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Diferrence Between RRM and Clean Air

Hello Everyone.

I want to say thank you for read my post.

 

Well I'm having some problems here, because I don't get the correct Idea for RRM & Clear Air. For me they do the same.

Can anyone explain me the differente?

 

Thank you.

 

 

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18 REPLIES 18

Yes.  This is the sole function of CleanAir.  

 

CleanAir has a small "list" of potential wireless interferrence signatures.  Once identifies, CleanAir will evaluate the strength of the interferrence and changes the channel and/or radio power if necessary.  

 

So far, this feature is unique in the industry.  

jiflorwi
Cisco Employee

There seems to be confusion regarding the difference between CleanAir and RRM.  They're two completely separate features.  For certain use cases they can collaborate when it makes sense.

 

CleanAir is a silicon level spectrum analyzer embedded into the radio chip set.  It's sole purpose in life is to detect, classify and measure sources of NON Wi-Fi radio signals.  To the Wi-Fi model - these simply appear as noise.

 

With or without CleanAir - RRM is reactive to noise.  The DCA channel algorithm measures Noise on a channel along with signal (which is our AP's transmissions) and interference (other AP's or Rogue's transmissions).  The Wi-Fi chipsets defines anything that can not be demodulated as Wi-Fi to be "Noise".

 

CleanAir is capable of identifying non-Wi-Fi sources of noise.  It does this by first pattern matching the radio waves at the physical layer, and then analyzing these using DSP modems to interrogate the sample.  It is extremely accurate and can easily identify multiple instances from even the same type of device (Bluetooth for instance - CleanAir can demodulate the link address - and allows us to keep track individually of multiple bluetooth sessions).

 

CleanAir can identify, evaluate severity (how much airtime am I losing because of this non-Wi-Fi device), and locate it on CMX and NCS maps.  It strictly investigates and analyzes NON-WI-FI.

 

RRM's DCA runs by default every 10 minutes.  With DCA alone - we would see the "NOISE" and if there is a better channel for that AP, change channels in reaction to it.

 

With CleanAir, identifying the Noise Source happens at the AP,

 

One example where CleanAir helps RRM is - ED-RRM .  Certain kinds of interference are extremely destructive and interrupt a Wi-Fi conversation immediately.  A video camera for instance, transmits at 100% duty cycle - it is always on.  Because Wi-Fi uses listen before talk to access the channel - this means every time the AP or the clients attempt to access the channel for transmit - they will hear that video camera and defer (not transmit because the link is in use).  This will stop a complete cell and all of it's clients from talking - ever.  DCA will of course change the channel - however this could take 10 minutes.  CleanAir ED-RRM (Energy Detect RRM) allows the AP that positively identifies interference sources of this type to immediately change it's channel - and tell RRM after.  This happens in as little as 30 seconds.

 

Another example of how CleanAir helps RRM do a better job is in mitigating persistent non Wi-Fi interference.  Lets use a Microwave Oven as an example.  In an office - the Microwave will run pretty much constant through the lunch hour - and then again at around 3 PM for the popcorn crowd.  During the time the microwave operates - any AP near it will have interference (unusable) while it is in operation anywhere between channel 6 and 11 in 2.4 GHz.  RRM will move the AP's, however once the Microwave has stopped - it is quite likely that the best channel was in the path of that Microwave oven - and the whole thing will repeat the next day.  Persistent Device Mitigation will allow the AP to remember that the microwave is there, this is communicated to RRM and a Bias is put against the affected channels - for that AP alone.  DCA will calculate a channel plan that avoids the interference - only in the areas where it impacts your AP's.  The interference is "remembered" by the AP for 7 days.  If it is never detected again - it clears, but it also refreshes for another 7 days each time it is detected.

 

https://www.cisco.com/c/en/us/solutions/collateral/enterprise-networks/cleanair-technology/white_paper_c11-599260.html?dtid=osscdc000283

Thanks Jim for clarification.

thanks, Jiflorwi. When RRM/Event RRM is starting to work does it affect on client connections at that moment?. I mean it causes the client disruption? 

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