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How to set a appropriate Scanning Interval for Netflow sensor?



I have some questions about NetFlow sensor.

1) Should a scanning interval for NetFlow sensor be set shorter than Active Flow Timeout? When setting the Scanning Interval, is it not necessary to consider Active Flow Timeout?

2) There is a sentence below in the manual. "We recommend that you set the timeout one minute longer than the respective timeout configured in your hardware router device. The maximum timeout is 60 minutes."

Why do you recommend about one minute?

active-flow-timeout netflow netflow-v9 scanning-interval

Created on Feb 23, 2021 8:08:16 AM

3 Replies



Hello Jonathan,

Regarding your question please take a look below:

  1. I would recommend to take a look here about more detailed information about Active Flow Timeout.
  2. That is a general recommendation. If you set this value too low, flow information might be lost.

Kind regards

Felix Wiesneth - Team Tech Support

Created on Feb 23, 2021 3:24:16 PM by  Felix Wiesneth [Paessler Support]



Hi, Felix Wiesneth

The KB post you mentioned was helpful.

But I still have a few questions about Netflow sensor.

As I know that Netflow is a UDP protocol that exports data by push method. Does PRTG collect Netflow data by polling method every scanning interval?

Or is it to continuously receive all NetFlow data regardless of the scanning interval, and then generate statistics at each scanning interval?

If the NetFlow sensor waits for flow data for Active Flow Timeout value, Is it retroactively added to the live data in real time?

Thanks in advance.

Created on Feb 28, 2021 11:45:59 PM

Last change on Mar 2, 2021 7:02:46 AM by  Felix Wiesneth [Paessler Support]



Hi Jonathan,

Netflow will not be polled. NetFlow is received from the device. PRTG generate the statistics every scanning interval.

Kind regards

Felix Wiesneth - Team Tech Support

Created on Mar 5, 2021 7:59:01 AM by  Felix Wiesneth [Paessler Support]

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