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Monitoring RF Interference Sources on Wireless Devices


Because the 2.4-GHz band includes radio transmissions from devices other than wireless networks, interference is a common problem. Network Director detects, classifies, and displays radio interference in several monitors. This topic describes the Summary interference monitor that can be applied to various wireless objects such as a radio, an access point, a controller cluster, or an entire wireless network.


You can also monitor interference by Monitoring RF Interference Sources on One Radio and Monitoring RF Interference Sources For Radios on One Access Point.

To view a wireless object’s RF interference sources over a fixed period of time:

  1. Select Monitor Mode in the Network Director banner.
  2. Select any view from the View pane.
  3. Expand the wireless list in the View pane, then select one of the objects listed in Table 1.

    Table 1: Wireless Objects in the View Pane



    Entire Wireless Network in any view.

    Wireless Mobility Domain in any view.

    Controller Cluster in any view.

    Note: You cannot see interference for a single controller.

    Individual access point in any view.

    Individual radio in any view.

    Selecting a floor in logical view displays all access points on that floor—to create a floor, see Configuring Floors.

    Selecting a building in logical view displays all access points in that building—to create a building, see Configuring Buildings.

    Selecting a site from the logical view displays all access points in that building—to create a site, see Creating a Site.

    Wiring closet—to create a wiring closet, see Setting Up Closets.

    The Summary monitor tab becomes available when you select one of the objects listed in Table 1.

  4. Click the Summary tab.

    The RF Interference Sources Summary monitor is displayed as one of the four default monitors.

  5. Optionally, change the timeframe covered by the monitor by selecting a different time from the list.
  6. Optionally, click the monitor’s title to see a list of interfering objects along with the information listed in Table 2.

    Table 2: Information on RF Interference Sources for a Radio



    Last Seen

    Date and time the interference was last detected.

    Transmitter ID

    If the interference is caused by an object with a MAC address, the MAC address is displayed. If the object has no MAC address, MSS calculates a MAC address, using the characteristics of the object. This way, you can correlate interference events over time.

    Listener MAC

    MAC address of the access point that detected the interference.


    Name of the access point that detected the interference.


    Name of the controller that reported the interference.


    Channel the interference affected.


    Received signal strength indication (RSSI), in decibels referred to 1 milliwatt (dBm). A higher value indicates a stronger signal.

    Duty Cycle

    Reported fraction of time that the source is emitting RF.

    Source Type

    Possible sources of interference include Bluetooth, Continuous Wave, Microwave Oven, Unknown, and Phone FHSS.

    CIM (%)

    Estimated severity of interference on this channel caused by the source.

  7. Click Help (?) for information on the RF Interference Sources chart or see RF Interference Sources Monitor for Wireless Devices.

To change the polling interval for monitors, see Setting Up User and System Preferences.