Udld Port - Cisco Catalyst 2960-X Command Reference Manual

Layer 2 Commands

udld port

To enable UniDirectional Link Detection (UDLD) on an individual interface or to prevent a fiber-optic interface
from being enabled by the udld global configuration command, use the udld port command in interface
configuration mode. To return to the udld global configuration command setting or to disable UDLD if entered
for a nonfiber-optic port, use the no form of this command.
udld port [aggressive]
no udld port [aggressive]
Syntax Description
aggressive
Command Default
On fiber-optic interfaces, UDLD is disabled and 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
Release
Cisco IOS 15.0(2)EX
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.
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.
You can use these commands to reset an interface shut down by UDLD:
• The udld reset privileged EXEC command resets all interfaces shut down by UDLD.
OL-29043 -01
(Optional) Enables UDLD in aggressive mode on the specified interface.
Modification
This command was introduced.
Catalyst 2960-X Switch Layer 2 Command Reference, Cisco IOS Release 15.0(2)EX
udld port
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