H3C S3610-28P Operation Manual page 1006

Operation Manual – DHCP
H3C S3610&S5510 Series Ethernet Switches
DHCP client
DHCP client
Figure 3-1 DHCP relay agent application
No matter whether a relay agent exists or not, the DHCP server and client interact with
each other in a similar way (see section
following describes the forwarding process on the DHCP relay agent.
Figure 3-2 DHCP relay agent work process
As shown in the figure above, the DHCP relay agent works as follows:
1) 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 forwards the message to the designated DHCP server in
unicast mode.
2) Based on the giaddr field, the DHCP server returns an IP address and other
configuration parameters to the relay agent, which conveys them to the client.
DHCP client
DHCP relay agent
DHCP client
3-2
Chapter 3 DHCP Relay Agent Configuration
IP network
DHCP server
Dynamic IP Address Allocation Process). The