Thursday, November 17, 2016

Enabling Cisco CleanAir on a Cisco WLC

Cisco CleanAir, available on Cisco AP 3700, 2700 and 2600 models, have spectrum analysis capability built right in to the radio hardware. While a CleanAir AP is busy operating its normal basic service sets (BSSs) on a channel, it can also monitor RF energy on that channel, analyze the data, and report specific information about any interfering devices - all without interrupting normal WLAN operation. This is all done with the Spectrum Analysis Engine (SAgE) chipset, operating in parallel with the normal 802.11 Wi-Fi chipset in the AP. The SAgE is always on and scans through the frequency range at a high resolution once per second. The high-resolution bandwidth enables the SAgE to identify interference sources with a high degree of accuracy.

Anything that the AP receives and recognizes as an 802.11 frame is processed normally by the split MAC architecture. Other signals that cannot be demodulated according to any known modulation and coding scheme must be coming from a non-802.11 source. That signal information is processed by the spectrum analysis hardware in the AP.

The spectrum information from every AP is sent up to the corresponding wireless LAN controller (WLC), where it can be collected and processed. If an interference source is received by more than one AP, the controller can usually correlate the data and realize that a single source is involved and not several different ones. WLCs can also pass interference reports to a Mobility Services Engine (MSE) to determine an interference source's location and display it on a Prime Infrastructure map. With CleanAir, interference can be automatically detected and identified, and its source located - which should make your job easier!

Beyond that, a Cisco unified wireless network can even react to wireless interference automatically. Recall that the RRM process is responsible for working out a channel reuse plan and assigning APs to use specific channels in a band - all on a periodic basis. Event-driven RRM can react to interference immediately, without waiting for the next scheduled RRM iteration, so that an AP can be moved to a different channel to escape the interference.


Enabling CleanAir

CleanAir operates on each band independently. You can enable or disable it globally for all APs (2600, 2700 and 3700 series) on a controller (image 7.0 and above) by selecting Wireless > 802.11a/n or 802.11b/g/n > CleanAir and using the CleanAir check box. By default, CleanAir is disabled globally on a controller.

By default, APs will report the interference types listed below to their respective controller. You can change the behavior on which the AP will report an interference by selecting a type and moving it to the Interferences to Ignore or Interferences to Detect list. You can also select which types will generate an SNMP trap from the controller when they are detected. Otherwise, any types not selected will not be reported.

Tip: An AP must be configured for either local or monitor mode before it can generate CleanAir interference reports. Reporting is not possible in the Spectrum Expert Connect (SE-Connect) mode.

As interference sources are detected and classified according to interference type, the AP also measures the received signal strength indicator (RSSI) and the duty cycle of the interferer. The duty cycle is the percentage of time the source is transmitting on the channel, which indicates its persistence or how much of the airtime the interferer is consuming. The AP combines the RSSI and duty cycle into a severity index value. Severity ranges from 0 (not severe) to 100 (very severe). Interference with a high severity rating can render a channel unusable.

Interference detection reports sent to a controller include the AP name, interference type, affected channel, time stamp, severity, duty cycle, and RSSI. The controller then tries to determine whether the same interference source is involved in reports coming from multiple APs. If so, the source is uniquely identified by assigning it a cluster ID. A cluster ID is actually a pseudo-MAC address that represents the non-802.11 device with a familiar wireless identifier.

You can display a list of interference detection reports on a controller by selecting Monitor > CleanAir > 802.11a/n/ac or 802.11b/g/n > Interference Devices.


In my wireless lab, I've used a couple of iPhones with Bluetooth enabled in order to generate some noise so that my CleanAir-enabled AP (AIR-CAP2602I) could detect it. You configure CleanAir settings on each radio (a/n/ac and b/g/n) by going to Wireless > 802.11 > CleanAir > tick Enabled > Apply.


I didn't see any interfering Bluetooth device at first, so I moved (to the right) the Bluetooth Link under Trap Configurations > Trap on these types > click Apply.


Enable Event Driven Radio Resource Management (EDRRM) on each radio under Wireless > 802.11 > RRM > DCA > tick Enabled under EDRRM > Apply. You can set the threshold to Low (AQI 35), Medium (AQI 50), or High (AQI 60).




To monitor go to Monitor > Cisco CleanAir > choose a 802.11 radio (a/n/ac or b/g/n) > Interference Device or Air Quality Report.

















Below are some useful WLC CLI commands for troubleshooting CleanAir.

