1242AG AP's going up and down

Unanswered Question
Sep 14th, 2008

AP 'HMS-D123', interface '802.11a' is up on Controller ''.

AP 'HMS-D123', interface '802.11a' is down on Controller ''.

These events happen about every minute.

Model AIR-LAP1242AG-A-K9

IOS Version 12.4(10b)JA

AP Type AP 1240

AP Certificate Type Manufacture Installed

H-REAP Mode supported Yes

I get this from controller events

Mon Sep 15 02:47:23 2008: spamEncodeDomainSecretPayload:Send domain secret My_

Wireless<c6,55,6a,45,cb,28,86,af,bb,81,84,64,85,e7,04,6b,76,0f,a7,94> to AP 00:1f:9d:21:77:60

But I never get a successful corresponding event.

From the router when I do an debug ip udp I get these kinds of packets constantly. The ip in question for this ap is I do not see this behaviour from other routers or ap's- only from this campus that happens to have 1242AG's (prior we used autonomous ap's that have been upgraded to lwapp)

4w6d: UDP: rcvd src=, dst=, length=131

4w6d: UDP: rcvd src=, dst=, length=123

4w6d: UDP: rcvd src=, dst=, length=97

4w6d: UDP: rcvd src=, dst=, length=97

4w6d: UDP: rcvd src=, dst=, length=99

4w6d: UDP: rcvd src=, dst=, length=95

4w6d: UDP: rcvd src=, dst=, length=95

4w6d: UDP: rcvd src=, dst=, length=59

4w6d: UDP: rcvd src=, dst=, length=146

4w6d: UDP: rcvd src=, dst=, length=180

4w6d: UDP: rcvd src=, dst=, length=180

4w6d: UDP: rcvd src=, dst=, length=180l

I get continuous udp's from every AP at this campus. All the ap's are on their own vlan. Their helper address is correct.

My biggest issue is that they are going up and down - a smaller issue is that I don't want them registering to the controller they are registering too - and my changes for primary, secondary, and tertiary don't seem to matter.

We use dns entry for discovery. I read in another post about OTAP but I don't know anything about how that is configured. I tried to use option 43 on this scope but that didn't work either.

How do I figure out exactly why they are going down? We use WCS as well.

I'm really at a loss to figure out what these ap's are doing. I have over 400 ap's and only the 1242ag's behave this way.


I have this problem too.
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bbxie Mon, 09/15/2008 - 02:38

If you can paste WLC's run-config, it could be easier to troubleshoot.

When 11a is flaping, how about 11b/g? Typically if 11b/g ok, but 11a is keeping up and down, there have a regulatory mismatch between AP and WLC. So check AP's country code(all ap-->details-->advanced) to compare with what you configured for WLC(Wireless-->country).

You can also use "debug mac addr xx.xx.xx.xx.xx.xx" and "debug lwapp events enable" in the WLC to do troubleshooting.

If it is possible for you to connect to AP's console port, then you can find out if there's any warning/error appeared in AP's console

As of your second question, pls. remember that AP will go through following discovery steps to try to find out all candidate WLC:

1. broadcast on local subnet(different vlan can use ip helper-address xxxx, ip forward-protocol udp 12223 and

ip forward-protocol udp 12222 to forward the broadcast)


3. Locally stored WLC IP address

4. DHCP option 43

5. DNS resolution of “CISCO-LWAPP-CONTROLLER.localdomain”

After discovery, AP will generate a list of all candidate WLC, then AP will select a WLC to join according to following criteria:

p1.If AP has been previously configured with a primary, secondary, and/or tertiary controller, the AP will attempt to join these first (specified in the Controller sysName)

p2. Attempt to join a WLAN Controller configured as a “Master” controller

p3. Attempt to join the WLAN Controller with the greatest excess AP capacity

So if you want to use configuration of primary,secondary WLC, you should:

1. Use WLC's sysname instead of IP address to represent WLC

2. The manually configured primary/secondary WLC can be found in the discovery phase(using one of above mentioned 5 method)

Scott Fella Mon, 09/15/2008 - 19:57

So this is only happening on one site? What WLC do you have and how is everything setup in your environment? Bo posted good points on how the join proccess works. Is this a new install or did everything happen to fail after a while?

jbirk Tue, 09/16/2008 - 19:33

My issue is resolved... Seems that we had a security policy utilizing AAA on the WLC but not on the controllers (or vice/versa). Anyway we should of been using the machine generated certificate but the ap was trying to use AAA.


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