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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 22 Configuring IP Unicast Routing
Configuring IP Addressing
Beginning in privileged EXEC mode, follow these steps to use the bridging spanning-tree database to
flood UDP datagrams:
Use the no ip forward-protocol spanning-tree global configuration command to disable the flooding
of IP broadcasts.
In the Catalyst 3550 switch, the majority of packets are forwarded in hardware; most packets do not go
through the switch CPU. For those packets that do go to the CPU, you can speed up spanning tree-based
UDP flooding by a factor of about four to five times by using turbo-flooding. This feature is supported
over Ethernet interfaces configured for ARP encapsulation.
Beginning in privileged EXEC mode, follow these steps to increase spanning-tree-based flooding:
To disable this feature, use the no ip forward-protocol turbo-flood global configuration command.
Monitoring and Maintaining IP Addressing
When the contents of a particular cache, table, or database have become or are suspected to be invalid,
you can remove all its contents by using the clear privileged EXEC commands.
Table 22-3
lists the
commands for clearing contents.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
ip forward-protocol spanning-tree
Use the bridging spanning-tree database to flood UDP datagrams.
Step 3
end
Return to privileged EXEC mode.
Step 4
show running-config
Verify your entry.
Step 5
copy running-config startup-config
(Optional) Save your entry in the configuration file.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode
Step 2
ip forward-protocol turbo-flood
Use the spanning-tree database to speed up flooding of UDP
datagrams.
Step 3
end
Return to privileged EXEC mode.
Step 4
show running-config
Verify your entry.
Step 5
copy running-config startup-config
(Optional) Save your entry in the configuration file.
Table 22-3 Commands to Clear Caches, Tables, and Databases
Command
Purpose
clear arp-cache
Clear the IP ARP cache and the fast-switching cache.
clear host {name | *}
Remove one or all entries from the host name and the address cache.
clear ip route {network [mask] |*}
Remove one or more routes from the IP routing table.
