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Netflow v9 sensor not showing any data



Hi there,

I recently tried to setup a Netflow v9 sensor for the first time, but can´t seem to get it to display anything. With Netflow tester I can confim that data is being received and can be decoded by the PRTG server, but nothing gets displayed, even after I had let it sit for two weeks now.

Sample output from Netflow tester (I replaced some part of the IP´s with x´s, in reality it shows vaild IP´s)

  • ID:260 - 10.x.x.x:0-> E:0 EE:0 P:6 IF/OF:230/0 13:16:56 -1
  • ID:260 - 10.x.x.x:0->10.x.x.x:0 E:0 EE:0 P:6 IF/OF:230/0 13:16:56 -1
  • ID:260 - 10.x.x.x:0->10.x.x.x:0 E:0 EE:0 P:17 IF/OF:230/0 13:16:56 -1
  • ID:260 - 10.x.x.x:0->10.x.x.x:0 E:0 EE:0 P:6 IF/OF:230/0 13:16:56 -1

Any guidance would be greatly appreciated.

Best regards,


netflow prtg troubleshooting

Created on May 16, 2022 12:55:53 PM

1 Reply



Hi Matthias,

Thank you for your message.

According to the results you shared, the PRTG server receives flows but we can see the value "-1" at the end. This indicates that the device is not sending bandwidth data and therefore the sensor doesn't have information to display.

​To confirm that it's the case, I invite you to follow the steps below:

  • Generate the probe state files by using the button Go! under Setup > System Administration > Administrative Tools (/systemsetup.htm?tabid=7) > Administrative Tools For Probes > Write Probe State Files.
  • Connect to the probe server (local probe or remote probe) and open the data folder (path visible in PRTG Administration Tool)
  • Within the Logs\debug folder, open the file Probe State (xFlow Debug Data) 00.txt and look for the flow collector of your sensor (if you only have one NetFlow sensor configured on the probe, you will only get one collector only).
  • When you find it, look for Flows NoTraffic. The value must be equal to 0 otherwise it indicates that the flows have no bandwidth information.

If this is the case, then there is a configuration issue on your device which exports the flows. Here are some documentations which might help about this matter: https://overlaid.net/2014/07/09/configuring-netflow-on-nexus-nxos/ https://www.nazaudy.com/index.php/12-technology/cisco/34-enable-netflow-v9-in-cisco-switches-with-prtg

If you have questions, do not hesitate.

Best regards.

Created on May 17, 2022 6:49:27 AM by  Florian Lesage [Paessler Support]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.