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Flapping Sensorts



At the moment we have a fairly large install of PRTG (just over 1500 sensors) and we are currently in the process of reducing 'noise' from alarms - i.e. make it so an alarm is actually an issue to be dealt with rather than something that can be ignored.

One feature that we would like to request is some way to deal with flapping sensors/devices.

We have a lot of remote sites being monitored, some of which have very flakey Internet connections or flakey VPNs. We want to know if these go down for a significant period of time, but not if they drop for just a few seconds.

Now there is the facility to increase the polling interval but this leaves it very much down to chance whether you get notified or not - i.e. if the connection happens to be down for 10s at the point when your sensor checks it will alarm.

One solution would be have an option to select 'this sensors must be down for x seconds before it alarms'.

We can already do this with ping sensors to some degree by setting the number of pings to a high number (5 second timeout and 24 pings means the device has to be down for 2mins before it warns then 2 further minutes before it alarms), but there is no way to replicate this with things like SNMP traffic sensors on the same device.

feature-request flapping sensor

Created on Mar 29, 2012 2:34:01 PM

8 Replies




this is the exact purpose of the 'Latencies' on triggers, so that notifications are only sent if a certain condition persists for a certain time. A change into the error-state of sensor in case it can't reach its target will always be immediate.

best regards.

Created on Mar 30, 2012 9:14:02 AM by  Torsten Lindner [Paessler Support]



Hi Rob,

Using the web interface, you are right. All alarms are immediately visible without the ability to use any latency.

But, using the TrayNotifier you can set a latency to only show alarms that are older than xx seconds. That way flapping sensors will not show as long as the downtime stays within the latency setting.


Created on Mar 30, 2012 7:42:25 PM



We would also like to see the ability to set 'latencies' on the sensor alarms themselves.

There are just too many different sensor types (in addition to the flapping issue) which would benefit by this simple feature. We then wouldn't have to come up with workarounds like using the traynotifier latency.

Please advise support?

Created on Feb 12, 2014 1:48:10 AM



Chris, we just talked about this internally yesterday. You could say this probably is a more 'philosophical' question, and our opinion is, that an error has to be shown immediately. We don't want to have delayed errors shown in PRTG. If PRTG detects an error, it has to show them in that very moment.
Notifications can of course be delayed with latencies, but as for the sensor state changes, we really do not want to change this fundamental principle of PRTG (and its predecessors for over a decade).

Created on Feb 12, 2014 10:32:43 AM by  Torsten Lindner [Paessler Support]



Torsten, thanks for your response. I understand and it makes sense to not change the sensor state behavior. But I still feel like something more can be done to help with the over generation of alarms.

Perhaps the sensor itself can still log/generate an error, but can we have an option to at least delay the generation of the actual alarm? This would help our NOC team since the tray notifier keeps popping up alarms that we don't need to know about right away (and setting latency on all alarms is not effective either since some we do want to know about some sensors right away).

Hope this makes sense?

Created on Feb 14, 2014 5:42:41 PM



Alarms, meaning notifications, can be delayed yes. All visual state changes will be immediate (that will include the popup of the Enterprise Console), sorry.

Created on Feb 17, 2014 10:16:15 AM by  Torsten Lindner [Paessler Support]



Dear all,

Am having a lot of headache at exactly the problem - the flapping is really killing the guys and would definitely appreciate if there is any way to "de-duplicate" the down - up - down again - up again - .... email that is being generated by devices operating in borderline conditions.

Created on Jun 11, 2017 11:15:49 AM



Dear Titus,

What is the reason for the devices being that flappy? Is it due to some unstable VPN connection between PRTG and the queried devices? In that case I would recommend deploying a remote probe near that devices to monitor them. Apart from that everything else has been discussed already before in this thread I'm afraid.

Kind regards,


Created on Jun 13, 2017 9:46:34 AM by  Erhard Mikulik [Paessler Support]

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