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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter22 Configuring IP Unicast Routing Configuring IP Addressing
If you do not specify any UDP ports when you configure the forw ard in g of U DP br oa dcast s, you a r e
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:
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.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Enter interface configuration mode, and specify the Layer 3 interface
to configure.
Step3 ip helper-address address Enable forwarding and specify the destination addres s for forwardi ng
UDP broadcast packets, including BOOTP.
Step4 exit Return to global configuration mode.
Step5 ip forward-protocol {udp [port] | nd | sdns} Specify which protocols the router forwards when forwarding
broadcast packets.
udpForward UDP datagrams.
port: (Optional) Destination port that controls which UDP
services are forwarded.
ndForward ND datagrams.
sdnsForward SDNS datagrams
Step6 end Return to privileged EXEC mode.
Step7 show ip interface [interface-id]
or
show running-config
Verify the configuration on the interface or all interfaces.
Step8 copy running-config startup-config (Optional) Save your entries in the configuration file.