Monitoring bandwidth traffic

[schukido]

Dear Zabbix community,

I want to monitor traffic bandwidth of the link. If its traffic decrease about 30% bandwidth in the period of time it will alarm.

For example: The bandwidth is currently around 1GB, if it decrease to 700MB >> alarm.

I config expression in Trigger like this:

(({10.90.3.243:cisco.3012.intf1.traffic.outbound.b ps.last(0)} / {10.90.3.243:cisco.3012.intf1.traffic.outbound.bps .last(180)})*100)<70

Means: last change / previous change(3minutes) *100 < 70 %

Is that expression correct ???

Thank you in advance and looking forward for your reply.

schukido