Udld - Cisco Catalyst 2960 Command Reference Manual

udld

udld
Use the udld global configuration command to enable aggressive or normal mode in the UniDirectional
Link Detection (UDLD) and to set the configurable message timer time. Use the no form of the
command to disable aggressive or normal mode UDLD on all fiber-optic ports.
Syntax Description
aggressive
enable
message time
message-timer-interval
Defaults UDLD is disabled on all interfaces.
The message timer is set at 60 seconds.
Command Modes
Global configuration
Command History Release
12.2(25)FX
Usage Guidelines
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 "Understanding UDLD" section in the software configuration guide for this
release.
If you change the message time between probe packets, you are making a trade-off between the detection
speed and the CPU load. By decreasing the time, you can make the detection-response faster but increase
the load on the CPU.
This command affects fiber-optic interfaces only. Use the udld interface configuration command to
enable UDLD on other interface types.
You can use these commands to reset an interface shut down by UDLD:
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Catalyst 2960 Switch Command Reference
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udld {aggressive | enable | message time message-timer-interval}
no udld {aggressive | enable | message}
Enable UDLD in aggressive mode on all fiber-optic interfaces.
Enable UDLD in normal mode on all fiber-optic interfaces.
Configure the period of time between UDLD probe messages on ports that
are in the advertisement phase and are determined to be bidirectional. The
range is 7 to 90 seconds.
Modification
This command was introduced.
The udld reset privileged EXEC command to reset all interfaces shut down by UDLD
The shutdown and no shutdown interface configuration commands
The no udld enable global configuration command followed by the udld {aggressive | enable}
global configuration command to re-enable UDLD globally
Chapter 2 Catalyst 2960 Switch Cisco IOS Commands
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