162 
 
Figure 10-16 DHCP Relay Application 
To allow all clients in different VLAN request IP address from one server successfully, the DHCP 
Relay function can transmit the DHCP packet between clients and server in different VLANs, and 
all clients in different VLANs can share one DHCP Server.   
  When receiving DHCP-DISCOVER and DHCP-REQUEST packets, the switch will fill the 
giaddr field with the interface IP of the receiving port, optionally insert the option 82 
information, and then forward the packet to the server. 
  When receiving DHCP-OFFER and DHCP-REQUEST packets from the server, the switch will 
delete the option 82 information and forward the packet to the interface which receives the 
request.   
The process will be shown as follows.   
 
Figure 10-17 DHCP Relay Process 
  DHCP Relay Configuration 
1)  Configure the Option 82 parameters to record the information of the clients. You are 
suggested to configure the option82 on the nearest Relay of the client.