Lantronix
SM12XPA Web User Guide
33848 Rev. A
Page
178
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473
Relay
Configuration
A DHCP relay agent is used to forward and to 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 field of the
DHCP packet. The DHCP server can use the value of GIADDR field to determine the assigned subnet. For such a
condition, make sure the switch configuration of VLAN interface IP address and PVID (Port VLAN ID) is correct.
To configure DHCP Relay in the web UI:
1.
Click DHCP, Relay and Configuration.
2.
Specify the Relay Mode, Relay server, Relay Information Mode, Relay Information Policy.
3.
Click Apply.
Figure 10-2.1: DHCP Relay Configuration
Parameter descriptions
:
Relay Mode
: Indicates the DHCP relay mode operation. Possible modes are:
on
: 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.
off
: Disable DHCP relay mode operation.
Relay Server
: 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), and the last two characters are the port
number. For example, "00030108" means the DHCP message received from VLAN ID 3, switch ID 1, port No 8
and the option 82 remote ID value equals the switch MAC address.
Possible modes are:
Enabled
: Enable DHCP relay information mode operation. When DHCP relay information mode
operation is enabled, the agent inserts specific information (option 82) into a DHCP message when
forwarding to DHCP server and removes it from a DHCP message when transferring to DHCP client. It
only works when DHCP relay operation mode is enabled.
Disabled
: Disable DHCP relay information mode operation.