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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter14 Configuring UDLD Configuring UDLD
Configuring UDLD
This section describes how to configure UDLD on your switch . It con tai ns this conf igur ati on
information:
Default UDLD Configuration, page 14-3
Enabling UDLD Globally, page 14-3
Enabling UDLD on an Interface, page 14-4
Resetting an Interface Shut Down by UDLD, page 14-4

Default UDLD Configuration

Table14-1 shows the default UDLD configuration.
UDLD is not supported on ATM interfaces. A UDLD-capable interface also cannot detect a
unidirectional link if it is connected to a UDLD-incapa ble po rt of an othe r sw itch.

Enabling UDLD Globally

Beginning in privileged EXEC mode, follow these steps to enable UDLD globally on all fiber-optic
interfaces on the switch:
Table14-1 Default UDLD Configuration
Feature Default Setting
UDLD global enable state Globally disabled
UDLD per-interface enable state for fiber-optic media Disabled on all Ethernet fiber-optic interfaces
UDLD per-interface enable state for twisted-pair (copper)
media Disabled on all Ethernet 10/100 and 1000BASE-TX
interfaces
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 udld enable Enable UDLD on all fiber-optic interfaces on the switch. UDLD is
disabled by default.
This command affects fiber-optic interfaces only . Use the udld interface
configuration command to enable UDLD on other interface types. For
more information, see the Enabling UDLD on an Interface section on
page14-4.
An individual interface configuration overrides the setting of the udld
enable global configuration command.
Step3 end Return to privileged EXEC mode.
Step4 show udld Verify your entries.
Step5 copy running-config startup-config (Optional) Save your entries in the configuration file.