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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02
Chapter 38 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 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 38-2 lists the
commands for clearing contents.
You can display specific statistics, such as the contents of IP routing tables, caches, and databases; the
reachability of nodes; and the routing path that packets are taking through the network. Table 38-3 lists
the privileged EXEC commands for displaying IP statistics.
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 38-2 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 hostname and the address cache.
clear ip route {network [mask] |*} Remove one or more routes from the IP routing table.