Configuring L2 and L3 Relay Features 1107
Configuring L3 Relay (IP Helper) Settings

Beginning in Privileged EXEC mode, use the following commands to

configure switch and interface L3 DHCP relay and IP helper settings.

Command Purpose
configure Enter global configuration mode.
ip helper enable Use this command to enable the IP helper feature. It is
enabled by default.
ip helper-address

server-

address
[

dest-udp-port

|
dhcp | domain | isakmp
| mobile-ip |
nameserver | netbios-
dgm | netbios-ns | ntp |
pim-auto-rp | rip |
tacacs | tftp | time]
Configure the relay of certain UDP broadcast packets
received on any interface. Specify the one of the protocols
defined in the command or the UDP port number.
•
server-address
— The IPv4 unicast or directed broadcast
address to which relayed UDP broadcast packets are sent.
The server address cannot be an IP address configured on
any interface of the local router.
•
dest-udp-port
— A destination UDP port number from 0
to 65535.
interface vlan
vlan-id
Enter interface configuration mode for the specified
VLAN routing interface.
You can also specify a range of VLAN routing interfaces
with the interface range vlan command, for example,
interface range vlan 10,20,30 configures VLAN interfaces
10, 20, and 30.
NOTE: All VLANs must be configured as VLAN routing
interfaces.