Security, WIDS/WIPS and Aruba ECS

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Regular Contributor I
Posts: 179
Registered: ‎08-29-2008

Quick Change Artist (Air Monitor to AP change)

I'm troubleshooting client roaming issues which brings me to this question...

An AP is in "Air Monitor" mode, how long should it take it to recognize that a Client is requesting authentication and switch to regular "AP" mode?

Since upgrading to 3.4 AOS, I've noticed that there are allot more APs in "Air Monitor" mode then there were before the upgrade... almost a third more.

If I'm walking down a hallway with a laptop pinging the local server, the laptop will pass 6 classrooms, which APs are in "Air Monitor" mode, and it will not associate with any of them. It will ether hang on for dear life to the first AP that it associated with, or just disconnect.
Guru Elite
Posts: 20,579
Registered: ‎03-29-2007

Air Monitor Mode


I'm troubleshooting client roaming issues which brings me to this question...

An AP is in "Air Monitor" mode, how long should it take it to recognize that a Client is requesting authentication and switch to regular "AP" mode?

Since upgrading to 3.4 AOS, I've noticed that there are allot more APs in "Air Monitor" mode then there were before the upgrade... almost a third more.

If I'm walking down a hallway with a laptop pinging the local server, the laptop will pass 6 classrooms, which APs are in "Air Monitor" mode, and it will not associate with any of them. It will ether hang on for dear life to the first AP that it associated with, or just disconnect.




Worlis Man,

APs in Air Monitor mode will not change to regular access points unless you have ARM Mode Aware checked. They also will not magically turn back into access points just because a client passes by. Did you manually make those APs Air monitors, or Are you using ARM Mode aware?


Colin Joseph
Aruba Customer Engineering

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Regular Contributor I
Posts: 179
Registered: ‎08-29-2008

Re: Quick Change Artist (Air Monitor to AP change)

Thanks Colin for the reply.

Yes, the "Mode Aware Arm:" is checked in one of my test ARM Profiles, which was active when I was testing out the roaming issue.

According to the UG, "Mode aware ARM can turn APs into Air Monitors if necessary, then turn those Air Monitors back into APs when they detect gaps in coverage."

So are you saying that if a user walks down a hallway that most of the APs are in "Air Monitor" mode, and I have the "Mode Aware Arm:" checked in the ARM Profile, the APs will not automatically switch back to AP mode?

If that's the case, I guess "Mode Aware Arm:" is worthless in a WVOIP environment.
Guru Elite
Posts: 20,579
Registered: ‎03-29-2007

ARM Mode-Aware


Thanks Colin for the reply.

Yes, the "Mode Aware Arm:" is checked in one of my test ARM Profiles, which was active when I was testing out the roaming issue.

According to the UG, "Mode aware ARM can turn APs into Air Monitors if necessary, then turn those Air Monitors back into APs when they detect gaps in coverage."

So are you saying that if a user walks down a hallway that most of the APs are in "Air Monitor" mode, and I have the "Mode Aware Arm:" checked in the ARM Profile, the APs will not automatically switch back to AP mode?

If that's the case, I guess "Mode Aware Arm:" is worthless in a WVOIP environment.




ARM Mode aware's intent is to determine if there is too much coverage in an area and turn off radios to reduce interference. IT takes time to do this. Just like you don't want APs changing channel all the time, you don't want them turning off and on all the time. It uses timers so that the process is gradual and not disruptive. Clients are not a trigger to determine coverage; the spectrum in an area, is. ARM Mode aware also turns off radios, not entire APs, so if there is enough coverage in the 2.4ghz, for example, it will turn off the 2.4ghz side of the radio, but the 5ghz side will continue to accept clients. It was not intended to be, and should not be depended on, to shut off radios where there are no clients, and turn them on when clients appear.


Colin Joseph
Aruba Customer Engineering

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

Regular Contributor I
Posts: 179
Registered: ‎08-29-2008

Re: Quick Change Artist (Air Monitor to AP change)

That explains why I'm having roaming issues now. :(
Guru Elite
Posts: 20,579
Registered: ‎03-29-2007

Roaming Issues

Worlis,

I would highly emphasize that you read Aruba's Validated Reference Guide for Roaming Devices here: http://www.arubanetworks.com/pdf/technology/DG_Roaming.pdf It gives you great deal of understanding how to Optimize the Aruba infrastructure for your devices.


Colin Joseph
Aruba Customer Engineering

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

Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: Quick Change Artist (Air Monitor to AP change)

I've actually begun to rethink the use of "mode aware ARM." It seems to turn off too many APs and actually seems to create coverage gaps, at least from a user perspective.

Do the ideal and acceptable coverage index knobs play any role in mode aware ARM?
Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: Quick Change Artist (Air Monitor to AP change)

Anyway we can get a feature request put it for manual overrides of an AP switching to an AM when "mode aware ARM" is on? I like the feature, but it would be nice to have some knobs associated with it.

For example, I have eight APs on one floor of a building...six of the APs were turned to AMs on both radios. I can see there are now coverage gaps in Airwave. In fact, the one AP125 we have on the floor in our "hotelling space" is an AM and the AP65 down the hall from it is an AP. Complete waste of the 125 as I now I don't have any .11n access on the floor.
Guru Elite
Posts: 20,579
Registered: ‎03-29-2007

ARM Mode Aware

Are you saying that you ONLY want APs to turn on and NOT turn off?

The coverage index does manipulate the ARM mode aware behavior, but you should test it before you use it, because every environment is different.


Colin Joseph
Aruba Customer Engineering

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

Aruba Employee
Posts: 509
Registered: ‎07-03-2008

Re: Quick Change Artist (Air Monitor to AP change)

Thanks Colin - I think a TAC case is probably appropriate to get a better feel for any coverage index changes.

For the feature request, I guess what I am saying is, let mode-aware ARM do its thing, but allow an admin to override on a per AP basis. So, if mode-aware turned a particular AP over to an AM, let me override that to turn it back to an AP and tell ARM not to change it back to an AM unless I reverse the override.
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