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Location-based mobile app development and Bluetooth-based asset tracking with Meridian. Gathering analytics and business intelligence from Wi-Fi with Analytics and Location Engine (ALE).
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I've got a customer with busy channels. How do you go about troubleshooting that?

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  • 1.  I've got a customer with busy channels. How do you go about troubleshooting that?

    Posted Jun 23, 2014 12:34 PM

    I've got a customer with busy channels. How do you go about troubleshooting that?

     

    According to the dashboard, there's not much interference.  What could be causing this?  How would one confirm/troubleshoot what the source of the problem is?



  • 2.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?

    Posted Jun 23, 2014 01:14 PM
    If you have sticky devices attached transmitting at very low data rate , too many APs , using 40 or 80 MHz channels when there's too many APs



  • 3.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?

    Posted Jun 23, 2014 01:16 PM
    Run the following to a couple of your APs in question:
    show ap arm rf-summary ap-name
    Show ap arm history ap-name


  • 4.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?

    Posted Jun 23, 2014 02:39 PM

     

    #show ap arm rf-summary ap-name 

     

    Channel SummaryPreview

    ---------------

    channel  retry  phy-err  mac-err  noise  util(Qual)    cov-idx(Total)  intf_idx(Total)

    -------  -----  -------  -------  -----  ----------    --------------  ---------------

    36       0      0        0        92     0/0/0/0/90    8/0(8)          42/0//0/0(42)

    40       0      0        0        92     12/0/2/0/90   0/0(0)          0/34//0/0(34)

    44       0      0        0        93     12/0/2/0/89   12/0(12)        60/0//0/0(60)

    48       0      0        0        92     12/0/2/0/90   0/0(0)          0/20//0/0(20)

    149      0      0        0        93     5/1/0/0/89    3/0(3)          28/0//0/0(28)

    153      0      0        0        93     12/0/2/0/90   0/0(0)          0/14//0/0(14)

    157      0      0        0        93     12/0/11/0/90  8/0(8)          15/2//0/0(17)

    161      0      0        0        93     13/1/2/0/89   0/0(0)          5/5//0/0(10)

    165      0      0        0        96     12/0/2/0/90   0/0(0)          0/3//0/0(3)

    1        0      0        0        90     0/0/0/0/76    18/0(18)        178/50//134/2(364)

    6        0      0        0        91     97/72/2/2/77  11/0(11)        126/56//15/30(227)

    11       0      0        1        96     60/48/2/0/90  9/0(9)          81/21//0/2(104)

     

    Columns:util(Qual): ch-util/rx/tx/ext-ch-util/quality

     

    HT Channel Summary

    ------------------

    channel_pair  Pairwise_intf_index

    ------------  -------------------

    149-153       42

    36-40         76

    157-161       27

    44-48         80

     

    Interface Name           :wifi0

    Current ARM Assignment   :157+/24

    Covered channels a/g     :3/0

    Free channels a/g        :5/0

    ARM Edge State           :enable

    Last check channel/pwr   :3m:37s/5m:22s

    Last change channel/pwr  :1h:2m:48s/1h:2m:48s

    Next Check channel/pwr   :1m:50s/56s

    Assignment Mode          :Single Band

     

    Interface Name           :wifi1

    Current ARM Assignment   :11/12

    Covered channels a/g     :0/3

    Free channels a/g        :0/0

    ARM Edge State           :enable

    Last check channel/pwr   :4m:3s/2m:1s

    Last change channel/pwr  :11m:48s/6m:38s

    Next Check channel/pwr   :11s/5m:50s

    Assignment Mode          :Single Band

     

     

     show ap arm history ap-name 

     

