716 IP Helper Commands
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 2/6
console(config-if-vlan6)#ip helper-address
192.168.23.1 162
console(config-if-vlan6)#ip helper-address discard
dhcp
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