Here are some various free tools/software to help you monitor and debug your devices using SNMP:
- With this tool you can run simple SNMP requests against a device in your network in order to find communication and/or data problems in SNMP monitoring configurations.
- Download / Usage Instructions
- Wireshark allows us to analyze network packets using different protocols (by monitoring different ports). Monitoring the 161 and 162 UDP ports allows us to read SNMP network packets.
- Download / WireShark Wiki on SNMP