Cisco Catalyst 3750-X Command Reference

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Catalyst 3750-X and 3560-X Switch Command Reference
OL-29704-01
Chapter 2 Catalyst 3750-X and 3560-X Switch Cisco IOS Commands
udld port
udld port
Use the udld port interface configuration command on the switch stack or on a standalone switch to enable
the UniDirectional Link Detection (UDLD) on an individual interface or prevent a fiber-optic interface
from being enabled by the udld global configuration command. Use the no form of this command to
return to the udld global configuration command setting or to disable UDLD if entered for a
nonfiber-optic port.
udld port [aggressive]
no udld port [aggressive]
Syntax Description
Defaults On fiber-optic interfaces, UDLD is not enabled, not in aggressive mode, and not disabled. For this
reason, fiber-optic interfaces enable UDLD according to the state of the udld enable or udld aggressive
global configuration command.
On nonfiber-optic interfaces, UDLD is disabled.
Command Modes Interface configuration
Command History
Usage Guidelines A UDLD-capable port cannot detect a unidirectional link if it is connected to a UDLD-incapable port of
another switch.
UDLD supports two modes of operation: normal (the default) and aggressive. In normal mode, UDLD
detects unidirectional links due to misconnected interfaces on fiber-optic connections. In aggressive
mode, UDLD also detects unidirectional links due to one-way traffic on fiber-optic and twisted-pair links
and due to misconnected interfaces on fiber-optic links. For information about normal and aggressive
modes, see the “Configuring UDLD” chapter in the software configuration guide for this release.
To enable UDLD in normal mode, use the udld port interface configuration command. To enable UDLD
in aggressive mode, use the udld port aggressive interface configuration command.
Use the no udld port command on fiber-optic ports to return control of UDLD to the udld enable global
configuration command or to disable UDLD on nonfiber-optic ports.
Use the udld port aggressive command on fiber-optic ports to override the setting of the udld enable
or udld aggressive global configuration command. Use the no form on fiber-optic ports to remove this
setting and to return control of UDLD enabling to the udld global configuration command or to disable
UDLD on nonfiber-optic ports.
aggressive Enable UDLD in aggressive mode on the specified interface.
Release Modification
12.2(53)SE2 This command was introduced.

Cisco Catalyst 3750-X Specifications

General

Brand	Cisco
Model	Catalyst 3750-X
Category	Switch
Language	English