Introduction | SNMP Architecture | the Protocol
Structure of Management Information | Object Identifier
Management Information Base | Common Tasks | References

The Protocol

SNMP uses the UDP (User Datagram Protocol) to represent independently all messages sent. It means that a message arrives has no guarantee. Five type messages are defined in agent and manager communication:

• get-request - used to request a variable value from the agent
• get-next-request - used to request the next variable value
• get-response - the variable value returned from the agent
• set-request - used to set the value of a group of variables
• trap - a notify from the agent to the manager

All types of messages use UDP port 161, except the last, the trap operator, who uses UDP port 162. At the SNMPv2, two more type messages were defined:

• get-bulk-request - used to retrieve large blocks of data
• inform-request - allows manager to switch messages