An SNMP–managed network consists of a manager, agents, and managed devices.
The manager provides the interface between the human network manager and the management system. The agent provides the interface between the manager and the physical device being managed
Management systems execute most of the management processes and provide the bulk of memory resources used for network management. A network might be managed by one or several management systems.
The figure below illustrates the relationship between the network manager, the SNMP agent, and the managed devices.
Figure 2. Example of the Primary SNMP Components
An agent residing on each managed device translates local management information data—such as performance information or event and error information—caught in software traps, into a readable form for the management system.
The figure below illustrates SNMP agent get–requests that transport data to the network management software.
Figure 3. Agent Gathering Data from a MIB and Sending Traps to the Manager
The SNMP agent captures data from MIBs, which are device parameter and network data repositories, or from error or change traps.
A managed element—such as a router, access server, switch, bridge, hub, computer host, or network element—is accessed through the SNMP agent. Managed devices collect and store management information, making it available through SNMP to other management systems having the same protocol compatibility.
It is recommended that the SNMP Manager timeout value be set to 60 seconds. Under certain conditions, if this value is lower than the recommended time, the TNC/TSC card can be reset. However, the response time depends on various parameters such as object being queried, complexity, number of hops in the node and so on.