Application Guide

[29]
Software User's
Manual
–
Version 3.0
Configuration > DHCP > Relay
DHCP Relay Configuration
A DHCP relay agent is used to forward and transfer DHCP messages between the clients and the
server when they are not in the same subnet domain. It stores the incoming interface IP address in the
GIADDR (Gateway IP Address) field of the DHCP packet. The DHCP server can use the value of
GIADDR field to determine the assigned subnet. For such condition, please make sure the switch
configuration of VLAN interface IP address and PVID (Port VLAN ID) correctly.
Relay Mode
Setting Description
Factory
Default
Enabled
Enable DHCP relay mode operation. When DHCP relay mode operation
is enabled, the agent forwards and transfers DHCP messages between
the clients and the server when they are not in the same subnet domain.
And the DHCP broadcast message won’t be flooded for security
considerations.
Disabled
Disabled Disable DHCP relay mode operation.
Relay Server
Setting Description
IP address Indicates the DHCP relay server IP address.
Relay Information Mode
Indicates the DHCP relay information mode option operation. The option 82 circuit ID format as
"[vlan_id][module_id][port_no]". The first four characters represent the VLAN ID, the fifth and sixth
characters are the module ID (in standalone device it always equals 0; in stackable device it means
switch ID), and the last two characters are the port number. For example, "00030108" means the
DHCP message receive form VLAN ID 3, switch ID 1, port No 8. And the option 82 remote ID value is
equal to the switch MAC address.