Sum or subtraction of items on the graph

[dimka779]

Hi. Could somebody help me with my problem.
I've got Mikrotik and I got SNMP values on ether1 port such as ifInOctets1 or ifOutOctets1 (speed per second)
I made a graph with this values.

Now I've got VLAN interface on physical ether1 (ifInOctets1) interface.VLAN SNMP values is called ifInOctets30 and ifOutOctets30.

So now I need to separate VLAN and ether1 traffic speed values.

For example:
ether1 IN speed (without VLAN traffic) = ifInOctets1 - ifInOctets30
ether1 OUT speed (without VLAN traffic) = ifOutOctets1 - ifOutOctets30
VLANspeed (without ether1 traffic) = ifInOctets30

So I created calculated item in zabbix with
last("ifInOctets.1")-last("ifInOctets.30") expression.

And then I've got error - "Cannot evaluate function [last()]: item [mymikrotik:ifInOctets.1] not found"

Thanks!

[pmariswamy]

Hi,
The function definition - last("ifInOctets.1")-last("ifInOctets.30") seems to be wrong.
I think this should be changed to,
last("ifInOctets1")-last("ifInOctets30")

PS: I am newbie so my above answer maybe wrong and the answer is just a guess based on examples at : https://www.zabbix.com/documentation...pes/calculated

- Prashanth

[aib]

Please, explain me why you use two different keys in description:
- first you are talking about key ifInOctets1
- then, in formula, you use the different key ifInOctets.1

Use in formula the same key which you have in your Item description.

ifInOctets[ether1] OR ifInOctets[1] OR ifInOctets.1

but the same key every time.

[dimka779]

Thank you all!
Now I got item values, but seems it's not correct. Because I got IN and OUT speed in petabytes/s and exabytes/s. Seems it's about conversion.

When I use just ifInOctets.1 or ifInOctets.30 in my graph I add it with this parameters:

Type of information: Numeric (float)
Units : bps
Use multiplier : Custom multiplier
Custom multiplier : 8
Store value : Delta (speed per second)

And I get correct values (kbytes,mbytes)

So now I use calculated item:
last("ifInOctets1")-last("ifInOctets30")
with same parameters:

Type of information: Numeric (float)
Units : bps
Use multiplier : Custom multiplier
Custom multiplier : 8
Store value : Delta (speed per second)

And I get not correct values in petabytes/s and exabytes/s

Now I just read SNMP values of ifInOctets1 and ifInOctets30
ifInOctets.2 = 97590243
ifInOctets30 = 554438260

But how does it possible?
ifInOctets30 it's VLAN "inside" ether2 (ifInOctets.2) and I thought that it should be less than value on ifInOctets.2 .

Thanks!