Administrator Guide

Table Of Contents
Layer-2 and Layer-3 Relay Features 1177
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.
A range of VLAN routing interfaces can be specified using
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.