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Catalyst 3560 Switch Software Configuration Guide
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Chapter 36 Configuring IP Unicast Routing
Configuring IP Addressing
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.
Establishing an IP Broadcast Address
The most popular IP broadcast address (and the default) is an address consisting of all ones
(255.255.255.255). However, the switch can be configured to generate any form of IP broadcast address.
Beginning in privileged EXEC mode, follow these steps to set the IP broadcast address on an interface:
To restore the default IP broadcast address, use the no ip broadcast-address interface configuration
command.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 interface interface-id Enter interface configuration mode, and specify the Layer 3 interface
to configure.
Step 3 ip helper-address address Enable forwarding and specify the destination address for forwarding
UDP broadcast packets, including BOOTP.
Step 4 exit Return to global configuration mode.
Step 5 ip forward-protocol {udp [port] | nd | sdns}Specify which protocols the router forwards when forwarding
broadcast packets.
Step 6 end Return to privileged EXEC mode.
Step 7 show ip interface [interface-id]
or
show running-config
Verify the configuration on the interface or all interfaces.
Step 8 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 interface interface-id Enter interface configuration mode, and specify the interface to
configure.
Step 3 ip broadcast-address ip-address Enter a broadcast address different from the default, for example
128.1.255.255.
Step 4 end Return to privileged EXEC mode.
Step 5 show ip interface [interface-id]Verify the broadcast address on the interface or all interfaces.
Step 6 copy running-config startup-config (Optional) Save your entries in the configuration file.