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Occasional Contributor II
Posts: 31
Registered: ‎10-16-2013

Air monitor scanning time

Hi,

 

Do you know how often and how long scan AM's other channels?

 

Thanks,

Dusan

MVP
Posts: 1,405
Registered: ‎05-28-2008

Re: Air monitor scanning time

info:

http://www.arubanetworks.com/techdocs/ArubaOS_63_Web_Help/Content/ArubaFrameStyles/ARM/ARM_Profiles.htm

 

http://www.arubanetworks.com/techdocs/ArubaOS_60/UserGuide/ARM.php

 

https://arubanetworkskb.secure.force.com/pkb/articles/FAQ/What-is-channel-quality-aware-ARM-How-is-it-configured

 

https://arubanetworkskb.secure.force.com/pkb/articles/HowTo/R-1281

 

Here is an article about the difference between Air Monitors and Regular Access Points:  http://www.arubanetworks.com/pdf/technology/tb_air_monitors.pdf

 

Please refer to the thread here:  http://community.arubanetworks.com/t5/Access-Points/Change-mode-from-Air-Monitor-to-AP/td-p/7790 to see how to change to Air Monitor and back to an access point.

 

 

 

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MVP
Posts: 1,405
Registered: ‎05-28-2008

Re: Air monitor scanning time

ARM min-scan-time is set by default to 8. That means that every valid channel in the band must be scanned 8 times before the AP can decide to move there, even though it may find that the channel is better earlier.

 

To speed up convergence, you can lower this parameter, however, it is set to this default for a reason. Assuming a default ARM scan interval of 10 seconds and scan time of 110 milliseconds and 2.4GHz with 11 valid channels in the regulatory domain, it takes ~15 minutes for the network to start to converge.

 

(10 seconds times 11 equals 110 seconds. You need 8 passes, which is 880 seconds. Divide by 60, which is ~15 minutes.)

*****************2Plus Wireless Solutions****************************
Aruba Airheads - Powered By community for empower the community
************ Don't Forget to Kudos + me,If i helped you******************
Occasional Contributor II
Posts: 31
Registered: ‎10-16-2013

Re: Air monitor scanning time

It means that AM and AP have the same timers? 10 seconds for 110 ms? I thought that AM do faster scanning then AP.

 

There is also another question. Do AM participate also for interferecne scanning or is it only for security.

 

Dusan

Guru Elite
Posts: 20,819
Registered: ‎03-29-2007

Re: Air monitor scanning time

Dusan,

 

To build on what Kdisc98 mentioned...it depends.  The "show ap monitor scan-info ap-name <name of ap>" command will show you how long an access point remains on each channel:  http://www.arubanetworks.com/techdocs/ArubaOS_64_Web_Help/Web_Help_Index.htm#ArubaFrameStyles/New_WIP/TotalWatch_Administratio.htm

 

How long an Air Monitor stays on each channel (the dwell time) depends on what kind of channel it is:

 

Here are the default dwell times for an Air Monitor (all-reg-domain setting):

 

Active Channel (channel with clients on it) - 500 milliseconds

Regulatory domain channels with no clients - 250 milliseconds

Regulatory domain channels outside of current regulatory domain - 200 milliseconds

Rare Channels - 100 milliseconds - (only active if scan mode is set to rare)

DOS or channel with a rogue access point - 500 milliseconds

 

 

(7240) #show ap monitor scan-info ap-name Office-225


WIF Scanning State: wifi0: 9c:1c:12:90:59:50
---------------------------------------------
Parameter                      Value
---------                      -----
Probe Type                     am
Phy Type                       80211a-VHT-80
Scan Mode                      all-reg-domain
Scan Channel                   yes
Disable Scanning               no
RegDomain Scan Completed       yes
DOS Channel Count              0
Current Channel                161E
Current Scan Channel           161E
Current Channel Index          27
Current Scan Start Milli Tick  162479200
Current Dwell Time             250
Current Scan Type              all-reg-domain

Scan-Type-Info
---------------
Info-Type          Active  Reg-domain  All-reg-domain  Rare  DOS
---------          ------  ----------  --------------  ----  ---
Dwell Times        500     250         200             100   500
Last Scan Channel  36E     161E        46E             0     0



Colin Joseph
Aruba Customer Engineering

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Occasional Contributor II
Posts: 31
Registered: ‎10-16-2013

Re: Air monitor scanning time

Thank you.

 

Dusan

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