SNMP PDUs

SNMP defines five types of PDUs, namely SNMP packets, which are exchanged between the NMS and the agent.

Figure 1 shows the SNMP packets exchanged between the NMS and the agent.

Figure 1 SNMP packet exchange

The SNMP packets are described as follows:

• get-request: indicates the NMS wants to fetch one or more parameters from the MIB of the agent.

• get-next-request: indicates the NMS wants to fetch the next parameter from the MIB of the agent.

• set-request: indicates that the NMS wants to set one or more parameters in the MIB of the agent.

• get-response: returns one or more parameters. This packet is the response returned from the agent.

• trap: are sent by the agent to inform the NMS of some important events. Sending trap packets does not require the request packets from the NMS.

The first three packets are sent from the NMS to the agent whereas the last two packets are sent from the agent to the NMS.