H3C Technologies H3C S7500E Series Switches - Manual (Page 66)

6-1
6
DHCP Relay Agent Configuration
When configuring the DHCP relay agent, go to these sections for information you are interested in:
z Introduction to DHCP Relay Agent
z DHCP Relay Agent Configuration Task List
z Configuring the DHCP Relay Agent
z Displaying and Maintaining DHCP Relay Agent Configuration
z DHCP Relay Agent Configuration Examples
z Troubleshooting DHCP Relay Agent Configuration
Introduction to DHCP Relay Agent
Application Environment
Since DHCP clients request IP addresses via broadcast messages, the DHCP server and clients must
be on the same subnet. Therefore, a DHCP server must be available on each subnet, which is not
practical.
DHCP relay agent solves the problem. Via a relay agent, DHCP clients communicate with a DHCP
server on another subnet to obtain configuration parameters. Thus, DHCP clients on different subnets
can contact the same DHCP server for ease of centralized management and cost reduction.
In addition to forwarding DHCP packets between a DHCP server and clients on a public network, an
MCE device serving as the DHCP relay agent can also forward DHCP packets between a DHCP
server and clients on a private network. Note that the IP address ranges of the public and private
networks or those of private networks cannot overlap each other. For details about MCE, refer to MCE
Configuration in the MPLS Configuration Guide.
Fundamentals
Figure 6-1 shows a typical application of the DHCP relay agent.