Flow collector - flow sources

A list of the detected NetFlow sources appears automatically on the Flow Sources screen in the NAM Probe configuration settings of the NAM Console. You can subsequently edit settings for individual NetFlow sources to modify the SNMP community name and SNMP port if the device status indicates an error.

To access the table of the detected NetFlow sources and modify individual source settings:

  1. Review the information and settings for the displayed NetFlow sources.

    The status of the devices can assume the following values:

    OK

    The SNMP connection is working as configured.

    Error

    There is an SNMP connection error due to, for example, an incorrect community string or port number.

    None

    No status information has been received for this device since the device settings were last modified.

    When a configuration change is made to specific NetFlow source settings (community name or port number), time is needed to obtain a new device status based on the new settings. This time delay should take about one monitoring interval, but could take up to two intervals, depending on where in the monitoring cycle the configuration change occurred. During this time, a None status is reported.

    N/A

    The SNMP status not available for this outdated entry.

    Normally entries that have stopped communicating are automatically deleted from the status table. However, entries containing custom address or port numbers are retained for future reference but with a status of N/A .

    More detailed information for the selected row of the Devices table is displayed immediately below the table. In particular, the following information can be used for troubleshooting purposes:

    Last failed SNMP connection

    The time and date of the last failed connection with the device.

    This is useful if you are troubleshooting. If the last failed connection is a couple of minutes ago, you know this issue is current.

    Last flow received

    The time and date of the last flow received from the device.

    This shows you which devices may no longer be sending NetFlows. When they reach an inactivity time, they are automatically purged from the list. However, if they are reactivated, they will appear back on the list automatically.

  2. Modify settings for problem entries.
    To correct SNMP settings for problem entries, modify the community name or port number as required.

  3. Specify WAN interface names, if required.

    The WAN Interface configuration setting allows you to specify network interfaces for expected WAN optimization which allows the NAM Probe to determine whether traffic compression occurs during the optimization.

  4. Configure RTT-related settings, if required.
    For NetFlow version 9 it is possible to configure the NetFlow collector to retrieve and interpret client RTT.

    1. Configure RTT template value.
      The value entered is this field allows the analyzer to identify which field carries the RTT information. This value is vendor-specific and it should not be regarded as a simple field number. This feature has been tested for Riverbed with the value of 110 and for Cisco with the value of 42074 .
    2. Configure RTT measurement type.
      The value in the field specifies how to interpret the RTT information received from the NetFlow device. For example, single measurements vs. cumulative measurements. Note that this is vendor-specific and should not be regarded as a simple factor to divide the metric by. For tested Riverbed equipment this parameter was not used (enter 0), for Cisco enter 42060.
  5. Publish the draft configuration on the monitoring device.

  6. Wait and re-examine the updated status information.
    After you publish the configuration, you will have to wait up to two monitoring intervals for the displayed status of the modified entries to be updated. During that time the status will appear as None.

    After waiting of maximum two monitoring intervals, the status information will be updated for the entries for which configuration was modified.

  7. If problems persist, repeat Step 2 to Step 6 until all problems have been resolved.