Cisco Catalyst 3750 Metro - Udld (Interface Configuration)

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Catalyst 3750 Metro Switch Command Reference
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Chapter 2 Catalyst 3750 Metro Switch Cisco IOS Commands
udld (interface configuration)
udld (interface configuration)
Use the udld interface configuration command to enable the UniDirectional Link Detection (UDLD) on
an individual interface or prevent a fiber-optic port 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 on a nonfiber-optic port.
udld port {aggressive | disable}
no udld port {aggressive | disable}
Syntax Description
Defaults On fiber-optic ports, UDLD is not enabled, in aggressive mode, or disabled. For this reason, fiber-optic
ports enable UDLD according to the state of the udld enable or udld aggressive global configuration
command.
On nonfiber-optic ports, UDLD is disabled.
Command Modes Interface configuration
Command History
Usage Guidelines A UDLD-capable interface cannot detect a unidirectional link if it is connected to a UDLD-incapable
interface of another switch.
UDLD supports two modes of operation: normal (the default) and aggressive. In normal mode, UDLD
can detect unidirectional links due to misconnected ports on fiber-optic connections. In aggressive mode,
UDLD also can detect unidirectional links due to one-way traffic on fiber-optic and twisted-pair links
and due to misconnected ports 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.
The disable keyword is only supported on fiber-optic ports. Use the no form of this command to remove
this setting and to return control of UDLD to the udld global configuration command.
aggressive Enable UDLD in aggressive mode on the specified interface.
disable Disable UDLD on the specified interface. This keyword applies only to
fiber-optic ports.
Release Modification
12.1(14)AX This command was introduced.