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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
78-11380-12
Chapter 10 Configuring Interface Characteristics
Configuring Ethernet Interfaces
This example shows how to turn off all flow control on a port and to display the results:
Switch# configure terminal
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# flowcontrol receive off
Switch(config-if)# flowcontrol send off
Switch(config-if)# end
Switch# show running-config
Adding a Description for an Interface
You can add a description about an interface to help you remember its function. The description appears
in the output of these commands: show configuration
, show running-config, and show interfaces.
Beginning in privileged EXEC mode, follow these steps to add a description for an interface:
Use the no description interface configuration command to delete the description.
This example shows how to add a description on a port and to verify the description:
Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface fastethernet0/4
Switch(config-if)# description Connects to Marketing
Switch(config-if)# end
Switch# show interfaces fastethernet0/4 description
Interface Status Protocol Description
Fa0/4 up down Connects to Marketing
Configuring Loopback Detection
You can use this feature to detect a loopback on a 10/100 interface at the physical layer. If you configure
the down-when-looped interface command, the system checks if the link-up is due to a loopback
condition at the physical layer. If the link-up is due to a loopback condition, the system does not let the
Ethernet link come up. The system can detect the loopback only on links that are directly connected to
that interface and not on links that are indirectly connected. The loopback detection works when the
interfaces are configured to autonegotiate.
For complete syntax and usage information for the down-when-looped interface command, see the
Cisco IOS Interface Command Reference, Release 12.1.
Command Purpose
Step 1
configure terminal Enter global configuration mode
Step 2
interface interface-id Enter interface configuration mode, and enter the interface for which
you are adding a description.
Step 3
description string Add a description (up to 240 characters) for an interface.
Step 4
end Return to privileged EXEC mode.
Step 5
show interfaces interface-id description
or
show running-config
Verify your entry.
Step 6
copy running-config startup-config (Optional) Save your entries in the configuration file.
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