Before you can view meaningful reports, you must configure Flow Monitor and Flow-enabled devices, such as routers or switches, to communicate network activity back to the Flow Monitor listener application.
Configuring Flow sources is a three-part process that requires:
To configure Flow Monitor to listen for NetFlow data:
Note: By default, Flow Monitor listens for Flow data on port 9999. If you want to use that port, you do not need to perform this procedure.
To configure Flow devices to send Flow data to Flow Monitor: Caution: This procedure is an example that applies to a Cisco 1812 router and should not be used for other devices. The process for configuring a device to export Flow data varies widely from device to device and dependent upon your network configuration. Please see your router's documentation to determine the correct process for your device.
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Enters privileged EXEC mode. Enter your password if prompted. |
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Enters configuration mode. |
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Sets the version of the NetFlow protocol that should be used to export data. Flow Monitor supports versions 1, 5, and 9 only. |
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Enables the router to export Flow data. Substitute the Flow Monitor server's IP address for <IP> and the listener port specified in the Flow Monitor Flow Settings dialog for <port>. |
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Command |
Purpose |
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Enters the configuration mode for the interface you specify. Substitute <interface> with the interface's name on the router. |
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Enables Flow data export. Select the command that best fits your needs.
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Tip: If the device exporting Flow data is also performing network address translation (NAT), we recommend exporting egress data from the internal interface so that private network addresses are communicated. Any other configuration results in all private addresses reporting as the public addresses of the device performing the network address translation.
Note: Other options exist for configuring NetFlow. For a complete list of available options, see Configuring NetFlow on the Cisco Web site.
To configure options for Flow sources in Flow Monitor:
Note: If you cannot locate a source in the list, verify that the source device is set up to export Flow data properly. All devices sending Flow data to Flow Monitor automatically appear in the list.
Note: Null(0) interface names are hidden by default because they are not a true source interface. Null(0) interfaces show traffic that a router has dropped or traffic that a router has generated. In both cases the ifIndex = 0 and as a default convention we name an interface = Null because the interface is none existent. If you want Null(0) interface information to display as a source interface, make sure that you uncheck the Hide this interface from the Flow Monitor Home page and related configuration properties option.
After you configure the listener port and set up Flow Monitor sources, Flow Monitor begins tracking data and generating reports.