TP-Link T3700G-28TQ User Manual page 171

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.
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.
Figure 10-16 DHCP Relay Application
Figure 10-17 DHCP Relay Process
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