You can convert it to capwap mode by a number of methods:

For EWC: https://www.cisco.com/c/en/us/support/docs/wireless/embedded-wireless-controller-on-catalyst-access-points/215303-embedded-wireless-controller-conversion.html#anc18

Accessing AP Console From EWC (former apciscoshell)

When console cable is plugged into the AP running EWC image, an EWC prompt will be shown by default. If, for any reason, access to the underlying AP shell is required, it can be done using:

EWC#wireless ewc-ap ap shell username admin

admin@192.168.129.1's password: Cisco123

To exit back to EWC shell, use:

AP1>logout

Connection to 192.168.129.1 closed.

EWC#

Note: This command is equivalent to apciscoshell that was previously available in Mobility Express controllers.

Converting EWC Back To Lightweight CAPWAP Mode

If AP running in EWC mode needs to be converted back to lightweight capwap mode, it can be done via:

AP1#ap-type capwap

AP is the Master AP, system will need a reboot when ap type is changed to CAPWAP

. Do you want to proceed? (y/N) y

Important: This command will perform a complete factory reset of both AP and EWC partition. Make sure to backup existing EWC configuration before conversion.

https://www.cisco.com/c/en/us/products/collateral/wireless/embedded-wireless-controller-catalyst-access-points/white-paper-c11-743398.html#Conversion

Converting EWCs to CAPWAP using option 43

DHCP option 43 is a vendor-specific option and is used for providing WLC IP addresses to the access point. Using option 43 with a specific subtype option, you can have the EWC convert to CAPWAP and join a WLC appliance or virtual controller. After the AP receives DHCP option 43 and subtype 0xF2 at bootup, the AP type will be converted to CAPWAP, and the AP will follow the regular joining process.

The DHCP configuration on the switch is shown below.

Switch(dhcp-config)#option 43 hex F2056464645801

Personally I recommend removing the IOS-XE EWC code from them completely because they have a nasty habit of unexpectedly re-activating EWC when they can't reach the WLC. Also note that running EWC and WLC together at the same time is NOT SUPPORTED. To completely remove the EWC re-flash them using the process at:
https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9120axi-access-point/217537-repairing-c9120-c9115-access-points-from.html

Re: APs Cannot join the Controller

Allan001 — Tue, 28 Mar 2023 06:41:21 GMT

Hi Rich,

Thank you so much for your prompt response and detailed info. I am better off removing the IOS-XE EWC code so we won't run into this problem again when the AP fails to reach the controller. I will read the links you shared before implementing them and let you know when I have the results. I will start the implementation tomorrow morning and see how it goes.

The first option is time-consuming since I have to go through this process on every AP. Option 43 might be quick, as I will only have to remotely configure the option on the switch.

Once again, thank you so much, and I appreciate your contributions.