User Manual

User Manual rev. 1.0. Feb. 2016

2-4.3 Relay

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

condition, please make sure the switch configuration of VLAN interface IP address

and PVID(Port VLAN ID) correctly.

Web Interface

To configure DHCP Relay in the web interface:

1. Click Configuration, DHCP, Relay

2. Specify the Relay Mode, Relay server, Relay Information Mode, Relay

Information police.

3. Click Apply.

Figure 2-4.3: The DHCP Relay Configuration

Parameter description:

 Relay Mode :

Indicates the DHCP relay mode operation.

Possible modes are:

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: 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 equal 0, in stackable device it means switch ID), and

the last two characters are the port number. For example, "00030108" means the