With IPHost Network Monitor you can run simple snmp requests against a Fortinet device in your network.
fnSysNetworkIfNetmask2
fn Sys Network If Netmask2
1.3.6.1.4.1.12356.1.3.1.1.19
Each interface must belong to a subnet represented by netmask.
Back to FORTINET-MIB MIB page.
IPHost Network monitor allows you to monitor fnSysNetworkIfNetmask2 on Fortinet device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Fortinet switches right now.