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Regular Contributor I
Posts: 186
Registered: ‎03-22-2013

Troubleshooting a wifi problem

[ Edited ]

Would like some opinions on this capture I have done with Chanalyzer Pro.  3 AP93's have been deployed in a modular portakabin building, and wifi is very poor.  Due to internal layout, there are 2 APs on the ground floor, and 1 on the top.  The large open plan office upstairs, with one AP. has virtually no coverage with 80%+ packet loss (Ekahau Site Survey).

 

The 3 APs for some reason, are all on ch1.  ARM is enabled, and Im sure they can see each other, as Im able to view the other APs bssid's from each AP.  Ive noticed theres something around ch8, but have ruled this out.

 

I am very curious as to what all of the blue noise is across the spectrum.  We discovered the other day that the external shell of the structure is metallic  -  we had assumed it was simply some form of non metallic structure!   I can only perhaps guess that the noise we can see are reflections of the radio waves bouncing around internally?  

 

Would welcome any opinions, suggestion on how to improve wifi in this area.

 

mod1img.jpg

 

 

 

 

Guru Elite
Posts: 20,821
Registered: ‎03-29-2007

Re: Troubleshooting a wifi problem

Access points when new end up on channel  1 initially.  Do you have Client-Aware enabled in your ARM profile?  Try disabling that so that client associations will not keep access points from changing channel and power.

 



Colin Joseph
Aruba Customer Engineering

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Regular Contributor I
Posts: 186
Registered: ‎03-22-2013

Re: Troubleshooting a wifi problem

Still stuck on 1... :smileyfrustrated:

 

Does the image not suffest there aer othe rpossible issues, possibly environmental?

 

Cheers

 

 

Guru Elite
Posts: 20,821
Registered: ‎03-29-2007

Re: Troubleshooting a wifi problem


$k3l3t0r wrote:

Would like some opinions on this capture I have done with Chanalyzer Pro.  3 AP93's have been deployed in a modular portakabin building, and wifi is very poor.  Due to internal layout, there are 2 APs on the ground floor, and 1 on the top.  The large open plan office upstairs, with one AP. has virtually no coverage with 80%+ packet loss (Ekahau Site Survey).

 

The 3 APs for some reason, are all on ch1.  ARM is enabled, and Im sure they can see each other, as Im able to view the other APs bssid's from each AP.  Ive noticed theres something around ch8, but have ruled this out.

 

I am very curious as to what all of the blue noise is across the spectrum.  We discovered the other day that the external shell of the structure is metallic  -  we had assumed it was simply some form of non metallic structure!   I can only perhaps guess that the noise we can see are reflections of the radio waves bouncing around internally?  

 

Would welcome any opinions, suggestion on how to improve wifi in this area.

 

mod1img.jpg

 

 

 

 


It looks like there is something between channels 8 and 9, but I don't use that software, so I cannot interpret what it is....

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Regular Contributor I
Posts: 186
Registered: ‎03-22-2013

Re: Troubleshooting a wifi problem

As nothing is using channgel 8 or 9, Im really not conncerned...  I was more curious as to the blue noise that apparant right across the spectrum.

 

 

Guru Elite
Posts: 20,821
Registered: ‎03-29-2007

Re: Troubleshooting a wifi problem

[ Edited ]

$k3l3t0r wrote:

As nothing is using channgel 8 or 9, Im really not conncerned...  I was more curious as to the blue noise that apparant right across the spectrum.

 

 


Nothing is using those channels, but whatever energy is there could be keeping those access points from changing to channels 11 and 6.  I would grab the output of "show ap arm rf-summary <ap name>" to see what each access point thinks of those channels.

 



Colin Joseph
Aruba Customer Engineering

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Super Contributor II
Posts: 429
Registered: ‎01-19-2011

Re: Troubleshooting a wifi problem

This could be just a high background noise floor - is there any heavy duty electrical equipment nearby. The other possibility is Frequency hopping wireless devices i.e cordless phones and older wifi device that transmit randomly across the whole 2.4GHz band. Bluetooth devices operate in the same way but are low power and would not likely to cause that much interference.

Occasional Contributor I
Posts: 9
Registered: ‎12-17-2010

Re: Troubleshooting a wifi problem

It is still on Channel 1 beacuse the interference index is lower (total of 27)on it than 6 (133)and 11(136).  Your other APs are also seeing interference on those channels.

 

Since all APs are seeing noise that likely eliminates the Ekahau adapter's capture being the issue (bad connection etc) for the noise floor.

 

Your spike between 8-9 (which is in the 6/11 overlap)is possibily an AV transmitter and is intermittent given what I can see in the time period of the waterfall view. If utilization/duty cycle is high than it is very likely the explanantion for your ARM channel selection question. I would track it down and see if your background noise across 2.4 disappears.

 

Good luck

Guru Elite
Posts: 20,821
Registered: ‎03-29-2007

Re: Troubleshooting a wifi problem


Eastcoast wrote:

It is still on Channel 1 beacuse the interference index is lower (total of 27)on it than 6 (133)and 11(136).  Your other APs are also seeing interference on those channels.

 

Since all APs are seeing noise that likely eliminates the Ekahau adapter's capture being the issue (bad connection etc) for the noise floor.

 

Your spike between 8-9 (which is in the 6/11 overlap)is possibily an AV transmitter and is intermittent given what I can see in the time period of the waterfall view. If utilization/duty cycle is high than it is very likely the explanantion for your ARM channel selection question. I would track it down and see if your background noise across 2.4 disappears.

 

Good luck


Eastcoast,

 

Thanks for the analysis.

 

That RF summary output was just a sample of an access point in the office, not actual output.  I deleted it so that it does not cause any  further confusion.

 



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I
Posts: 9
Registered: ‎12-17-2010

Re: Troubleshooting a wifi problem

Sorry didn't notice the show ap arm rf-summary wasn't from the problem APS. So ignore the interfernce index remarks. :)

 

Still wouldn't expect ARM to settle on 6 or 11 if I had a spike like that at 2450 Mhz

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