Trigger goes unknown after 7 days

[choppy]

I've created a trigger which shows

Port Down HOST.GOES.HERE GigabitEthernetX/Y : servername

based on the description on the Cisco switch interface.

Up until it passed 7 days, the description was visible, but now it reads

Port Down HOST.GOES.HERE GigabitEthernetX/Y : *UNKNOWN*

The trigger hasn't changed:

Port Down {HOST.NAME} GigabitEthernetX/Y : {ITEM.VALUE1}

The trigger looks for specific words in the interface description, so it obviously is still reading the description. It's just not displaying it on the Triggers wallboard properly.

Any advice?

[choppy]

PS - Zabbix 3.4.11

[Linwood]

Any chance the interface numbers are changing? Are you using snmp-server ifindex persist ?

[Semiadmin]

Hi, choppy.
Item's History storage period is 7 days, isn't it? Triggers don't work with trends. Increase item's History storage period or use {ITEM.LASTVALUE1} instead of {ITEM.VALUE1}.

[choppy]

Thanks for the advice, Semiadmin. Can you explain (or steer me to) the difference between VALUE1 and LASTVALUE1? The description is being read from the interface once an hour and we can see that in the Item History

[Semiadmin]

The {ITEM.VALUE1} macro returns item value at the time the trigger was fired. The {ITEM.LASTVALUE1} macro returns current value.

[choppy]

I did some tests and came to the same conclusion. Thanks for the help. My trigger works now.