SNMP Messages define how SNMP Managers communicate with SNMP Agents to retrieve the desired information. SNMP uses UDP exclusively for transport, using SNMP Response messages to acknowledge receipt of other protocol messages and supply SNMP information.
The three SNMP GET messages and the SNMP Response messages are typically used when there is an SNMP Manager asks for information from the Agent. The SNMP Manager sends one of the three types of GET messages, and the Agent replies with an SNMP Response message. An Agents entire MIB can be discovered with successive GETNEXT requests or with a GETBULK request using a process called a MIB Walk.
SNMP SET messages allow managers to change something for agents.
SNMP Traps are unsolicited messages sent by SNMP Agents to their configured management station.
SNMP INFORM Messages allows two SNMP managers to exchange MIB information about agents they both manage.