1040 IP Helper/DHCP Relay CommandsThis command takes precedence over an ip helper-address command given inglobal configuration mode. With the following configuration, the relay agentrelays DHCP packets received on any interface other than vlan 5 and vlan 6 to192.168.40.1, relays DHCP and DNS packets received on vlan 5 to192.168.40.2, relays SNMP traps (port 162) received on interface vlan 6 to192.168.23.1, and drops DHCP packets received on vlan 6:console#configconsole(config)#ip helper-address 192.168.40.1 dhcpconsole(config)#interface vlan 5console(config-if-vlan5)#ip helper-address 192.168.40.2 dhcpconsole(config-if-vlan5)#ip helper-address 192.168.40.2 domainconsole(config-if-vlan5)#exitconsole(config)#interface 2/6console(config-if-vlan6)#ip helper-address 192.168.23.1 162console(config-if-vlan6)#ip helper-address discard dhcpip helper enableUse the ip helper enable command to enable relay of UDP packets. Todisable relay of all UDP packets, use the “no” form of this command.Syntaxip helper enableno ip helper enableDefault ConfigurationIP helper is enabled by default.Command ModeGlobal Configuration mode.User GuidelinesThis command can be used to temporarily disable IP helper without deletingall IP helper addresses.This command replaces the bootpdhcprelay enable command, but affects notonly relay of DHCP packets, but also relay of any other protocols for which anIP helper address has been configured.
