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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Ideal neighbors for AP

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  • 1.  Ideal neighbors for AP

    Posted Jan 22, 2019 10:24 AM

    We are seeing performance issues with our wireless network. Mostly around slow speeds as well as dropped connections. If I do a 

    show ap arm state ap-name command on an access point I'm getting the following results. To me, it seems like the AP is seeing too many other APs.

     

    AP:Hussey-Room-205 MAC:90:4c:81:f5:4c:20 Channel:1 EIRP:6.5 Max EIRP:24.5 Edge:disable

    Client Density:0 Valid neighbors: 25 Relevant neighbors: 13 Rx Probe Reports: 16833

    Moves(T/S):5/1 Sticky(T/S):0/0 Bandsteer(T/S):5/1 Loadbal(T/S):0/0

    Neighbor Data

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

    Name                IP Address    SNR (dB)  Path Loss (dB)  Channel/Pwr  Neighbor Density  Neighbors (R/T)  Relevant

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

    Hussey-Room-202     172.20.5.74   20        82              1/6.5        0                  12/21           Yes

    Hussey-Room-206     172.20.4.238  30        71              6/6.5        0                  9/20            Yes

    Hussey-Room-201     172.20.6.216  30        70              6/6.5        0                  10/28           Yes

    Hussey-Room-210     172.20.4.92   21        85              6/9.0        0                  7/20            Yes

    Hussey-Room-209     172.20.4.166  26        79              1/9.0        0                  11/20           Yes

    Hussey-Room-208     172.20.5.149  30        70              11/6.5       0                  11/19           Yes

    Hussey-Room-204     172.20.5.93   32        74              11/6.5       0                  10/19           Yes

    Hussey-Room-207     172.20.5.139  39        61              11/6.5       0                  10/28           Yes

    Hussey-Room-203     172.20.4.64   39        56              6/6.5        0                  11/25           Yes

    Hussey-Room-304     172.20.4.25   13        91              1/9.0        0                  10/31            

    Hussey-Room-405     172.20.5.204  11        88              6/6.5        0                  7/31            Yes

    Hussey-Room-306     172.20.4.241  8         95              6/9.0        0                  10/35            

    Hussey-Room-106     172.20.5.210  23        85              1/9.0        0                  7/26            Yes

    Hussey-Room-104     172.20.5.142  8         96              1/9.0        0                  10/29            

    Hussey-Room-408     172.20.5.105  23        78              1/9.0        0                  10/18           Yes

    Hussey-Room-102     172.20.5.88   7         95              11/6.5       0                  7/27             

    Hussey-Room-403     172.20.4.153  9         97              1/9.0        0                  9/28             

    Hussey-Room-302     172.20.4.49   7         96              11/9.0       0                  6/27             

    Hussey-Library      172.20.5.226  9         94              1/9.0        0                  7/20             

    Hussey-Room-409     172.20.5.183  12        90              6/9.0        0                  7/25             

    Hussey-Room-407     172.20.6.37   6         95              11/6.5       0                  13/34            

    Hussey-Room-404     172.20.5.170  1         98              6/6.5        0                  7/21             

    Hussey-Main-Office  172.20.6.84   7         86              6/9.0        0                  4/23            Yes

    Hussey-Room-406     172.20.6.235  5         100             11/6.5       0                  10/23            

    Hussey-Hall-220     172.20.6.197  11        93              1/9.0        0                  3/18             

    Legend: R = Relevant, T = Total,  Neighbor Density = (Overlap/Neighbor's Density/ Overlap to local density ratio/ Overlap to neighbor's density ratio)

     

    AP:Hussey-Room-205 MAC:90:4c:81:f5:4c:30 Channel:165 EIRP:18.0 Max EIRP:31.9 Edge:disable

    Client Density:0 Valid neighbors: 17 Relevant neighbors: 6 Rx Probe Reports: 16833

    Moves(T/S):0/0 Sticky(T/S):0/0 Bandsteer(T/S):0/0 Loadbal(T/S):0/0

    Neighbor Data

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

    Name             IP Address    SNR (dB)  Path Loss (dB)  Channel/Pwr  Neighbor Density  Neighbors (R/T)  Relevant

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

    Hussey-Room-209  172.20.4.166  22        97              153/18.0     0                  6/12             

    Hussey-Room-208  172.20.5.149  24        84              36/15.0      0                  5/11            Yes

    Hussey-Room-202  172.20.5.74   23        94              149/18.0     0                  3/13             