(Cisco Controller) >show 802.11?
802.11a        802.11b        802.11h
(Cisco Controller) >show 802.11a ?

cleanair       Display 802.11a cleanair information.
cu-metrics     Display AP channel utilization metrics
l2roam         Display 80211a l2roam information.

media-stream   Display Media Stream configurations for 802.11 5G and 2.4G band

extended       Display 802.11a/b radio extended configurations

(Cisco Controller) >show 802.11a cleanair ?

air-quality    Display 802.11a air quality information.
config         Display 802.11a cleanair configuration.
device         Display 802.11a cleanair interfering devices information.

(Cisco Controller) >show 802.11a cleanair config

Clean Air Solution............................... Enabled
Air Quality Settings:
    Air Quality Reporting........................ Enabled
    Air Quality Reporting Period (min)........... 15
    Air Quality Alarms........................... Enabled
      Air Quality Alarm Threshold................ 35
      Unclassified Interference.................. Disabled
      Unclassified Severity Threshold............ 20
Interference Device Settings:
    Interference Device Reporting................ Enabled
    Interference Device Types:
        TDD Transmitter.......................... Enabled
        Jammer................................... Enabled
        Continuous Transmitter................... Enabled
        DECT-like Phone.......................... Enabled
        Video Camera............................. Enabled
        WiFi Inverted............................ Enabled
        WiFi Invalid Channel..................... Enabled
        SuperAG.................................. Enabled
        Canopy................................... Enabled
        WiMax Mobile............................. Enabled

--More-- or (q)uit
        WiMax Fixed.............................. Enabled
    Interference Device Alarms................... Enabled
    Interference Device Types Triggering Alarms:
        TDD Transmitter.......................... Disabled
        Jammer................................... Enabled
        Continuous Transmitter................... Disabled
        DECT-like Phone.......................... Disabled
        Video Camera............................. Disabled
        WiFi Inverted............................ Enabled
        WiFi Invalid Channel..................... Enabled
        SuperAG.................................. Disabled
        Canopy................................... Disabled
        WiMax Mobile............................. Disabled
        WiMax Fixed.............................. Disabled
Additional Clean Air Settings:
    CleanAir ED-RRM State........................ Enabled
    CleanAir ED-RRM Sensitivity.................. Medium
    CleanAir ED-RRM Custom Threshold............. 50
    CleanAir Persistent Devices state............ Disabled
    CleanAir Persistent Device Propagation....... Disabled


(Cisco Controller) >show 802.11b cleanair config

Clean Air Solution............................... Enabled
Air Quality Settings:
    Air Quality Reporting........................ Enabled
    Air Quality Reporting Period (min)........... 15
    Air Quality Alarms........................... Enabled
      Air Quality Alarm Threshold................ 35
      Unclassified Interference.................. Disabled
      Unclassified Severity Threshold............ 20
Interference Device Settings:
    Interference Device Reporting................ Enabled
    Interference Device Types:
        Bluetooth Link........................... Enabled
        Microwave Oven........................... Enabled
        802.11 FH................................ Enabled
        Bluetooth Discovery...................... Enabled
        TDD Transmitter.......................... Enabled
        Jammer................................... Enabled
        Continuous Transmitter................... Enabled
        DECT-like Phone.......................... Enabled
        Video Camera............................. Enabled
        802.15.4................................. Enabled

--More-- or (q)uit
        WiFi Inverted............................ Enabled
        WiFi Invalid Channel..................... Enabled
        SuperAG.................................. Enabled
        Canopy................................... Enabled
        Microsoft Device......................... Enabled
        WiMax Mobile............................. Enabled
        WiMax Fixed.............................. Enabled
        BLE Beacon............................... Enabled
    Interference Device Alarms................... Enabled
    Interference Device Types Triggering Alarms:
        Bluetooth Link........................... Disabled
        Microwave Oven........................... Disabled
        802.11 FH................................ Disabled
        Bluetooth Discovery...................... Disabled
        TDD Transmitter.......................... Disabled
        Jammer................................... Enabled
        Continuous Transmitter................... Disabled
        DECT-like Phone.......................... Disabled
        Video Camera............................. Disabled
        802.15.4................................. Disabled
        WiFi Inverted............................ Enabled
        WiFi Invalid Channel..................... Enabled
        SuperAG.................................. Disabled

--More-- or (q)uit
        Canopy................................... Disabled
        Microsoft Device......................... Disabled
        WiMax Mobile............................. Disabled
        WiMax Fixed.............................. Disabled
        BLE Beacon............................... Disabled
Additional Clean Air Settings:
    CleanAir ED-RRM State........................ Enabled
    CleanAir ED-RRM Sensitivity.................. Medium
    CleanAir ED-RRM Custom Threshold............. 50
    CleanAir Persistent Devices state............ Disabled
    CleanAir Persistent Device Propagation....... Disabled


(Cisco Controller) >show 802.11b cleanair ?

air-quality    Display 802.11b  air quality information.
config         Display 802.11b cleanair configuration.
device         Display 802.11b cleanair interfering devices information.

