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manishsr1
Beginner

what is difference between cisco clean air and DCA

what is difference between cisco clean air and DCA ?

5 REPLIES 5
Leo Laohoo
VIP Community Legend

CleanAir is a unique feature that detects and classifies wireless interference.  

 

DCA means Dynamic Channel Assignment.  It means that the WLC will detect Wi-Fi related channel interference and make changes accordingly.

what i believe is Cisco clean air is silicon level feature, which is device based but DCA is taken care by WLC through   RRM .

Abhishek Abhishek
Cisco Employee

Cisco® CleanAir™ technology uses silicon-level intelligence to create a spectrum-aware, self-healing, and self-optimizing wireless network that mitigates the impact of wireless interference and offers performance protection for 802.11n and 802.11ac networks.

With CleanAir the RRM DCA algorithm can detect, measure, register and remember the impact and adjust the DCA algorithm. This minimizes the use of channels affected by the persistent devices in the channel plan local to the interference source. Cisco CleanAir detects and stores the persistent device information in the Cisco WLC and this information is used to mitigate interfering channels.

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

jkilleda
Participant

Hello Manish,


what is difference between cisco clean air and DCA

Dynamic channel assignment -DCA

Dynamically manages channel assignment for an RF group.

DCA's job is to monitor the available channels for the RF group and track the changing conditions.

Cisco clean Air

Cisco's CleanAir system integrates spectrum analysis into wireless access points to provide real-time, always-on visibility into external non-Wi-Fi sources of interference present in the environment.
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