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=== Communication Architecture ===To get information from an SNMP device, a "manager" (SNMP terminology for a client) will send a "GetRequest" or "GetNextRequest" to an "agent" (the SNMP term for a server) and the requested information or an error message will be sent back in a "Response." If a manager wants to modify information on an agent, a "SetRequest" will be sent with a corresponding response to confirm or report an error.The unsolicited message form is called a "trap." This kind of message is usually sent by agents on start-up, on status change and in response to error conditions. Traps are not only unsolicited but they are also unreliable. Like syslog messages they are sent via User Datagram Protocol and whether they are received depends on whether they make it to the destination (remember, UDP is an unreliable, best-effort service) and whether the manager is listening.The information on the agent is stored in what is called a Management Information Base (MIB). This is a hierarchical data structure (not, as it is often mistakenly called, a database) that describes all the "objects" that a device can report the status of and, in some cases, set the value of.