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Occasional Contributor I
Posts: 5
Registered: ‎04-13-2009

ARM HT Empty Channel Trigger new

I have one AP which is changing channels all the time with a reason of "M: Empty Channel" as displayed below:

Aruba3400) #show ap arm history ap-name Bulc-Expo-1er-Mat-Couverture

Interface :wifi0
ARM History
-----------
Time of Change Old Channel New Channel Old Power New Power Reason
-------------- ----------- ----------- --------- --------- ------
2011-03-16 15:12:20 52+ 124 24 24 M
2011-03-16 15:06:20 36+ 52- 24 24 M
2011-03-16 15:01:27 124+ 36 24 24 M
2011-03-16 14:51:25 52+ 124 24 24 M
2011-03-16 14:44:50 36+ 52- 24 24 M
2011-03-16 14:39:57 124+ 36 24 24 M
2011-03-16 14:29:55 52+ 124 24 24 M
2011-03-16 14:23:52 36+ 52- 24 24 M
2011-03-16 14:18:33 124+ 36 24 24 M
2011-03-16 14:08:31 52+ 124 24 24 M
2011-03-16 14:03:15 36+ 52- 24 24 M
2011-03-16 13:58:10 124+ 36 24 24 M
2011-03-16 13:48:07 52+ 124 24 24 M
2011-03-16 13:42:32 36+ 52- 24 24 M
2011-03-16 13:35:22 124+ 36 24 24 M
2011-03-16 13:25:20 52+ 124 24 24 M
2011-03-16 13:20:28 36+ 52- 24 24 M
2011-03-16 13:15:31 124+ 36 24 24 M
2011-03-16 13:05:28 52+ 124 24 24 M
2011-03-16 12:57:42 36+ 52- 24 24 M
2011-03-16 12:51:10 124+ 36 24 24 M
2011-03-16 12:41:08 52+ 124 24 24 M
2011-03-16 12:35:06 36+ 52- 24 24 M
2011-03-16 12:29:53 124+ 36 24 24 M
2011-03-16 12:19:51 52+ 124 24 24 M
2011-03-16 12:12:53 36+ 52- 24 24 M
2011-03-16 12:05:08 124+ 36 24 24 M
2011-03-16 11:55:07 52+ 124 24 24 M
2011-03-16 11:50:25 36+ 52- 24 24 M
2011-03-16 11:43:04 124+ 36 24 24 M
2011-03-16 11:33:03 52+ 124 24 24 M
2011-03-16 11:27:44 36+ 52- 24 24 M

1 - what is the signification of the reason M: Empty Channel ?
2 - what can produce this ?
3 - can this affect users connectivity ?

Thanks
Guru Elite
Posts: 20,759
Registered: ‎03-29-2007

Re: ARM HT Empty Channel Trigger new

1. Empty Channel means there is an available channel for the AP to go to so the AP changes channel to that
2. See #1
3. If you have "ARM Client-Aware" enabled, it will not change channel when clients are associated
4. What version of code is this?


Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I
Posts: 5
Registered: ‎04-13-2009

Re: ARM HT Empty Channel Trigger new

Thanks Colin,

I am running Version 5.0.3.0.

I was wondering since those frequent changes are always followed by the message:

KERNEL(Bulc-Expo-1er-Mat-Couverture@172.20.186.151): RESTARTING ALL TX

and since it is on the 5 Ghz band with have DFS holding beacons for 1 min and it could prevent new client to connect for a short time.
Guru Elite
Posts: 20,759
Registered: ‎03-29-2007

Re: ARM HT Empty Channel Trigger new

What is your regulatory domain, what channels are you operating on, and what access point type are you using?

You can find all three out with the command:

show ap allowed-channels ap-name


Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

Occasional Contributor I
Posts: 5
Registered: ‎04-13-2009

Re: ARM HT Empty Channel Trigger new

Regulatoty domain is CH (Switzerland)

We are using channel 1,6 and 11 for compatibility.

Since last post I have upgraded to 5.0.3.1 and the symptoms have
disapeared.

It seems it was a minor bug of version 5.0.3.0.

Below the arm history of this AP which shows correct behaviour now

(Aruba3400) #show ap arm history ap-name Bulc-Expo-1er-Mat-Couverture

Interface :wifi0
Interface :wifi1
ARM History
-----------
Time of Change Old Channel New Channel Old Power New Power Reason
-------------- ----------- ----------- --------- --------- ------
2011-03-22 17:59:59 11 11 18 21 P+
2011-03-20 09:29:11 11 11 21 18 P-
2011-03-20 07:42:18 11 11 18 21 P+
2011-03-18 22:45:50 11 11 15 18 P+
2011-03-18 22:31:55 11 11 12 15 P+
2011-03-18 22:25:06 11 11 9 12 P+
2011-03-18 22:20:32 6 11 9 9 I
2011-03-18 10:23:44 6 6 12 9 P-
2011-03-17 18:35:39 6 6 15 12 P-
2011-03-17 11:00:51 6 6 18 15 P-
2011-03-17 09:37:46 6 6 21 18 P-
I: Interference, R: Radar detection, N: Noise exceeded, E: Error threshold exceeded, INV: Invalid Channel, G: Rogue AP Containment, M: Empty Channel, P+: Increase Power, P-: Decrease Power, OFF: Turn off Radio, ON: Turn on Radio

Thanks Colin and kind regards
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