Wireless Access

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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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Do AP go back to the original channel after rader detected?

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  • 1.  Do AP go back to the original channel after rader detected?

    Posted Nov 12, 2013 01:57 AM

    Hi

     

    When Rader is detected on 5GHz, channel is changed.
    After the rader is gone out, do we go back to the original channel?

    If so, can we stop it?

    We are wondering if the circumstance is very bad due to frequent change.


    In below log, AP cnahged cahnnel from 100-1-4 to 124-128 and to 108-112.
    Then it changed to 124-128 again. Is this expected bahaivor?

     

    Oct 18 16:19:16  sapd[770]: <404076> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: Radar detected on interface wifi0, channel 100, typeid 18
    Oct 18 16:19:16  sapd[770]: <404088> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM HT Radar Detected Trigger Current Channel old 100-104 new 124-128/8
    Oct 18 16:20:16  KERNEL(4FQ-GYW-AP03@172.26.129.172): RESTARTING ALL TX
    Oct 18 16:32:14  sapd[770]: <404050> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM C 124 PER 0 MER 95 FRR 0 50-30
    Oct 18 16:32:15  sapd[770]: <404089> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM HT Error Threshold Trigger Current Channel old 124-128 new 108-112/7
    Oct 18 16:32:45  sapd[770]: <404050> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM C 108 PER 0 MER 100 FRR 0 50-30
    Oct 18 16:32:46  sapd[770]: <404089> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM HT Error Threshold Trigger Current Channel old 108-112 new 124-128/7

     

    Regards

    Simon



  • 2.  RE: Do AP go back to the original channel after rader detected?

    EMPLOYEE
    Posted Nov 12, 2013 07:21 AM
    @sai45mon10 wrote:

    Hi

     

    When Rader is detected on 5GHz, channel is changed.
    After the rader is gone out, do we go back to the original channel?

    If so, can we stop it?

    We are wondering if the circumstance is very bad due to frequent change.


    In below log, AP cnahged cahnnel from 100-1-4 to 124-128 and to 108-112.
    Then it changed to 124-128 again. Is this expected bahaivor?

     

    Oct 18 16:19:16  sapd[770]: <404076> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: Radar detected on interface wifi0, channel 100, typeid 18
    Oct 18 16:19:16  sapd[770]: <404088> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM HT Radar Detected Trigger Current Channel old 100-104 new 124-128/8
    Oct 18 16:20:16  KERNEL(4FQ-GYW-AP03@172.26.129.172): RESTARTING ALL TX
    Oct 18 16:32:14  sapd[770]: <404050> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM C 124 PER 0 MER 95 FRR 0 50-30
    Oct 18 16:32:15  sapd[770]: <404089> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM HT Error Threshold Trigger Current Channel old 124-128 new 108-112/7
    Oct 18 16:32:45  sapd[770]: <404050> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM C 108 PER 0 MER 100 FRR 0 50-30
    Oct 18 16:32:46  sapd[770]: <404089> <WARN> |AP 4FQ-GYW-AP03@172.26.129.172 sapd|  AM d8:c7:c8:45:e0:50: ARM HT Error Threshold Trigger Current Channel old 108-112 new 124-128/7

     

    Regards

    Simon

    Simon,

     

    By law, the access point cannot go back to the original channel for 30 minutes.  According to that log, it did not go back to the same channel, but it changed channel serveral times because of severe interference.  The error threshold is triggered when the noise floor falls below a certain threshold (by default it is 65).



  • 3.  RE: Do AP go back to the original channel after rader detected?

    Posted Nov 12, 2013 09:12 AM
    Hi Cjoseph

    Thanks for your comment.
    Can you configure not to go back to the original channel and stay in the current channel?

    Regards
    Simon


  • 4.  RE: Do AP go back to the original channel after rader detected?

    EMPLOYEE
    Posted Nov 12, 2013 09:29 AM

    Based on the log, it is changing channel due to the error rate threshold in the ARM profile.  That is typically 50%, you can increase it from 50% so that it will only change if there is much more interference/errors on the channel, but that means the access point will stay on a very, very bad channel.

     

    If it changes channel because of radar, it will NOT go back within 30 minutes.  If it changes because of error rate, it will wait at least 30 seconds (Error Rate wait time in the ARM profile) until it changes to another channel.  Do you want the access point to stay on a bad channel?



  • 5.  RE: Do AP go back to the original channel after rader detected?

    Posted Nov 12, 2013 10:14 AM

    Hi cjoseph

     

    I didn't realize the channel changes due to the error rate. I will check the ARM profile.

    I thought it changes due to radar as the log says the rader. 

     

    If the reader changes the channel, can I configure not to go back to the original channe after 30 minutesl?

    I think that the channel changed by a reader may not be changed by same rader again.

     

    Regards

    Simon



  • 6.  RE: Do AP go back to the original channel after rader detected?

    EMPLOYEE
    Posted Nov 12, 2013 10:21 AM

    sai45mon10,

     

    What is your general problem?  You have severe interference on a few channels, that is why it keeps changing channel.  You also possibly have radar on one channel.  The AP WILL stay off of that channel for 30 minutes and NOT change back to it.

     

    Do you need to run your WLAN on those channels,  or can you choose better channels?  Your general approach might be to uncheck those channels from the regulatory domain profile so that the access points do not change to them, because they are bad.  Unless you can detect and remove the source of interference, you probably do not want to run your WLAN on those channels..



  • 7.  RE: Do AP go back to the original channel after rader detected?

    Posted Nov 15, 2013 05:12 AM

    Hi CJ

     

    I just wanted to confirm the customer question if AP go back to the original channel 30 minutes later after reader detected because they thought channels were changed by radar only.

    Now I understand it doesn't go back even 30 minute later.

    And thanks for advice this circumstance have interference besides radar.

     

    Regards

    Simon