    Hussey-Room-206  172.20.4.238  34        84              48/18.0      0                  6/11            Yes

    Hussey-Room-201  172.20.6.216  31        84              40/18.0      0                  5/15            Yes

    Hussey-Room-203  172.20.4.64   45        63              157/18.0     0                  4/13            Yes

    Hussey-Room-210  172.20.4.92   20        101             161/18.0     0                  5/12             

    Hussey-Room-207  172.20.5.139  34        73              36/15.0      0                  4/15            Yes

    Hussey-Room-204  172.20.5.93   32        79              44/18.0      0                  4/8             Yes

    Hussey-Room-304  172.20.4.25   8         102             44/18.0      0                  4/13             

    Hussey-Room-409  172.20.5.183  10        105             149/18.0     0                  3/17             

    Hussey-Room-405  172.20.5.204  10        100             157/18.0     0                  4/15             

    Hussey-Room-306  172.20.4.241  9         100             36/18.0      0                  4/17             

    Hussey-Room-407  172.20.6.37   8         103             40/18.0      0                  1/16             

    Hussey-Library   172.20.5.226  8         102             157/18.0     0                  1/9              

    Hussey-Room-410  172.20.5.154  5         109             165/18.0     0                  3/10             

    Hussey-Room-104  172.20.5.142  7         102             44/18.0      0                  3/12             

     



  • 2.  RE: Ideal neighbors for AP

    EMPLOYEE
    Posted Jan 22, 2019 11:21 AM

    You are correct.  Ideally you don't want your access point to see any other access points on the same channel, because that will cause contention and reduce performance.  Realistically, in the 2.4ghz band you only have 3 channels, so you expect that.  You still want to reduce the transmit power on that band to as little as possible to provide coverage and only the clients that MUST be on 2.4ghz band will end up there.  With your 5ghz band, you also need to turn down the maximium transmit power and make sure that your access points do not see any other access points on the same channel with an SNR over 19 to avoid issues.  Hopefully you are also only running 20mhz channels in the 5ghz band.

     

    Procedure:

    - Record the output of "show ap arm state"

    - Do a speedtest on an access point

    - Make your transmit power adjustment

    - Wait 20 minutes for access points to scan their neighbors

    - Obtain the "show ap arm state" and see the difference

    - Do another speed test.



  • 3.  RE: Ideal neighbors for AP

    Posted Jan 22, 2019 11:38 AM

    I am only running 20 MHz in the 5GHz band. Should I also enable the dfs channels for 5GHz?



  • 4.  RE: Ideal neighbors for AP

    EMPLOYEE
    Posted Jan 22, 2019 11:47 AM

    You could do that.  I would first check:

     

    - That your clients support DFS channels

    - You do not have any radar in your area by downloading and running the Aruba Utilities App in the Google Play Store: https://play.google.com/store/apps/details?id=com.arubanetworks.arubautilities&hl=en_US



  • 5.  RE: Ideal neighbors for AP

    Posted Jan 25, 2019 10:11 AM

    Is there a min SNR that's acceptable for an AP to see the same channel? I have some of my AP's power turned down all the way on the 2.4 and they still see other WAPs with the same channel but with SNR's 15 and below. 



  • 6.  RE: Ideal neighbors for AP

    EMPLOYEE
    Posted Jan 25, 2019 10:55 AM

    Since the 2.4ghz band only has 3 non-overlapping channels, if you have your access points turned down to the minimum, you will simply have to accept the interference, and try to run most of your clients on 5ghz.

     

    An SNR of 15 and below is acceptable for connectivity.  Ideally not seeing APs on the same channel would provide the best performance.



  • 7.  RE: Ideal neighbors for AP

    Posted Jan 25, 2019 11:01 AM

    I'm going to look at turning some AP's into Air monitors to try and help with this. Since most clients run on the 5ghz channel, I don't need as much coverage for 2.4ghz.



  • 8.  RE: Ideal neighbors for AP

    EMPLOYEE
    Posted Jan 25, 2019 11:13 AM

    You should first try to:

     

    - Lower the Max Transmit power on the 5ghz band (anything that is 3 to 6 db above the 2.4ghz max transmit power is good)

    - Run 20mhz channels instead of 40mhz to give yourself 23 non-overlapping channels.

    - After about an hour, you can then compare the show ap arm state to see the difference.  With the changes above, it can be significant, without the administrative step of disabling access points.