topic Re: AP do not find Controller in Wireless

AP do not find Controller

vmhoang2 — Tue, 28 Nov 2023 10:59:01 GMT

I have issue, AP disconnect Controller C9800 and It rejoin controller. I remote SSH to AP and see that It send request to Controller, but Controller do not response ( WLC not found).

AP run PPoe, so I never power inline on switch and It reboot. After AP send discovery to Controller and Controller response.I have tried troubleshooting, but don't know what the cause is.

Has anyone encountered this problem? help me !!!

Re: AP do not find Controller

Mark Elsen — Tue, 28 Nov 2023 12:03:02 GMT

- (include AP model , controller model and software version being used on the C9800 too)
- Have a checkup of the C9800 current configuration with the CLI command show tech wireless ; feed the output into
Wireless Config Analyzer
- Check controller logs too when the AP tries to join
- Use these tools to further debug the AP join problem : https://logadvisor.cisco.com/logadvisor/wireless/9800/9800APJoin

Re: AP do not find Controller

MHM Cisco World — Tue, 28 Nov 2023 14:24:18 GMT

Show wireless state ap join summary

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Re: AP do not find Controller

vmhoang2 — Tue, 28 Nov 2023 16:18:03 GMT

Hi Marce 1000,

Wireless controller is behind a NAT device and Wireless Controller manages only Access Points reachable through the public internet (external APs). I configuration Controller in the CAPWAP discovery response to both the public IP and the private IP.

Could this cause a discovery error or could it have any impact?

Re: AP do not find Controller

vmhoang2 — Tue, 28 Nov 2023 16:18:42 GMT

Hi NMH,

Could this cause a discovery error or could it have any impact?

Re: AP do not find Controller

Mark Elsen — Tue, 28 Nov 2023 16:33:17 GMT

- APs must have an access path to the controller , make sure that is not blocked by firewalling (e.g.) ; simple test could be to try to ping the controller from an external AP.

Re: AP do not find Controller

vmhoang2 — Tue, 28 Nov 2023 16:40:19 GMT

AP can ping to Wireless controller and Firewall open port upd 5246 and 5247.

Re: AP do not find Controller

MHM Cisco World — Tue, 28 Nov 2023 16:47:45 GMT

Yes it can be NAT issue ,

do you use NAT 1:1 or port forwarding?

Re: AP do not find Controller

vmhoang2 — Tue, 28 Nov 2023 16:59:57 GMT

i used Nat 1:1.

I have enabled capwap debug application events. I have seen AP send discovery to controller both public and private ip. But the Controller is not responding. Then I turned off POE on the SWitch and turned it back on. The AP reboots, sends the discovery to the controller, and Controller responds.

Now the AP joins the Controller.
I still don't understand why this problem occurs.

Re: AP do not find Controller

MHM Cisco World — Tue, 28 Nov 2023 17:03:51 GMT

When it happened again check NAT translate in fw is it add or not.

Also how ap discover wlc IP via dhcp or dns?

Re: AP do not find Controller

vmhoang2 — Tue, 28 Nov 2023 17:08:00 GMT

Yes,

AP discovery WLC ip, I used command Capwap ap primary-base on each APs.

Re: AP do not find Controller

Mark Elsen — Tue, 28 Nov 2023 17:15:49 GMT

>...AP can ping to Wireless controller and Firewall open port upd 5246 and 5247.
As mentioned before look into : https://logadvisor.cisco.com/logadvisor/wireless/9800/9800APJoin

Re: AP do not find Controller

MHM Cisco World — Tue, 28 Nov 2023 17:18:40 GMT

Let make second look to issues

Why shut no shut porr make connection success?

Wlc is behind NAT and it use public IP but sure AP not use public IP

It use private and hence AP also behind NAT, this NAT is dynamic I think and it have absolute times when end the NAT is remove and this make wlc receive packet from new AP port source.

Make udp nat timeout of AP is long enough.

MHM

Re: AP do not find Controller

vmhoang2 — Tue, 28 Nov 2023 17:34:34 GMT

That's a great explanation.

I want to recreate that environment. Can you give me direction to solve that problem.

Re: AP do not find Controller

Rich R — Thu, 30 Nov 2023 00:13:12 GMT

If the AP joins after power cycle then you've hit a software bug which was preventing join.

Make sure your WLC software is up to date as per TAC recommended link below - currently 17.9.4 + SMUs + APSP6.