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