Lightwieght Access Points Randomly Move To Different Controllers

Unanswered Question
May 5th, 2009

In our environment we have 4 4400 series wlc's. The first two (#001 and #002) run our standard shop floor profiles with 5 different vlans, and these access points are only deployed in our shop floor environments. These access points are all 1242 ap's. We have one (#003) that runs a guest network for our customers. This set up is mostly 1500 series outdoor access points and a couple of 1242 ap's. We have the mac filter list set up for this WLC. Our last controller (#004) runs what we call our office standard ssid and has only 1130 series access points associated to it. The problem that I am having is that 2 (the same 2 every time) of our 1130's move from controller #004 to controller #001 around once a week. Every time this happens I delete all of the secondary and tertiary controllers from their list, reboot them watch them associate with controller #004 and again verify that #004 is the only one listed in the controller section and is listed as the primary controller. Is there something that I am missing or a bug about this?

Controller Info:

#001 - SW Version 5.0.148.0

#002 - SW Version 5.0.148.0

#003 - SW Version 4.2.61.0

#004 - SW Version 5.0.148.0

I have this problem too.
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gamccall Tue, 05/05/2009 - 07:34

I've always found that it's a much better idea to have all controllers configured identically, and then use AP Groups/ WLAN Override to specify which APs will offer which SSIDs. That way, you can sustain a failure of any of your controllers without losing functionality.

With that said: is controller #4 in the same mobility group with #1 and #2? If it is, you could think about making it a separate group.

ctoddrichardson Tue, 05/05/2009 - 07:57

I would first look to see why the APs are disassociating. Are they POE, and perhaps a switch is losing power momentarily? The APs are supposed to send heartbeats to the WLC every 30 seconds, and if not reachable will release/renew IP and search for the WLCs. In theory I know the APs are supposed to come back up to Primary, Secondary, Tertiary - sequentially. However we are having a similar issue where we have configured Primary and Secondary controllers for the APs, and they have come back up associated to a different controller (not a specifically specified controller, but in the same Mobility Group). I think this is done via the Dynamic Discovery algorithm which seeks out the least congested controller. But not sure why it would do this when we have specified a reachable Primary and Secondary. Maybe it is fixed in the new code, we are running 4.1. Sorry - not an answer for you - but you are not the only one this is happening to.

kfarrington Sat, 08/29/2009 - 03:47

Yeah. We have 4 WLCs in a mobility group. All identical s/w etc etc.

We set primary and secondary controller names, but they move onto the other two controllers which are not specified under the AP for primary or secondary, but are part of the mobility group.

Why is this?

Thx

Ken

Leo Laohoo Tue, 05/05/2009 - 14:15

Firstly, I agree with Gabriel McCall. It would be wise for all the WLC/WiSM to run the same firmware and bootstrap.

Secondly, if you are trying to have some AP's broadcast specific SSID's, you don't need to setup a different WLC to do so. All you need to do is to configure AP Groups.

Thirdly, you can configure up to three controllers for the LWAP to associate. Go to Summary > Under Access Point Summary > Go to All APs > Details.

Choose the AP you want, go to High Availability Tab and enter your controller details in the order of failover.

Controller #004 will not have this option. So you need to enter the details above via CLI using the command "config ap primary ?".

Hope this helps.

Lucien Avramov Sat, 08/29/2009 - 08:57

To add on this, if you have a WCS, the templates make it much easier to configure your Access-Points with the controller order and the wlan override.

l.mourits Mon, 09/14/2009 - 05:08

If your WLCs are in one mobility-group, and an AP keeps associating with another WLC then the one that is primarily or secondarily configured, that could indicate packet loss between your AP and your WLC (#004).

There is no other reason for an AP to home to another controller apart from loosing connectivity to the WLC that it has registered to. If rehomed, it does not home back to the WLC, only after reboot.

If your WLC #004 is on aother subnet and/or location, in a way there is no roaming required, you may consider putting that WLC in a separate mobility group.

I used to have one mobility group and wandering APs, when I had WLCs in different locations throughout the globe, and after I moved to separate mobility-groups (one per location) and setting DHCP for finding the seeding controller, my APs stopped wandering ;-)

Hope this helps,

Leo

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