Operation
The DHCP server and client interact with each other in the same way regardless of whether the relay agent exists. For the interaction details, see "IP address allocation process." The following only describes steps related to the DHCP relay agent:
After receiving a DHCP-DISCOVER or DHCP-REQUEST broadcast message from a DHCP client, the DHCP relay agent fills the giaddr field of the message with its IP address and unicasts the message to the designated DHCP server.
Based on the giaddr field, the DHCP server returns an IP address and other configuration parameters in a response.
The relay agent conveys the response to the client.
Figure 21: DHCP relay agent operation
