How triggers work? How does it handle value changes?

[asteroidyorkton]

I'm trying to setup interface trigger that will fire if the value is above 75%.
How does trigger handle sudden change in value? Example: Traffic drop from 15Mbps to 840 kbps?
Does trigger use calculated value (after conversion of units along with custom multiplier)?

Example:
Interface current traffic=50 Mbps
Interface speed=1000 Mbps
Threshold = 75%

Item stored as Delta (speed per Second)
Item units: bps
Item multiplier: 8

Trigger
Interfaces:ifInOctets.1 * 100 / IfSpeed(100) > 75%
50 Mbps * 100 / 1000 = 5% usage

Suddenly Interface current traffic changes=840.02 kbps

Interfaces:ifInOctets.1 * 100 / IfSpeed(100) > 75%
840.02 * 100 / 1000 = 84% usage???

I can't set a trigger based on total bytes greater than (ifInOctets.1.last(0)>80M) because I have different speed interface so want a different limit and set it in a prototype.

[peatb]

You're mixing up units here.
Even though zabbix displays it in the graph as "50MBps", in the database it's stored as 5000000 (approx). So your calculation in the trigger must assume the actual stored value, not the display including the M for mega.

so look at the actual values and base your trigger on that. Then when traffic goes from 50Mbps to 800Kbps, the usage will go from 5% to 0.08%.

Since you specified your trigger at 75%, this drop will not make the trigger fire.

[asteroidyorkton]

You're mixing up units here.
Even though zabbix displays it in the graph as "50MBps", in the database it's stored as 5000000 (approx). So your calculation in the trigger must assume the actual stored value, not the display including the M for mega.

so look at the actual values and base your trigger on that. Then when traffic goes from 50Mbps to 800Kbps, the usage will go from 5% to 0.08%.

Since you specified your trigger at 75%, this drop will not make the trigger fire.

Okay i get it now.
So it should look like I should use ifInOctets / ifHighSpeed * 1024 (once or twice?)
ifHighSpeed is 1000

[peatb]

Again I'm guessing units. If I check on one of my systems:

IF-MIB::ifInOctets.2 = Counter32: 1379715791
IF-MIB::ifHighSpeed.2 = Gauge32: 1000

The highspeed is obviously not given in bits but in megabit. So you must accomodate for that in your calculation (or set a custom multiplier in the highspeed item). Make sure that the units of all components is the same and you're not dividing bits by megabits.

so ifInOctets/(ifHighSpeed*1024*1024) makes more sense.

[registration_is_lame]

Hello, What should be changed if I'm using IfHCInOctects (64 bit counters?)

Bandwidth reported is too high 400 Tbps.

Item OID - IfHCInOctects
Custom multiplier - 8
units - bps

Update: I'm guessing it happens only once - false bandwidth after changing from IfInOctects to IfHcOctects? I started seeing resolved alerts and bandwidth going down back to normal