Layer 3 Routing Commands 1452User GuidelinesEnable DHCP Relay using the ip helper enable command. The interfaceconfiguration always takes precedence over global configuration. However, ifthere is no interface configuration, then global configuration is followed. Usethe ip dhcp relay information option command to globally enable inclusionof Option 82 information in DHCP requests forwarded to a DHCP server.ExampleThe following example enables the circuit ID and remote agent ID options onVLAN 10.console(config)#interface vlan 10console(config-if-vlan10)#ip dhcp relay information option-insertip helper-address (global configuration)Use the ip helper-address (global configuration) command to configure therelay of certain UDP broadcast packets received on any interface. To delete anIP helper entry, use the no form of this command.Syntaxip 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]no 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]• server-address — The IPv4 unicast or directed broadcast address to whichrelayed UDP broadcast packets are sent. The server address cannot be anIP address configured on any interface of the local router.• dest-udp-port — A destination UDP port number from 1 to 65535. Thisparameter need not be configured for DHCP. It must be configured for allother protocols which are to be relayed.• port-name — The destination UDP port may be optionally specified by itsname. Whether a port is specified by its number or its name has no effecton behavior. The names recognized are as follows: dhcp (port 67), domain(port 53), isakmp (port 500), mobile-ip (port 434), nameserver (port 42),
