Calculated item not working - Zabbix 3.4

[lpossamai]

Hi,

I've got two VPN connections on my Cisco ASA which I would like to monitor the traffic overnight. There is a cron job that runs every morning at 2am.
The goal is to have a trigger based on that calculated item. If there hasn't been any traffic on that VPN at 2am, then triggers an alert.

I created two items:

1. It runs an external script check, that checks if the VPN has been used. This is a perl script and it's working fine, as you can check below:


Item IPSec VPN Received:

Type: External check
Key: query_lan2_lan_cisco_final.pl["public","192.168.9.254","ASA","get","RX","201.201.201.201"]")
Units: bps
Update interval: 1m

Item IPSec VPN Sent:

Type: External check
Key: query_lan2_lan_cisco_final.pl["public","192.168.9.254","ASA","get","TX","201.201.201.201"]")
Units: bps
Update interval: 1m

Item vpn_calculated:

Type: Calculated
key: vpn_calculated
Formula: last("query_lan2_lan_cisco_final.pl[\"public\",\"192.168.9.254\",\"ASA\",\"get\",\"TX\",\"201.201.201.201\"]")+last("query_lan2_lan_cisco_final.pl[\"public\",\"192.168.9.254\",\"ASA\",\"get\",\"RX\",\"201.201.201.201\"]")
Units: bps
Update interval: 0
Custom intervals Scheduling = wd1-5h02-03

The latest data for that item is 0:


So that calculated item is not working. Why is that? Is that because the VPN cron job isn't running at 2am o'clock? but it is running at 2:01am as we can check the first screenshot?
How could I get this working?

Cheers!


EDIT 1 2018-07-23:
I've increased the log_level to debug mode so I can get more data (I changed the scheduling time to now for testing)

The log entries I have are:

32424:20180723:114000.384 calcitem_parse_expression() functionid:1 function:'Cisco_ASA_1:query_lan2_lan_cisco_final.pl["public","192.168.9.254","ASA","get","TX","201.201.201.201"].last()'
32424:20180723:114000.384 calcitem_parse_expression() functionid:2 function:'Cisco_ASA_1:query_lan2_lan_cisco_final.pl["public","192.168.9.254","ASA","get","RX","201.201.201.201"].last()'
32424:20180723:114000.384 In evaluate_function() function:'Cisco_ASA_1:query_lan2_lan_cisco_final.pl["public","192.168.9.254","ASA","get","TX","201.201.201.201"].last()'
32424:20180723:114000.384 In evaluate_function() function:'Cisco_ASA_1:query_lan2_lan_cisco_final.pl["public","192.168.9.254","ASA","get","RX","201.201.201.201"].last()'
32418:20180723:114000.522 In evaluate_function() function:'Cisco_ASA_1:item_calculated.last(0)'

However, the values are still 0, even though there is traffic over that VPN connection. I believe the calculated item formula is wrong due I am using an external check on this case, rather than an item.



EDIT 2:
I generated some heavy traffic over that vpn (usually the usage of it is around 10 bps. Only at a certain time of the day that it gets hard usage). Then I changed the calculated_item scheduled interval to every 5 minutes to test.

I was then able to get a value for it:


However, when I put the scheduled time back to being weekdays at 2an (wd1-5h02) I am getting value = 0 and the alert is triggered.
But at 2 am I also don't get any values... it shows me 0. Even though there has been some.

Still don't know how to fix this.

[lpossamai]

Does anyone have any tips here? I am still struggling to find a solution to this.

[trikke76]

difficult to say i would check the raw values from both items first to see what you are trying to calculate together check if you not try to count floats together in a calculated item by using numeric