SNMP (Simple Network Management Protocol) is a protocol for monitoring and managing network devices such as switches, routers, and printers. SNMP supports polling for status information and receiving automatic notifications (traps). Versions SNMPv1 and v2c transmit community strings in plain text and are considered insecure. SNMPv3 provides authentication and encryption. In your ISMS you should use SNMPv3 exclusively, change default community strings, and restrict SNMP access to management VLANs.