    Interface :wifi0

    ARM History

    -----------

    Time of Change       Old Channel  New Channel  Old Power  New Power  Reason

    --------------       -----------  -----------  ---------  ---------  ------

    2014-06-22 22:56:06  157+         157+         21         24         P+

    2014-06-19 12:38:46  157+         157+         24         21         P-

    2014-06-19 12:36:34  36+          157+         24         24         I

    2014-06-19 12:25:22  161-         36+          24         24         M

    2014-06-19 11:31:24  36+          161-         24         24         I

    2014-06-19 11:05:12  161-         36+          24         24         I

    2014-06-19 09:32:47  36+          161-         24         24         I

    2014-06-19 08:59:15  161-         36+          24         24         I

    2014-06-18 23:47:11  36+          161-         24         24         I

    2014-06-18 23:12:36  161-         36+          24         24         I

    2014-06-18 22:42:58  40-          161-         24         24         I

    2014-06-18 21:59:56  161-         40-          24         24         I

    2014-06-18 20:52:23  48-          161-         24         24         I

    2014-06-18 20:48:16  48-          48-          24         18         P-

    2014-06-18 20:47:48  40-          48-          24         24         I

    2014-06-18 20:03:32  161-         40-          24         24         I

    2014-06-18 18:44:31  40-          161-         24         24         I

    2014-06-18 17:49:42  161-         40-          24         24         I

    2014-06-18 17:29:27  40-          161-         24         24         I

    2014-06-18 16:26:34  161-         40-          24         24         I

    2014-06-18 13:16:25  161-         161-         21         24         P+

    2014-06-18 13:02:02  161-         161-         18         21         P+

    2014-06-18 12:55:20  161-         161-         15         18         P+

    2014-06-18 12:48:50  161-         161-         12         15         P+

    2014-06-18 12:45:54  36+          161-         12         12         I

    2014-06-18 12:29:05  36+          36+          18         12         P-

    2014-06-18 12:08:46  36+          36+          24         18         P-

    2014-06-18 12:05:58  161-         36+          24         24         I

    2014-06-18 11:29:39  161-         161-         21         24         P+

    2014-06-18 11:25:21  161-         161-         18         21         P+

    2014-06-18 11:18:31  161-         161-         15         18         P+

    2014-06-18 10:56:41  161-         161-         12         15         P+

    Interface :wifi1

    ARM History

    -----------

    Time of Change       Old Channel  New Channel  Old Power  New Power  Reason

    --------------       -----------  -----------  ---------  ---------  ------

    2014-06-23 13:11:56  11           11           9          12         P+

    2014-06-23 12:34:55  11           11           12         9          P-

    2014-06-23 12:29:42  11           11           9          12         P+

    2014-06-23 11:40:09  11           11           12         9          P-

    2014-06-23 11:32:23  11           11           9          12         P+

    2014-06-23 10:49:46  11           11           12         9          P-

    2014-06-23 10:43:16  11           11           9          12         P+

    2014-06-23 10:12:29  11           11           12         9          P-

    2014-06-23 10:08:01  11           11           9          12         P+

    2014-06-23 10:02:11  11           11           12         9          P-

    2014-06-23 09:56:31  11           11           18         12         P-

    2014-06-23 09:01:22  11           11           15         18         P+

    2014-06-23 08:54:42  11           11           12         15         P+

    2014-06-23 08:48:28  11           11           9          12         P+

    2014-06-23 08:31:57  11           11           12         9          P-

    2014-06-23 08:25:57  11           11           9          12         P+

    2014-06-23 08:21:10  11           11           12         9          P-

    2014-06-23 08:13:40  11           11           9          12         P+

    2014-06-23 08:06:08  11           11           15         9          P-

    2014-06-23 08:00:10  11           11           21         15         P-

    2014-06-23 07:53:18  11           11           18         21         P+

    2014-06-23 07:42:58  11           11           15         18         P+

    2014-06-23 07:26:45  11           11           12         15         P+

    2014-06-23 07:17:28  11           11           9          12         P+

    2014-06-23 07:09:35  11           11           12         9          P-

    2014-06-23 07:05:18  11           11           15         12         P-

    2014-06-23 06:58:54  11           11           12         15         P+

    2014-06-23 06:52:14  11           11           9          12         P+

    2014-06-23 06:44:29  11           11           12         9          P-

    2014-06-23 06:36:40  11           11           9          12         P+

    2014-06-23 06:32:17  11           11           12         9          P-

    2014-06-23 06:28:07  11           11           9          12         P+

    I: Interference, R: Radar detection, N: Noise exceeded, Q: Bad Channel Quality E: Error threshold exceeded, INV: Invalid Channel, G: Rogue AP Containment, M: Empty Channel, P+: Increase Power, P-: Decrease Power, 40INT: 40MHZ intol detected on 2.4G, NO40INT: 40MHz intol cleared on 2.4G, OFF: Turn off Radio, ON: Turn on Radio

     



  • 5.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?

