H3C Technologies H3C S12500-X Series Switches - Manual (Page 69)

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The DHCP relay agent and server are on different subnets, so configure static or dynamic routing to make
them reachable to each other.
Perform the configuration on the DHCP server to guarantee the client-server communication. For DHCP
server configuration information, see " DHCP server configuration examples ."
Figure 22 Network diagram
Configuration procedure
# Specify IP addresses for the interfaces. (Details not shown.)
# Enable DHCP.
system-view
[SwitchA] dhcp enable
# Enable the DHCP relay agent on VLAN-interface 10.
[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] dhcp select relay
# Specify the IP address of the DHCP server on the relay agent.
[SwitchA-Vlan-interface10] dhcp relay server-address 10.1.1.1
Verifying the configuration
After the preceding configuration is complete, DHCP clients can obtain IP addresses and other network
parameters from the DHCP server through the DHCP relay agent. You can use the display dhcp relay
statistics command to display the statistics of DHCP packets forwarded by the DHCP relay agent. If you
enable relay entry record on the DHCP relay agent with the dhcp relay client-information record
command, you can use the display dhcp relay client-information command to display relay entries.
Option 82 configuration example
Network requirements
As shown in Figure 22 , the DHCP relay agent (Switch A) replaces Option 82 in DHCP requests before
forwarding them to the DHCP server (Switch B).
• The Circuit ID sub-option is company001.
• The Remote ID sub-option is device001.
To use Option 82, you must also enable the DHCP server to handle Option 82.
Switch B
DHCP server
Switch A
DHCP relay agent
DHCP client DHCP client
DHCP client DHCP client
Vlan-int20
10.1.1.2/24 Vlan-int10
10.10.1.1/24
Vlan-int20
10.1.1.1/24