(Cisco Controller) >show 802.11b cleanair air-quality

Incorrect usage. Use 'show 802.11b cleanair air-quality ?' to see valid options.

(Cisco Controller) >show 802.11b cleanair air-quality ?

<Cisco AP>     Enter Cisco AP name
summary        Display a summary of 802.11b  air quality.
worst          Display information for the 802.11b radio with the worst air quality.

(Cisco Controller) >show 802.11b cleanair air-quality summary

AQ = Air Quality
DFS = Dynamic Frequency Selection

AP Name            Channel Avg AQ Min AQ Interferers DFS
------------------ ------- ------ ------ ----------- ---
APf872.eaa6.e203   1       99     99     1

(Cisco Controller) >show 802.11b cleanair air-quality worst

AQ = Air Quality
DFS = Dynamic Frequency Selection

AP Name            Channel Avg AQ Min AQ Interferers DFS
------------------ ------- ------ ------ ----------- ---
APf872.eaa6.e203   1       99     99     1

(Cisco Controller) >show 802.11b cleanair device ?

type           Display 802.11b interference information for the given device type in 2.4 GHz.
ap             Display 802.11b interference devices information for the given AP for 2.4 GHz.

(Cisco Controller) >show 802.11b cleanair device type ?
bt-link        Display 802.11b bluetooth-link devices information.
bt-discovery   Display 802.11b bluetooth-discovery devices information.
ble-beacon     Display 802.11b BLE Beacon devices information.
mw-oven        Display 802.11b microwave oven devices information.
802.11-fh      Display 802.11b frequency-hopper devices information.
802.15.4       Display 802.11b 802.15.4 devices information.
tdd-tx         Display 802.11b tdd-transmitter devices information.
jammer         Display 802.11b jammer devices information.
cont-tx        Display 802.11b continuous-transmitter devices information.
dect-like      Display 802.11b dect-like phone devices information.
video          Display 802.11b video devices information.
802.11-inv     Display 802.11b WiFi inverted devices information.
802.11-nonstd  Display 802.11b WiFi non-standard devices information.
superag        Display 802.11b superag devices information.
canopy         Display 802.11b canopy devices information.
wimax-mobile   Display 802.11b WiMax mobile devices information.
wimax-fixed    Display 802.11b WiMax fixed devices information.
msft-xbox      Display 802.11b Proprietary Microsoft device information.

(Cisco Controller) >show 802.11b cleanair device type bt-discovery

DC    = Duty Cycle (%)
ISI = Interference Severity Index (1-Low Interference, 100-High Interference)
RSSI  = Received Signal Strength Index (dBm)
DevID = Device ID
                  * indicates cluster center device


No  ClusterID          DevID  Type           AP Name                 ISI  RSSI  DC   Channel
--- ------------------ ------ ------------- ------------------------ ---- ----- ---- ----------
1 * 03:49:80:00:00:07  0x1009 BT Discovery   APf872.eaa6.e203        7    -27   1    1


(Cisco Controller) >show 802.11b cleanair device ap ?

<Cisco AP>     Enter Cisco AP name

(Cisco Controller) >show 802.11b cleanair device ap APf872.eaa6.e203

DC    = Duty Cycle (%)
ISI   = Interference Severity Index (1-Low Interference, 100-High Interference)
RSSI  = Received Signal Strength Index (dBm)
DevID = Device ID


No  ClusterID          DevID  Type           AP Name                 ISI  RSSI  DC   Channel
--- ------------------ ------ ------------- ------------------------ ---- ----- ---- ----------
1   03:49:80:00:00:07  0x1009 BT Discovery   APf872.eaa6.e203        7    -27   1    1


(Cisco Controller) >show 802.11b cleanair air-quality summary

AQ = Air Quality
DFS = Dynamic Frequency Selection

AP Name            Channel Avg AQ Min AQ Interferers DFS
------------------ ------- ------ ------ ----------- ---
APf872.eaa6.e203   1       99     99     1


(Cisco Controller) >show 802.11b cleanair air-quality worst

AQ = Air Quality
DFS = Dynamic Frequency Selection

AP Name            Channel Avg AQ Min AQ Interferers DFS
------------------ ------- ------ ------ ----------- ---
APf872.eaa6.e203   1       99     99     1

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