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
(Optional) Enables UDLD in aggressive mode on the specified interface.
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
Modification
Release
This command was introduced.
Cisco IOS XE 3.2SE
Usage Guidelines
A UDLD-capable port cannot detect a unidirectional link if it is connected to a UDLD-incapable port of
another controller.
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.
Layer 2/3 Command Reference, Cisco IOS XE Release 3E (Cisco WLC 5700 Series)
70
OL-32323-01
Layer 2/3 Commands
udld port