Simple Network Management Protocol definition
Simple Network Management Protocol (SNMP) is a protocol for monitoring and managing devices on a network, such as routers, switches, servers, and workstations. It lets network administrators access performance data, configure devices, and get alerts for issues.
See also: network security protocols, management information base, control plane, application layer
Simple Network Management Protocol components
- Agent. This is software that runs on network devices like routers, switches, servers, and even some modern printers and cameras. It collects and stores data about the device's operation and performance.
- Management station (or manager). This is software or device that communicates with agents to monitor and sometimes configure the network devices.
- MIB (management information base). This is essentially a database the agent uses to organize the data about the device. It uses a tree structure, each data point (or object) having a unique OID (object identifier).
How Simple Network Management Protocol works
- Polling. The management station “polls” or sends requests to the agents to get specific data. For example, it might request the current bandwidth usage on a particular router interface or the CPU usage of a server. The agent responds with the requested data.
- Traps. Unlike polling, where the manager actively requests data, traps are unsolicited messages the agent sends to the management station. Agents send traps to notify of certain events, like errors, failures, or conditions that might require attention.
- Sets. The management station can also send “set” commands to the agents to change settings on devices.
- Data structure. Information is structured hierarchically in the MIB, using OIDs. For example, an OID might represent the current status of a specific router interface or the serial number of a device. When the manager wants to retrieve or set a particular piece of information, it references the relevant OID.
SNMP uses
- Monitoring network performance. Admins use SNMP to keep an eye on network performance, availability, and responsiveness. Monitoring tools can display real-time statistics, graphs, and alerts.
- Configuration management. While SNMP is mainly known for monitoring, it also allows for some level of configuration changes to be made on devices remotely.
- Metric collection. SNMP can gather statistics like bandwidth usage, error rates, disk usage, CPU load, and memory usage from network devices.
- Fault detection. SNMP can notify network administrators of issues like device failures or connectivity problems.
- Security management. SNMP can provide information about suspicious activities or security incidents.
