Troubleshooting Tip: SNMP sensor or probe showing as down

[emalayan]

Description	This article describes how to handle an issue where SNMP monitoring sensors show as down, show as having incorrect data, or show no data on either the SNMP sensors or probe.
Scope	FortiGate.
Solution	Some OIDs that are typically used (such as memory usage, CPU usage, session count, and uptime) do not change: those are the OIDs that are pre-configured on any monitoring tool such as PRTG, Solarwinds, Zabbix, etc. However, due to differences in interfaces and features on different FortiGate models, some OIDs vary. OIDs can also change after firmware upgrade. When upgrading firmware, update the corresponding OID for the SNMP sensors and probes to match the new version for proper functionality. To find correct or updated OID values after firmware upgrade, download the MIB files from the Fortigate on the GUI by going to System -> SNMP and using an MIB reader application such as PRTG MIB reader to extract OID libraries from MIB files. If the issue persists, refer to Troubleshooting SNMP query failure from the SNMP manager to the firewall. Related links for SNMP OID: FortiGate Guide for MIB