Users Guide

Layer 3 Routing Commands 1486
This command takes precedence over an ip helper-address command given in
global configuration mode. With the following configuration, the relay agent
relays DHCP packets received on any interface other than VLAN 5 and VLAN
6 to 192.168.40.1, relays DHCP and DNS packets received on VLAN 5 to
192.168.40.2, relays SNMP traps (port 162) received on interface VLAN 6 to
192.168.23.1, and drops DHCP packets received on VLAN 6:
console#config
console(config)#ip helper-address 192.168.40.1 dhcp
console(config)#interface vlan 5
console(config-if-vlan5)#ip helper-address 192.168.40.2 dhcp
console(config-if-vlan5)#ip helper-address 192.168.40.2 domain
console(config-if-vlan5)#exit
console(config)#interface vlan 6
console(config-if-vlan6)#ip helper-address 192.168.23.1 162
console(config-if-vlan6)#ip helper-address discard dhcp
Command History
Description revised in 6.3.5 release.
ip helper enable
Use the ip helper enable command to enable relay of UDP packets. To
disable relay of all UDP packets, use the “no” form of this command.
Syntax
ip helper enable
no ip helper enable
Default Configuration
IP helper is enabled by default.
Command Mode
Global Configuration mode
User Guidelines
This command can be used to temporarily disable IP helper without deleting
all IP helper addresses.