WLANs appears sporadically on FlexConnect APs

ci-itsupport · ‎02-26-2016

I'm having a really odd problem with some 1142n APs running in FlexConnect mode. I am currently recreating the wireless infrastructure of my company, and part of this has included creating multiple WLANs to be used in all of our sites - two main SSIDs for company equipment (one at 5GHz and one at 2.4GHz, using 802.1x), a personal-use SSID (at 2.4GHz, secured with a PSK, access to internet and a very few company resources such as email), and a guest SSID (open authentication at 2.4GHz, with access only to the internet).

This is all driven by a 2504 WLC in our main facility. In our main site we have numerous 1702i APs in the office, each supporting every SSID, along with a few 1242ag APs that support all but the 5GHz SSID. We have another facility next door with a couple of older 1142n APs which also support all of the SSIDs. These are all in local mode, and they all work fine.

The problem is our remote office, where I am attempting to install two additional 1142n APs in FlexConnect mode. They are using local switching but are still using the WLC for authentication. I have the AP group and FlexConnect group configured for both, and have all WLANs assigned to them. However, for some reason these APs will pick and choose what SSIDs they broadcast and in fact what WLANs they will actually support seemingly at random. When they do present an SSID to join, I am able to join it without issue, but it will occasionally just "shut down" and I can no longer connect.

Rebooting the APs seems to shuffle what WLANs they support. They both seem to favor the 5GHz WLAN, but the other WLANs locked to 2.4GHz come and go. Sometimes the 5GHz WLAN disappears too. To make it stranger, they won't necessarily have the same WLANs present at the same time! Sometimes shortly after booting they will have all of their WLANs, but then several WLANs will disappear.

I'm verifying all of this information with InSSIDer, where I can see what SSIDs are being broadcast, along with the MAC of the AP and some history on the signal. The WLC is running software version 8.0.121.0, which is the last version that supports the 1242ag APs.

Does anyone have any ideas on what might cause the FlexConnect APs to arbitrarily drop certain WLANs? I'm hoping that I am just missing something simple...

Thanks in advance!

Philip D'Ath · ‎02-28-2016

Yucky. Is the bandwidth between the AP at the remote site and the WLC being squeezed at all?

Anything appearing in WLC log that is interesting?

ci-itsupport · ‎02-29-2016

Nothing really stands out in the logs (mostly just NTP errors where it appears to be trying to contact an NTP server with address ::, and a few EAP invalid replay counter errors). I can't imagine an NTP error, or a problem with a client authenticating, would result in missing/spotty SSIDs...

I did consider the bandwidth squeeze since our remote office is only connected by a 6Mbps line. However, I was able to replicate the setup on the same physical network as the WLC and I still have the issue.

Part of me thinks it's just an issue with that software version. However, I don't like the idea of rolling it back and I can't upgrade any further unless I replace the 1242ag APs.

Philip D'Ath · ‎02-29-2016

Yucky. It sounds like a software issue.

If the number of 1242's are low, I think I would work on getting them replaced, and then move onto a new software version.

ci-itsupport · ‎03-02-2016

A few observations:

Running "show capwap reap association" on affected APs shows that they do have all SSIDs listed. Oddly, some of the SSIDs that are not broadcasted show as having clients! My guess here is that because they are in an environment with fully functional "local" APs they are picking up some roaming clients.

I tried to replicate the problem with a different AP, an older 1131g that I had. I put all SSIDs except the 5GHz one on there, and voila, all showed up. As a test, I removed the 5GHz WLAN from the group and found that the 1142n's will show all the 2.4GHZ WLANs just fine! Replacing the 5GHz WLAN causes several of the 2.4GHZ WLANs to drop from the 1142n's.

So it seems the problem revolves around the presence of 5GHz WLANs on the access points. I'm going to try to pull one of the 1702i's out of production and put it into the group as well to see if the same thing happens.

Unfortunately, at this time replacing the 1242ag APs is not an option, so I can't really go forward with an upgrade. I may just drop the 5GHz WLAN at the remote site and go from there. The 2.4GHz band is very congested up there, but at least it will work!

ci-itsupport · ‎03-03-2016

Another update - the problem does not appear if I use one the 1702i's in FlexConnect mode. They are able to support all 2.4GHz WLANs and the 5GHz WLAN at once. Tells me that the problem is at least partly on the 1142n's.

Are there any hardware limitations on the 1142n APs that keep them from being able to use WLANs in both 2.4GHz and 5GHz when in a locally-switched FlexConnect mode?