What is Simple Network Management Protocol (SNMP)

SNMP is the Simple Network Management Protocol.

The SNMP protocol is used by network management systems to communicate with network elements.
For this to work, the network element must be equipped with an SNMP agent.
Most professional-grade network hardware comes with an SNMP agent built in. These agents must be enabled and configured to communicate with the network management system.

Operating systems, such as Unix and Windows, can also be configured with SNMP agents.

SNMP Messages

SNMP messages may be initiated by either the network management system (NMS) or by the network element.
An SNMP TRAP is a message which is initiated by a network element and sent to the network management system. For example, a router could send a message if one of it's redundant power supplies fails or a printer could send an SNMP trap when it is out of paper.

An SNMP GET is a message which is initiated by the network management system when it wants to retrieve some data from a network element. For example, the network management system might query a router for the utilization on a WAN link every 5 minutes. It could then create charts and graphs from that data, or it could warn the operator when the link was overutilized.

An SNMP SET is a message which is initiated by the NMS when it wants to change data on a network element. For example, the NMS may wish to alter a static route on a router.