NTM uses Simple Network Management Protocol (SNMP) to retrieve information about device interfaces, ARP cache, CDP data, and a variety of other statistics. SNMP queries (polls) devices for specific information, and NTM acts as an SNMP manager, polling SNMP agents installed on managed devices. The following requirement must be met for NTM to successfully poll devices:
- The device must have SNMP enabled. To enable SNMP on your devices, see the manufacturer’s documentation for the device.
- The device and NTM must share the same SNMPv2c community strings or SNMPv3 security access.
- SNMP (UDP port 161) must not be blocked between the device and NTM.
If your device fails to respond to SNMP complete the following troubleshooting steps:
- Check the device NTM credentials (SNMPv2c community string or SNMPv3 credentials) and ensure they are the same as the credentials used in NTM.
- Run a test from the NTM Add Credential interface before running discovery.
- Use a third party protocol analyzer to capture packets between NTM and the node to evaluate the issue.
The screen captures below show a successful NTM query.
SNMP Get Request
SNMP Get Response