ECS4110-28P_Management Guide

C HAPTER 45 | DHCP Commands
DHCP Relay
– 1418 –
COMMAND MODE
Interface Configuration (VLAN)
USAGE GUIDELINES
◆ DHCP relay service applies to DHCP client requests received on the
specified VLAN.
◆ This command is used to configure DHCP relay for host devices
attached to the switch. If DHCP relay service is enabled, and this switch
sees a DHCP client request, 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 a DHCP server on
another network. 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.
◆ You must specify the IP address for at least one DHCP server.
Otherwise, the switch’s DHCP relay agent will not 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, use the ip default-gateway or
ipv6 default-gateway command to specify the default router through
which this switch can reach other IP subnetworks.
◆ To start DHCP relay service, enter the ip dhcp restart relay command.
EXAMPLE
Console(config)#interface vlan 1
Console(config-if)#ip dhcp relay server 10.1.0.99
Console(config-if)#
RELATED COMMANDS
ip dhcp restart relay (1418)
ip dhcp restart relay This command enables DHCP relay for the specified VLAN. Use the no form
to disable it.
DEFAULT SETTING
Disabled
COMMAND MODE
Privileged Exec
COMMAND USAGE
This command is used to configure DHCP relay functions for host devices
attached to the switch. If DHCP relay service is enabled, and this switch
sees a DHCP request broadcast, it inserts its own IP address into the