Users Guide

Layer 3 Routing Commands 1484
console#config
console(config)#ip helper-address 10.1.1.1 dhcp
console(config)#ip helper-address 10.1.2.1 dhcp
To relay UDP packets received on any interface for all default ports (see
Table 6-1) to the server at 20.1.1.1, use the following commands:
console#config
console(config)#ip helper-address 20.1.1.1
Command History
Description revised in 6.3.5 release.
ip helper-address (interface configuration)
Use the ip helper-address (interface configuration) command to configure
the relay of certain UDP broadcast packets received on a specific interface. To
delete a relay entry on an interface, use the no form of this command.
Syntax
ip helper-address {server-address | discard} [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 | discard] [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 which
relayed UDP broadcast packets are sent. The server address cannot be an
IP address configured on any interface of the local router.
• discard — Matching packets should be discarded rather than relayed, even
if a global ip helper-address configuration matches the packet.
• dest-udp-port — A destination UDP port number from 1 to 65535.
• port-name — The destination UDP port may be optionally specified by its
name. Whether a port is specified by its number or its name has no effect
on behavior. The names recognized are as follows: dhcp (port 67), domain
(port 53), isakmp (port 500), mobile-ip (port 434), nameserver (port 42),