Web Management Guide-R04

Table Of Contents
Chapter 18
| IP Services
Dynamic Host Configuration Protocol
– 702 –
Configuring DHCP
Relay Agent Mode
Use the IP Service > DHCP > Relay page to configure the DHCP relay service mode
as either a Layer 2 Relay Agent or a Layer 3 Relay Agent.
Command Usage
If the DHCP client subnet is different from the DHCP server subnet, configure the
DHCP Relay Agent mode to L3. Otherwise, you can use the L2 option when both
the client and server are located on the same subnet.
You must specify the IP address for at least one active DHCP server. If not set,
the switch's DHCP relay agent will not be able to forward client requests to a
DHCP server.
When using L2 Relay Agent Mode, the destination server/relay agent IP
addresses and the option 82 parameters can be specified using the IP Service >
DHCP > L2 Relay.
In layer 3 mode the switch must be able to route traffic towards the servers
subnet from the DHCP client subnet. Use IP Service > DHCP > L3 Relay to
specify the DHCP server IP addresses.
If DHCP relay is enabled, and this switch sees a DHCP request broadcast, it
inserts its own IP address into the request so that the DHCP server will know
the subnet where the client is located. The switch will then forward the packet
to the DHCP server. When the server receives the DHCP request, it allocates a
free IP address for the DHCP client from its defined scope for the DHCP client's
subnet, and sends a DHCP response back to the DHCP relay agent (i.e., this
switch). This switch then broadcasts the DHCP response received from the
server to the client.
DHCP relay configuration will be disabled if an active DHCP server is detected
on the same network segment.
Parameters
These parameters are displayed:
DHCP Relay Type – L2 or L3
Web Interface
To configure a DHCP client identifier:
1. Click IP Service, DHCP, Relay.
2. Select either L2 or L3 from the drop-down menu items.
3. Click Apply.