Wireless Access

Hi,

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

Thanks,

Dusan

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

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.)

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

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

Thank you.

Dusan