Cisco Systems 3750E Monitoring and Maintaining IP Addressing, Clear arp-cache, Clear host name

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:

	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.

Use the no ip forward-protocolspanning-treeglobal 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:

	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.

To disable this feature, use the no ip forward-protocolturbo-floodglobal 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 38-2lists the commands for clearing contents.

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.

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 38-3lists the privileged EXEC commands for displaying IP statistics.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
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