Controllerless Networks

Occasional Contributor II

Newbie. DENSE interference enviroment.

I had some IAP-205's laying around left over from some upgraded client projects and decided to set them up at home. I live in a large apt complex, with large apartment complexes around mine.


IDS is showing aprox 400 forgien access points and aprox 100 forgien clients. Its a huge mess of 2.4/5 B/G/N/AC 20/40/80 mhz junk. 42 access points are at significant signal levels in the 2.4Ghz band.


Im using 3 IAP-205's running Its a one bedroom apartment, 720 sq ft.  I prefer 5Ghz and most devices end up there, but, I have one 2.4Ghz only device so I must have 2.4Ghz enabled.


Leaving ARM on auto and turning off client aware to watch what ARM does I see the 2.4 Ghz channels flap around on channels and they never settle down, for obvious reasons.


I added all channels between 1-11 to the ARM list and it settles more on odd channels like 2 9 11..  There are forgien access points on all sorts of odd channels.


So I am inclined to turn off ARM auto, manually pick the channels with the least issues and set power at max.


So I have a few questions as I have never encountered such a dense interference enviroment before. Is the approach of fixed channels, max power and lots of 205's for least distance the right way to go ?


I have increased the immunity level to 4 on the 2.4Ghz band. Spectrum analysis also shows a whole zoo of issues there too.


I have decided to run a "monitor" and I have set it to very agressive settings. This has already identified all sorts of evil stuff and bad guys.


The 5Ghz band is fairly ok. Lots of room to spread out up there.


I will run with Client Aware on of course, I am just running with it off to allow  ARM to make chaoices and I look at the ARM logs to see what it has been doing and what channels/power it likes best.

Occasional Contributor II

Re: Newbie. DENSE interference enviroment.

ARM history of the three access points..  So they all jump around endlessly.



Occasional Contributor II

Re: Newbie. DENSE interference enviroment.

So ARM is not working correctly in this high interference enviroment. It rotates thru all channels on all access points on the 2.4Ghz band. So I need to change settings to make it stable. I would like to preserve its ability to switch in a severe situation, so, if I "admin assign" power and channel I loose this ability.


So is there a deep setting i can do to make it less sensitive ? IE to be tollerant of fairly high levels of interference ?


I think I have to just "admin assign" channel and power and that is my only choice ?

Guru Elite

Re: Newbie. DENSE interference enviroment.

Unfortunately, there are alot of non-wifi interferers out there in the 2.4ghz spectrum like Microwaves, wireless video cameras and those might be causing the lion's share of the crippling interference.   There is really very few places to go for relief in the 2.4ghz band.   You might be able to see many other access points in the 2.4ghz band because the AP-215 has good receive sensitivity, but unless they are very close to you and they are generating alot of traffic much of the time, they are typically harmless.  You should only use channels 1, 6 and 11 for your own wlan, because they do not overlap and cause interference to other channels like the odd 2,3,4,5,7,8,9,10 do.  You will still "interfere" with the access points on the odd channels on the foreign access points that you see, but there is a wall between you and those access points so the practical effect will be less.  You can uncheck ARM scanning so that access points will not change channels.


If you are only supporting a single device, you can certainly fix the channels to 1, 6 and 11 and leave it alone.  The ship as sailed in the 2.4ghz band for many customers and high performance networks rely on the 5ghz band, and only purchase devices for that.


Back when there were not so many devices in the 2.4ghz band, ARM could conceivably adjust between the 1/6/11 channels, but in this day 2.4 should only be reserved for devices that are forced to use it.  Stick to 1/6/11 in your own environment so that you do not cause cochannel inteference locally. 


*Answers and views expressed by me on this forum are my own and not necessarily the position of Aruba Networks or Hewlett Packard Enterprise.*
ArubaOS 8.4 User Guide
InstantOS 8.3 User Guide
Airheads Knowledgebase
Airheads Learning Videos
Aruba Central Documentation
Sign up for Security Alerts
Aruba Technical Webinars
Occasional Contributor II

Re: Newbie. DENSE interference enviroment.

Thank you. That was about what i figured.


Cochannel interference *might* be better then forgien access points. I have some access points that are screaming high power and trying to do wide channels on 2.4 that are literally on the other side of the wall from me. 2 of them. Directly around me 1,6,11 are all taken twice over. There is other weird stuff I can see with spectrum analysis too. The 2.4 band is getting almost unusable in dense multi unit dwellings. TV's / Roku's / Printers / Cable Boxes all spit out misguided wifi stations that also pollute. My **bleep** Roku Ultra uses Wifi to communicate with the remote !?!, I disabled that and went IR. And OF COURSE all those devices have terrible security and fixed passwords you can't alter.


The 2.4 Ghz band has truly gotten unusable in dense multi unit dwellings ( apartments ) these days. It sure would be cool if Aruba worked on some protocols to adapt better to these messes. Like doing statistics on all the interference over days/months to determin the best approach which included cahnnel / power / noise immunity and a host of other settings. Maybe a mode you could place the cluster in that would analyze things to determine the best settings for everything. CPU power has reached a point that this is possible.


Well.. Im gonna just go lock down my channels , turn off ARM and look at actual device performance and try every channel and see which ones work best for the devices in real use per station. I am going to try odd channels just to see what happens. Right now I am trying 3,9,11 and, crazy as it sounds, that is producing good results. Im going to have to run multiping doing like 2 pings a second and chart that for days and see how those charts look. I will then need to try other channels and do it all again.


THEN once I have figured out the perfect channels/power some idiot will come along with some new devices next door and blast some new channels at me.


5Ghz is of course weak enough at distance with lots of room that things are good in 5Ghz land.


Dropping these into my apartment has been educational. Its way more difficult then doing a building or million dollar residental home.

Search Airheads
Showing results for 
Search instead for 
Did you mean: