Web Management Guide-R07

Table Of Contents
Chapter 19
| IP Services
Dynamic Host Configuration Protocol
– 539 –
Figure 361: Configuring DHCP L2 Relay
Configuring DHCP L3
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 362: 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.
If any of the specified DHCP server addresses are not located in the same
network segment with this switch, specify the default router through which
this switch can reach other IP subnetworks using the IP > Routing > Static
Routes (Add) page (see Configuring Static Routes” on page 502) or the IP >
IPv6 Configuration (Configure Global) page (see Configuring the IPv6 Default
Gateway” on page 482).
DHCP relay configuration will be disabled if an active DHCP server is detected
on the same network segment.
Provides IP address
compatible with switch
segment to which client
is attached
DHCP
Server
DHCP
Server
Router