Since updating to 10134 we’ve seen some odd behavior out of our high interface utilization alerts.

The alert itself is very simple, device matches *, entity is ifType equals ethernetCsmacd, and the test conditions are any of:

ifInOctets_perc ge 80
ifOutOctets_perc ge 80

Which has worked fine forever.

Now it’s throwing alarms on an odd mix of devices (UBNT, Palo Alto, Arista, Kemp VLM, Infoblox) for ports that are down/down loopbacks or HA interfaces not connected.

All of the ports it is alarming on show this in the data (Speed 0, and down/down):

ifSpeed=>0

ifHighSpeed=>0

ifOperStatus=>down

ifAdminStatus=>down

Any idea what changed or why it’s alarming on these now? I’m guessing its trying to do the 80% math on….0 but I’d imagine that shouldn’t even run if the port is admin+operationally down.

This is a mgmt interface on an arista (which is unconnected and admin down):

https://pastebin.com/JsNvre40

As you can see the *_perc calcs are 0, it almost seems some kind of divide by 0 error.

Thanks in advance!

Spencer Ryan | Senior Systems Administrator | spencer.ryan@netscout.com

Arbor Networks | The security division of NETSCOUT

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