Cisco WS-C3550-12G Software Configuration Manual page 549

Chapter 22 Configuring IP Unicast Routing
If you do not specify any UDP ports when you configure the forwarding of UDP broadcasts, you are
configuring the router to act as a BOOTP forwarding agent. BOOTP packets carry Dynamic Host
Configuration Protocol (DHCP) information.
Beginning in privileged EXEC mode, follow these steps to enable forwarding UDP broadcast packets
on an interface and specify the destination address:
Command
Step 1 configure terminal
Step 2 interface interface-id
Step 3
ip helper-address address
Step 4
exit
Step 5
ip forward-protocol {udp [port] | nd | sdns} Specify which protocols the router forwards when forwarding
Step 6
end
Step 7
show ip interface [interface-id]
or
show running-config
Step 8 copy running-config startup-config
Use the no ip helper-address interface configuration command to disable the forwarding of broadcast
packets to specific addresses. Use the no ip forward-protocol global configuration command to remove
a protocol or port.
78-11194-03
Purpose
Enter global configuration mode.
Enter interface configuration mode, and specify the Layer 3 interface
to configure.
Enable forwarding and specify the destination address for forwarding
UDP broadcast packets, including BOOTP.
Return to global configuration mode.
broadcast packets.
• udp—Forward UDP datagrams.
port: (Optional) Destination port that controls which UDP
services are forwarded.
nd—Forward ND datagrams.
•
sdns—Forward SDNS datagrams
•
Return to privileged EXEC mode.
Verify the configuration on the interface or all interfaces.
(Optional) Save your entries in the configuration file.
Catalyst 3550 Multilayer Switch Software Configuration Guide
Configuring IP Addressing
22-19