AIR-LAP1242AG and 6 connector third party antennas

[joanna.lenczewska]

We are troubleshooting connectivity issues in one of our warehouses. The RF guns being used are Motorola/Symbol MC9090. They do support 802.11b/g/a.

We moved almost all of them to 5GHz. While moving around and scanning guns drop from the wireless network. I did the site survey and the coverage looks good. There are a few things that we are looking in but there's one thing in particular that I'd like to find out. Cisco TAC support noticed that we are using Terrawave MIMO antennas. We bought those to support "n" in case we decide to swap the 1242s with newer models in the future. So the antennas come with 6 connectors - 3 for 2.4GHz and 3 for 5GHz. Obviously 1242AG supports only 2 of each. So 1 2.4GHz and 1 5GHz cables are not plugged in and just hang there. Cisco TAC said that since that is a MIMO antenna with 6 connectors that may be our problem.

I called Terrawave and was told that the antennas are passive devices and since the 3rd cable is not plugged in the AP won't try to use it.

Any thoughts?

Thank you,

-Joanna

[Stephen Rodriguez]

Well the 1242 is only going to transmit off of one 'side' at time.  So first question, what lead is connected to the port marked 'right' on the 1242?

With the MIMO AP, the center port is a RX only, so if you had the center connected to either left or right on the AP, potentially you could have issues.

While we're on this subject, do a search for the 9090 scanners with google.  you should find plenty of evidence that they have connectivity issues in general.  If it's only an issue with roaming, there maybe some tweaks that need to be made to the supplicant on the 9090.

To further assist with this, please let us know the software versons running on the controller as well as the config for the WLAN they are connecting to.

Cheers,
Steve

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[joanna.lenczewska]

The Terrawave antenna has 3 connectors for each band. The cabled are labeled only with "2.4" or "5". The 1242AG has only right/left plug for 2.4 and right/left for 5. So I plugged in only 2 cables on each side. I don't think there's any order to which cable goes to which connector on the AP.

We just upgraded our WLCs to 7.0.98.218 .

The WLAN that RF guns connect to is configured for both WPA and WPA2 and AES and TKIP and we are running H-REAP.

Thanks!

-Joanna

[Stephen Rodriguez]

for the antenna, that could be true, I'd still connecct the outer of the two for the band myself.

As for the WLAN, dumb it down a bit so there is not so much information in the beacon that the device has to process.  Make it either WPA2/AES or WPA/TKIP.  You may also want to try connecting a laptop to that WLAN and see if the issue persists.

If you are doing 802.1x, you may want to look at my document on eap timers as well.

[joanna.lenczewska]

Stephen,

The antenna comes with 6 cables hanging in the middle. They are only labeled with the band (2.4 or 5). Because of that I cannot really know which cable of the 3 goes to which connector on 1242. Terrawave doesn't talk about it too.

Very good EAP document you posted! I inherited both WLCs with the following EAP settings:

(CV-WLC-B) >show advanced eap

EAP-Identity-Request Timeout (seconds)........... 30
EAP-Identity-Request Max Retries................. 2
EAP Key-Index for Dynamic WEP.................... 0
EAP Max-Login Ignore Identity Response........... enable
EAP-Request Timeout (seconds).................... 30
EAP-Request Max Retries.......................... 2
EAPOL-Key Timeout (milliseconds)................. 5000
EAPOL-Key Max Retries............................ 4

Based what you wrote our RF hand held guns have to wait 30 sec to reauthenticate. Of course they roam constantly. I ran a report using WCS to track the clients and see how and when they are changing APs. And I noticed (before I read your document) that when tey disassociate they re-associate after 30 sec on average.

00:15:70:89:81:e4	05/05/2011 09:09:44 EDT	05/05/2011 09:10:00 EDT	BV-AP01	11a	Shawnee	16 sec		New association detected
00:15:70:89:81:e4	05/05/2011 09:08:48 EDT	05/05/2011 09:09:17 EDT	BV-AP01	11a	Shawnee	29 sec		Disassociation detected
00:15:70:89:81:e4	05/05/2011 09:06:23 EDT	05/05/2011 09:08:48 EDT	BV-AP03	11a	Shawnee	2 min 24 sec		New association detected

Could you help me out with those settings please?

I didn't see any problems while walking around with my laptop. As you mentioned laptops are a little more forgiving than hand held scanners.

Thanks a lot for your help!

-Joanna

[Stephen Rodriguez]

Those EAP settings should work. That 30 seconds is the time the WLC will wait before it sends another auth packet, I don't encourage that long of a time, cause if there is an issue, it takes forever to roam.

What I would think is happening, is the handheld is a bit aggressive, so when it doesn't get response, it drops off.  Changing the timers might help if that is the case.

To troubleshoot you'd need to be able to pull multiple wireless sniffers, channel the HH is on, and the channel it will roam to.  This way we can see the packets that are in the air between the AP and the HH.

Cheers,
Steve

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