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Access network design for branch, remote, outdoor, and campus locations with HPE Aruba Networking access points and mobility controllers.
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Troubleshooting a wifi problem

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  • 1.  Troubleshooting a wifi problem

    Posted Oct 14, 2013 07:23 AM

    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

     

     

     

     



  • 2.  RE: Troubleshooting a wifi problem

    EMPLOYEE
    Posted Oct 14, 2013 07:31 AM

    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.

     



  • 3.  RE: Troubleshooting a wifi problem

    Posted Oct 14, 2013 08:12 AM

    Still stuck on 1... :smileyfrustrated:

     

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

     

    Cheers

     

     



  • 4.  RE: Troubleshooting a wifi problem

    EMPLOYEE
    Posted Oct 14, 2013 08:45 AM

    @$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....

     



  • 5.  RE: Troubleshooting a wifi problem

    Posted Oct 14, 2013 08:46 AM

    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.

     

     



  • 6.  RE: Troubleshooting a wifi problem

    EMPLOYEE
    Posted Oct 14, 2013 08:51 AM

    @$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.

     



  • 7.  RE: Troubleshooting a wifi problem

    Posted Oct 15, 2013 10:05 AM

    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.



  • 8.  RE: Troubleshooting a wifi problem

    Posted Oct 15, 2013 12:56 PM

    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



  • 9.  RE: Troubleshooting a wifi problem

    Posted Oct 15, 2013 01:12 PM

    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



  • 10.  RE: Troubleshooting a wifi problem

    EMPLOYEE
    Posted Oct 15, 2013 01:12 PM

    @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.