ECS4100 Series CLI Reference Guide-R07

Chapter 32 | DHCP Commands
DHCP Relay
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Example
Console(config)#ip dhcp relay information option vlan add 1,3,5-10
Console(config)#
DHCP Relay for IPv4
ip dhcp relay server This command specifies the DHCP server or relay server addresses to use. Use the
no form to clear all addresses.
Syntax
ip dhcp relay server address1 [address2 [address3 ...]]
no ip dhcp relay server
address - IP address of DHCP server. (Range: 1-5 addresses)
Default Setting
None
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 active DHCP server. Otherwise,
the switch’s 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, 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.