With IPHost Network Monitor you can run simple snmp requests against a Fortinet device in your network.
fgFwPolByteCount
fg Fw Pol Byte Count
1.3.6.1.4.1.12356.101.5.1.2.1.1.3
Number of bytes in packets matching the policy. See fgFwPolPktCount.
Back to FORTINET-FORTIGATE-MIB MIB page.
IPHost Network monitor allows you to monitor fgFwPolByteCount on Fortinet device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Fortinet firewalls right now.