Web Management Guide-R04

Table Of Contents
Chapter 18
| IP Services
Dynamic Host Configuration Protocol
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Figure 472: Configuring the DHCP Relay Agent mode
Configuring DHCP
Layer 3 Relay Service
Use the IP Service > DHCP > L3 Relay page to configure DHCP relay service for
attached host devices. If DHCP L3 relay mode 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. Then, the switch
forwards 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 passes the DHCP response received from the
server to the client.
Figure 473: Layer 3 DHCP Relay Service
Command Usage
You must specify the IP address for at least one active DHCP server. Otherwise,
the switchs DHCP relay agent will not be able to forward client requests to a
DHCP server. Up to five DHCP servers can be specified in order of preference.
DHCP relay configuration will be disabled if an active DHCP server is detected
on the same network segment.
Parameters
These parameters are displayed:
VLAN ID – ID of configured VLAN.
Server IP Address – Addresses of DHCP servers or relay servers to be used by
the switchs DHCP relay agent in order of preference.
Restart DHCP Relay – Use this button to re-initialize DHCP relay service.
Provides IP address
compatible with switch
segment to which client
is attached
DHCP
Server
DHCP
Server
Router