topic Re: AP not joining WLC - incompatible? in Wireless

AP not joining WLC - incompatible?

joebrug — Mon, 05 Jul 2021 16:01:51 GMT

Hi.. we currently have 5 AP's running for months now, boss wanted to add a 6th. I configured everything and plugged it in, but it never joined the WLC. After spotting a discrepancy in DHCP, I'm now wondering if this is a different model that isnt compatible with our setup.

DHCP is showing the working 5 as:

AP188B-4508 (WLC says AIR-AP1852I-B-K9 for model)

The non-working one is:

AP70F3-5A50 (Cant see it in WLC, dont know model of it, Id have to drag a ladder up there)

WLC is 2504:

Software Version	8.3.140.0
Field Recovery Image Version

Re: AP not joining WLC - incompatible?

joebrug — Fri, 24 Aug 2018 19:47:26 GMT

Nevermind, I figured this out.
Because the WLC and the AP are on different subnets, the AP was not discovering the WLC. When I changed the APs vlan to that of the WLC, it discovered it/downloaded firmware successfully. Now I can move it back to AP vlan. I guess this is called 'Priming" from what I read. Now I will look into either DHCP option 43 or using DNS so the AP's can find the WLC.

Re: AP not joining WLC - incompatible?

Rasika Nayanajith — Fri, 24 Aug 2018 19:53:19 GMT

That's right.

Once you put AP into same vlan as WLC management, then simple L3 broadcast from AP will reach to WLC & they will discover each other.

If you want to setup AP on other vlans (other than WLC mgt), then DHCP option 43 or DNS method is more practical.

Below post may also help you to understand different methods available

https://mrncciew.com/2013/03/17/ap-registration/

https://mrncciew.com/2013/05/04/wlc-discovery-via-broadcast/

https://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/97066-dhcp-option-43-00.html

HTH

Rasika

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Re: AP not joining WLC - incompatible?

joebrug — Fri, 24 Aug 2018 19:57:45 GMT

Thank you for that. Is there a preference on DHCP option 43 or DNS? I'm reading the link you posted.. a little confused as to if i need both Option 60 and 43 or just 43. and I assume that I simply put it on the DHCP Scope that handles the AP's, correct?
Finally. to test this.. is a "Clear All Config" on the AP sufficient or will it remember the WLC IP?

Re: AP not joining WLC - incompatible?

Rasika Nayanajith — Fri, 24 Aug 2018 20:03:48 GMT

No, you do not need both option 60 & option 43.

Simply configure option 43 with WLC IP to be advertised via dhcp.

Yes, "clear all config" should work, please verify it having console session to your AP directly

HTH

Rasika

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Re: AP not joining WLC - incompatible?

Leo Laohoo — Sat, 25 Aug 2018 00:20:36 GMT

I'd prefer using DHCP Option 43.

Re: AP not joining WLC - incompatible?

KYLE MCLERREN — Sat, 25 Aug 2018 14:51:08 GMT

We use option 43 with static assignments. I'd recommend you not leave your AP's on normal dynamic IP assignment. The reason for this is: if your AP's are ever in a scenario where they cant reach the controller, they will fall back to DHCP and will re-request addresses from your DHCP server, making bad entries and filling up your DHCP scope.