Wireless and RF

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Occasional Contributor II

default ARM configuration tremendous FAIL

I've resetted the aruba controller to configure it from scratch.
After some weeks of the reset i noticed that most of the APs are emitting at 9 dBm. I thought let it be.. aruba controller knows what it is doing..
But last week somebody noticed that there is a meeting room with a poor wifi signal like -85 or less and where the client roams from two APs randomly (depending on if the blinds ar up or down xD - metallic blinds-). The room is between two APs but with the aps emitting at 9 dBm there was conection at only 1Mbps.

Now I set the min and max Tx power of the APs to 15 and 20 as i had befor the controller reset. And it seems the problems disapeared.

Ok, the facility is a synchrotron and i have about 7 aps scattered on the big donnut. Some aps see each other directly, in this case I understand that they transmit at 9 dBm if they are on the same channel. But even the APs that are on a separate channel were autoconfigured to send at 9 dBm.

I can't understand why, any hint about this?
Guru Elite

show ap arm rf-summary ap-name <name of ap>

The "show ap arm rf-summary ap-name" command will tell you exactly what an AP sees are on its other channels and why it chose the channel that it is on:

(Aruba800-4) #show ap arm rf-summary ap-name Bridge-CAP                                                          

Channel Summary
---------------
channel retry low-speed non-unicast frag bwidth phy-err mac-err noise cov-idx intf_idx
------- ----- --------- ----------- ---- ------ ------- ------- ----- ------- --------
161 0 0 0 0 0 0 0 0 0/0 0/69//0/0
1 0 0 0 0 0 0 0 0 0/0 70/55//0/0
48 0 0 0 0 0 0 0 0 0/0 0/0//0/0
165 0 0 0 0 0 0 0 0 0/0 0/0//0/0
5 0 0 0 0 0 0 0 0 0/0 18/121//0/0
6 0 0 0 0 0 0 0 0 0/0 78/70//0/0
7 0 0 0 0 0 0 0 0 0/0 0/137//0/0
11 17 0 77 0 100 0 15 91 7/0 87/44//0/0
149 0 0 0 0 0 0 0 0 0/0 0/0//0/0
36 0 0 0 0 3 0 0 98 11/0 0/0//0/0
153 0 0 0 0 0 0 0 0 0/0 0/66//0/0
40 0 0 0 0 0 0 0 0 0/0 0/0//0/0
157 0 0 0 0 0 0 0 0 0/0 207/0//0/0
44 0 0 0 0 0 0 0 0 0/0 0/0//0/0
HT Channel Summary
------------------
channel_pair Pairwise_intf_index
------------ -------------------
1-5 264
7-11 268
149-153 66
36-40 0
157-161 276
44-48 0

Interface Name :wifi0
Current ARM Assignment :36+/9
Target Coverage Index :10
Covered channels a/g :1/0
Free channels a/g :8/0
ARM Edge State :enable
Last check channel/pwr :1d:22h:44m:28s/4m:14s
Last change channel/pwr :1d:22h:44m:28s/1d:13h:40m:10s
Next Check channel/pwr :0s/3m:20s

Interface Name :wifi1
Current ARM Assignment :11/21
Target Coverage Index :10
Covered channels a/g :0/1
Free channels a/g :0/2
ARM Edge State :disable
Last check channel/pwr :5m:58s/3m:38s
Last change channel/pwr :5m:58s/1d:22h:44m:28s
Next Check channel/pwr :25s/4m:6s



Check out the attached Troubleshooting Cheatsheet starting on page 8 for information about this command and how APs choose their channel. Access points need to be mounted with antennas oriented properly to adjust channel and power correctly. If too many access points are on the same channel, like when you are in a dense deployment, they will drop their power to the minimum. These could be your access points, or other interferring access points. They will lower their power if they see to many access points and you can increase to minimum tx power to mitigate that.. just like you did.


Colin Joseph
Aruba Customer Engineering

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