Wireless Access

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Occasional Contributor I
Posts: 5
Registered: ‎07-25-2013

Too Many AP's?

Hello everyone-

 

I inherited an Aruba Instant network with roughly 10 AP's covering 6250 square feet of open floor plan space.  Downstairs is 4764 sq/ft, and the upstairs loft is 1486 sq/ft.  Upstairs I have 4 AP's around the perimeter.  Downstairs I have 6 AP's in variety of positions (perimeter, with a couple interspersed inside the perimeter). 

 

I have been battling dropping network issues, and have manually shut down a couple of IP's either administratively, or via pulling the cable.  A couple of the units were showing up as rogues, and one was not getting any throughput to the users closest to it. 

 

I have 3 SSID's, one is a guest, and two belong to the corp.  I had created a 2nd ssid to try to get away from the interference of the rogue AP's, as well as from a couple of airport extremes that had the same SSID.  I managed to remove those from the environment when I found them.

 

I need clarification on the maximum threshold per AP.  I have one AP that is getting 53 clients, while the others are in the teens.  I want to make sure that if I set both SSID's to a maximum threshold of 10 each, then with the 2 SSID's, and the 2 Radio's per AP, the max allowed per AP would be 40?  After which the clients will search for the next closest AP?

 

There was a general meeting the other day that had 60+ clients on one AP, and their wireless dropped to a crawl.  Any help would be greatly appreciated.  It's a mixed environment of 105's and 135's.

 

Thanks-

Chris

MVP
Posts: 4,238
Registered: ‎07-20-2011

Re: Too Many AP's?

[ Edited ]

 

Not sure if you did a wireless survey before deploying your APs but it is possible that the APs are hearing each other too much but you can verify this by doing the following :

 

The AP ARM history will tell you if APs are changing channels and power levels too much and why (because interference , just a power change , etc..)

Screen Shot 2013-07-26 at 5.48.32 PM.png

 

IF this is the case you can play around with the power levels to make sure the minimum is not set to high

Note : Make sure you test this since decrease the power too much may lower your signal coverage

Please read this doc:

http://www.arubanetworks.com/wp-content/uploads/Indoor80211n_2012-05-31.pdf

Screen Shot 2013-07-26 at 5.49.16 PM.png

 

You can work around the amount of devices per radio you can use spectrum load balancing

 

Screen Shot 2013-07-26 at 5.49.01 PM.png

 

You can also change the amount of users per SSID , you should also enable broadcast filtering to decrease the amount broadcast in the AIR

 

Screen Shot 2013-07-26 at 6.05.13 PM.png

 

Having a mixed environment of 105s and 135s is not a huge deal (of course is not the best scenario) but be aware that 135s have a 3x3:3 vs 2x2:2 on the 105 so the performance will be much better on the 135 .

 

In locations that you are expecting too many devices then you will need more APs to cover those areas , please read this doc:

http://www.arubanetworks.com/wp-content/uploads/DG_HighDensity_VRD.pdf

 

 

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
Occasional Contributor I
Posts: 5
Registered: ‎07-25-2013

Re: Too Many AP's?

Thanks Victor-  I will take a look at all that you sent me.  For my information, how many times of switching channels is too much?  Every 15 minutes?  I don't think my predecessor did a wireless survey, as I have AP's all over the place in no particular pattern.  I have a corner room with an AP inside the room, and then another AP right outside the door to the same room, not more than 5 feet away.  Not to mention an additional AP in the room directly above this one, about 10 feet horizontally away from these other two.  It's quite a scene..

 

I'm dropping the amount of allowed users to about 10 per radio per AP per SSID.  So roughly 40 per AP.  I don't know if I can do broadcast filtering, as this is an all Mac environment, and they stream to AppleTV's using Airplay.  From what it sounds like, the filtering will break Airplay?  I will definitely look into reducing the power on some of these AP's to stop them from interfering with each other.  I've put a couple in monitoring mode to help with this.

 

When I'm looking at the interference graphs, I see when the interference line goes higher than the valid (blue) line.  I'm assuming this is bad?  Most of my AP's are showing this sort of line where the interference is greater than the valid line.  The AP's I put into monitoring mode show this line greatly exceeding the valid line, but I assume it's because the AP's are no longer accepting clients..

 

Thanks for you help--  It looks like the previous guy was battling this for a year before I picked it up.  There is a huge reliance on wireless at the company.  I've been moving clients off the wireless and onto the wired (printers, appletv's, etc..) to try and reduce the overall usage and reliance on wifi...

 

-Chris

MVP
Posts: 4,238
Registered: ‎07-20-2011

Re: Too Many AP's?

[ Edited ]
- channels changing every 15 min is an indication that 802.11 or non-802.11 are too close to your APs and ARM has to recalculate the channels/power allocation because the interference index coverage is too high

- having APs that close too each other is not good (5 / 10 feet away) the minimum distance shouldn't be less than 30 feet away for optimal performance 802.11g radios in a typical office where theres no major walls that may be absorbing your wireless signal , even APs in adjacent channels can potentially degrade the signal . In some cases you could have APs closer than 30 fit away like if you need APs in a conference room, lecture room where you are expecting more than 35 - 40 users with laptops

- one thing you could do is make some of those APs air monitors to help calculate the best channels / power assignment for each IAP

Hope this helps
Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
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