    EMPLOYEE
    Posted Jun 23, 2014 03:10 PM

    There could be many items which cause channel utilization - 

     

    - Client Usage

    - Other APs/Rogues around the AP

    - Interference sources

    - in a dense deployment, too many APs can hear each other or APs are receiving data which is can be disabled

     

    In order to find root cause, it is adviseable to open up a support case and start there.  

     

    For more help here, it would be good to know how many APs are out here are if you are in a dense deployment and if the util. is on 2.4, 5 or both?

     

    If you have Airwave, we have an extrodinarily useful dashboard called "RF Capacity" which can plot out the radios over a trailing 7 days to show peak utilization as compared to client count with the ability to drill down for more root cause analysis!



  • 6.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?

    Posted Jun 23, 2014 03:29 PM
    It looks like you have issues on your 5 Ghz channels a lot of interference .
    are you using 40 Mhz channels ?
    Do you have a very dense setup ?


  • 7.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?

    Posted Jun 23, 2014 03:36 PM
      |   view attached

    Thank you for the reponses, guys.

     

    How would I know if I'm using 40 MHz channels?

     

    Interestingly, the dashboard doesn't show that I have much interference.  



  • 8.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?

    EMPLOYEE
    Posted Jun 23, 2014 03:38 PM

    In the show ap active output, look at the 5GHz column.  If it says "VHT", you're on 80.  If it says HT, you're on 40.

     

    HT stands for high throughput

    VHT stands for very high throughput



  • 9.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?

    Posted Jun 23, 2014 03:40 PM

    It's 40 MHz.  Also, all of the clients are dropping after a few minutes of association. When they re-associate, they work fine for a few minutes and then drop.



  • 10.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?
    Best Answer

    Posted Jun 23, 2014 03:56 PM

     

    If you see + or a - next to the channel that means you are using 40 Mhz and 80 Mhz you will see an E next to the channel

    2014-06-23 15_53_03-Re_ I've got a customer with busy channels. How do you go about troubleshooting .png



  • 11.  RE: I've got a customer with busy channels. How do you go about troubleshooting that?

    EMPLOYEE
    Posted Jun 23, 2014 05:03 PM
    @aswokei wrote:

    I've got a customer with busy channels. How do you go about troubleshooting that?

     

    According to the dashboard, there's not much interference.  What could be causing this?  How would one confirm/troubleshoot what the source of the problem is?

    Reasons for Channel Busy in order of probability:

     

    - Broadcasts Enabled--  Solution...Enable "Drop Broadcast and Multicast" on ALL your Virtual APs

    - Access Point Power too High-  Solution...In your ARM Profile, start with the min TX at 12 and your max TX at 18

    - Too much management traffic-  Solution...Reduce your AP power or disable lower rates in the SSID>Advanced Profile:  http://community.arubanetworks.com/t5/Unified-Wired-Wireless-Access/High-density-disable-low-data-rates-or-not/m-p/150890/highlight/true#M31991

    - Too Many SSIDs - Solution:....have only 3 SSIDs or less.  Combine devices with similar encryption types and use roles to separate one client's behavior from another.  Have your Virtual APs only broadcast on bands that your clients will use...e.g. if you have phones that only use b/g, make sure the Virtual APs allowed bands is only for g.

     

    How to see channel busy for each access point?  Run the command below before and after making changes to measure the impact

     

    (Controller) #show ap debug radio-stats ap-name Office-135 radio 1 | include usy             
Channel Busy 1s                     4
Channel Busy 4s                     3
Channel Busy 64s                    3
Ch Busy perct @ beacon intvl        3 4 3 3 3 3 3 3 3 3 4 0 3 3 3 13 10 4 3 0 4 3 3 3 4 3 3 3 3 3

     Replace "Office-135" with the name of your access point.  Also radio 1 is 2.4ghz (g) and Radio 0 is 5ghz (802.11a)