A network management station (NMS) is software that centrally monitors and manages network devices through SNMP. It can collect status and performance data, trigger alerts, and modify device configurations without requiring separate CLI logins. section 6.0 section 6.1
An NMS participates in SNMP operations through these components and message flows:
- Runs an SNMP manager, which sends Get and Set messages to agents on managed devices. section 6.1.1 section 6.1.2
- Uses an SNMP application, commonly with a GUI, so an administrator can control monitoring and management tasks. section 6.1.2
- Queries variables in a managed device’s Management Information Base (MIB), such as interface status, CPU utilization, temperature, or routing-neighbor state. section 6.1 section 6.4
- Receives Response messages and unsolicited Trap messages when managed devices report events such as an interface going down. section 6.1.1 section 6.1.2
- Uses UDP port 161 for agent-side message handling and UDP port 162 for manager-side message handling. section 6.1.2
Read-only and read-write access
A Cisco device can distinguish monitoring from configuration authority with community strings: `snmp-server community password123 RO` permits reads, while `snmp-server community password456 RW` permits reads and Set operations. Trap delivery additionally requires `snmp-server enable traps` and an `snmp-server host` command identifying the NMS. section 6.3.1
