In simple terms, SNMP is a protocol that's used to receive information about devices. The information received depends on what objects (and specific properties of those objects) that can be monitored on the devices. The piece of software that "sits" on the devices and collects the information is called an agent. The agent delivers, upon request, the information about the devices to the network management system.
Most networking devices are SNMP capable, which means that if you have a network management system implemented in your network, the network management system will query the agents on the devices for information. Information collected by the agents is usually information about the health of the device (i.e.: CPU usage too high, memory utilization too high, inability to ping device, etc). A network management system is basically a tool used to prevent or minimize downtime caused by device failures because the system will advise you of issues before hand.
Re: Information about SNMP
10 years 5 months ago #26947
And the other side of SNMP that many environments use is SNMP traps. Unlike the SNMP queries described by KiLLaBeE that are initiated by the management station, traps are unsolicited messages sent from the agent in the device to inform the management station of some important event. Traps can be of two types, simple event notifications (e.g. "My WAN interface has come up") or threshold notifications (e.g. "You set me up to tell you whenever utilisation on port 13 exeeded 50% - well it just has"). The latter require prior configuration while the former do not.