Wireless Access

I was wondering if its okay if i use a higher trasmit power for airmonitors.
Normally for clients i wolud use 18 dbm for many reasons.
But for air monitors this would apply? I mean there wont ne issues with roaming, and things like that(i would like that maybe the ait monitoring area could reach a little farther.

Also i would like to know what the rssi that is needed so the air monitorbcan do all his job just fine. For example if im serving a client i do my site survey and i use no more than -65dbm. But how does this apply to air monitors. I know that you dont need the same signal strengh as you are not serving clients.

Cheers
Carlos

AMs do not transmit. The majority of AM monitoring is done at legacy or management frame rates, and that coverage is very far. The back of the napkin calculation is one AM for every 4 or 5 APs.

That density is mainly for intrusion protection.

How do I know the range they cover?

Please see the document here http://www.arubanetworks.com/pdf/technology/tb_air_monitors.pdf?repo=tech

Hello Collin
Thabks for yoir asnwer. I have seen that documebt before but it does not tell you how many ams you would need in a building or how to valculate it and where to place it. So how do you know how many ans where to place them if i dont know the range it covers. With a nirmal ap i can know the range it cover by looking at the signal strengh of the ap withba flike for example. How would it work with AMS then?

VisualRF (the newest one in shown below), will allow you to plan with Air Monitors:

Nice colin!!!!!
Ill go and download it right now!
Thanks man!!!!

Carlos,

 

The old VisualRF also let you plan with Air Monitors.  I was just showing you a screenshot of the new one in Airwave.  If you already have the laptop VisualRF, just use that...

Thanks Collin
One last queation. How would you do this if the client does not count with maps or anything to uploud to the visual rf????

If you know how many access points, AMs are 1/4 or 1/5 of the total AP count.

That doesnt sounds really exact. In this last survey in one of the maps ibwas doing the relation was 1 am for every 2 aps( because of walls and stuff)

Guess in other scenarios would be like that.
Sounds thar is a bit hard.

It woukd be nicer i guess that if you could do it like puttong one ap as a srving ap and check somehting like the rssi lime on -80 is still fine or something like that.

 

- If you are only doing IDS detection, you don't specifically need AMs.  If you are doing IDS Protection, like disabling rogue access points, you need AMs, because APs serving clients cannot serve clients and do IPS at the same time effectively.  

- If you put a floorplan in VisualRF, instead of setting it to APs, you can set it to Air monitors and it will tell you how many.  IDS/IPS really occurs at the management frame level and by default that is 1 or 2 megs on the 2.4ghz side and 5megs on the 5ghz side.  Those management frames can travel very far and be seen very far when sent at the lowest rates (300 feet or more).  Air monitors are typically deployed using square footage, because Air Monitors do not send any RF traffic they only "see" that traffic, so you cannot really survey for them effectively.

If you have walls, you face the same challenges like APs where you have to decide where to put them, based on coverage.  That is where VisualRF comes into play.  Draw your walls, set the coverage to Air Monitors instead of APs and see how it looks on the diagram.

 

 

 

 

Thanks again for your time Colin!!! :) 

 

Cheers

Carlos