Wireless Access

Hi,

 

Controller: W3200

AOS: 6.4.0.3

AP: AP105

 

I am in the process of trying to troublehsoot some complaints we have received pertaining to signal strength.

When I started to look into the issue I noticed that in the area where the complaints are coming from, the primary AP in the location is not getting any clients connected to it.

This is a new issue as we have never received complaints until recently.

 

I verified this by looking at the Controller under Dashboard > Access Points and monitoring the AP.

 

I took a laptop down to where the AP is. We do not have a dense deployment so I stood in a spot where I figured I would get bumped to this AP as it would have provided the best signal strength, but for some reason my wireless client wasn't moved. I know this probably isn't the right way of testing, but I am new with troubleshooting wireless issues such as this.

 

I have confirmed that the AP is apart of the Mesh and based on the data the controller is providing I can't see anything that stands out about this AP that could indicate there is a problem.

 

I did notice that there is one other AP that is in the same vacinity (probably within 15-20 meters) that all the clients seem to be connecting to.

 

What steps can I take to troubleshoot this issue?

 

Thank you,

 

Cheers

See if that AP is even broadcasting an SSID:

 

"show ap bss-table | include <name of ap>"

Thanks for the response @cjoseph!

 

From the read out of the command it looks like the AP is broadcasting an SSID.

I issued the same command for two other AP's that are close by. One thing that stands out to me is that of the 3 there is one that is doing the MAX EIRP while the other two are showing a value of 9. Does this mean anything significant?

 

 

Cheers

9 is the lowest, besides 6.   That power is normally set that low in dense deployments indoors.  If you have that power outdoors, that is a good reason why clients are not connecting.  The 802.11a radio is at regulatory maximum, but the g radio is very, very low, so it is not desirable to 2.4ghz clients.

 

If there is another access point in the area that is at maximum power, clients would rather stick to that access point.

 

Since this is outdoors, the placement and positioning of that access point is also important.  AP-105s are downtilt omnidirectional pattern and should be mounted on a ceiling indoors for the best performance. 

This is actually an indoor deployment. However, it is in a warehouse environment. The AP's are mounted to the rafters but are about 25 feet from the ground.

 

Unfortunately I do not have any staticial data to back up that these were working normally at one point. All I can really go on is that we have never had complaints in this particular area.

 

Is there any reason why there would be such a huge difference in the EIRP values between these 3 AP's?

These AP's are all fairly close together. I don't have exact measurements but between 15-20 meters and below.

 

We have never played around with how the radios operate either.

Well, at that height access points can see each other quite clearly in open space, so it might see 3 or 4 other access points on the same channel.

 

 show ap monitor ap-list ap-name <name of that ap>

 

 

You might have to raise the ARM min tx power for the 2.4ghz to something higher than 9

 

In a warehouse quite frankly you would  sometimes have to mount access points at every 100 feet because they have such clear line of sight of each other and their clients.

 

Use inssider to see how well you can see access points at ground level, to get an idea of how well the signal is propagating.

Yeah it looks like you are right about the visibility.

 

It looks like the AP's are adjusting the strength on the fly but the one AP is staying at a persistent 22. Would it make sense to possible lower the max output for the AP that is constantly at 22?

 

 

One the challenges we have with our warehouse is that we have high metal racking that interfers with signal so we have had to add additional AP's to compensate.

 

I will go down again and take a reading with inssider to get idea of propagation. 

 

Thank you,

 

Cheers

You can change the ARM-MAX-TX power to 18 so that it does not go that high.  (22 is too high in a warehouse by the way).

 

If you have racking that goes all the way up to the ceiling, hopefully you mounted in the aisles to mitigate that.

 

You might not have to change much.  Once the power on the access points are a little more even you might have more even coverage/performance.  Ultimately, how the users see the access points might be the biggest determining factor of what you would attempt to change (inssider or a site survey mode on the warehouse devices).

 

Helpful ideas about warehouse deployment can be found in Chuck L's presentation here:  http://community.arubanetworks.com/aruba/attachments/aruba/tkb@tkb/92/1/Airheads%20Barcelona%202010%20-%20RF%20Design%20for%20Retail%20Warehousing%20Manufacturing.pdf

I will investigate lowering the ARM-MAX-TX power value. Thank you for the suggestion.

 

The racking almost reaches the top, but can fluctuate. We did, thankfully, mount in the aisles. We are in the midst of adding additional APs though because we do have some weak areas. But possibly modifying the existing AP's a little might help a lot.

 

Thank you for the link.

 

I will investigate the issue and see if I can't get it sorted out!

Just to make sure I am looking in the right place.

Do I adjust the ARM-MAX-TX through the Adaptive Radio Management (ARM) Profile?

I figured I would start with adjusting it just under the single AP that has the really high value and see how that changes the signal distribution. Still need to plan it all out though.

 

 

# rf arm-profile "<profile name>"
  max-tx-power "18"

 

Correct. It could take some time to change the signal distribution if you change the power on a single access point.

Thank you again!

 

Do you think adjusting it on a single AP first to observe the behavior is wise?

Or does it make more sense to adjust it for the AP Group?

That would depend on what the problem is in the first place.  If your problem is with a single AP, you should do something to deal with that AP, rather than affecting everything else....regardless of whether or not you think you can improve everything.  If the problem is with everything, you probably need time to gather enough information to support whatever possible move you want to make, first.

 

You should only do what is related to why you are there in the first place, otherwise you could trigger other unforseen issues.

 

That is what I would do.

 

 

 

That makes complete sense.

 

Thank you for your advise.

Just wanted to update.

 

I did some testing with the AP I suspected was causing the problem.

I played around with adjusting the MIN/MAX EIRP value for the suspected problem AP as well the surrounding AP's.

 

Regardless of what I did, I could not get any clients to connect to the AP.

 

Luckily I had a spare AP. I hooked it up temporarily to see what would happen. As soon as it came up my test laptop connected to this temp AP. I modified the MIN/MAX EIRP value in the profile for this AP and I was still having clients connecting to it.

I eventually swapped out the AP I suspected to have an issue with the spare AP we had.

 

I have now done some testing with the problem AP. I used the controller command cjoseph provided and inSSIDer and from what I can tell, the problem AP isn't actually broadcasing the SSID's. I am looking for the radio MAC's (or what I think are the radio MAC's) in inSSIDer and none of them are showing. I am not sure if this is a definitive way to identify whether or not the AP is broadcasting, but when I compare the results to an AP that seems to be working correctly, I can account for almost all the radio MAC's through inSSIDer.

 

Cheers