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udld (global configuration mode)

Use the udld command to enable aggressive or normal mode in UDLD protocol, and to set the configurable message timer time. Use the no form of the command to:

• Disable normal mode UDLD on all fibers ports by default.

• Disable aggressive mode UDLD on all fibers ports by default.

• Disable the message timer.

Syntax Description

udld enable	Keywords to enable UDLD in normal mode by default on all fiber interfaces.
udld aggressive	Keywords to enable UDLD in aggressive mode by default on all fiber interfaces.
message time message-timer-time	Keywords to set the period of time between UDLD probe messages on ports that are in advertisement mode and are currently determined to be bidirectional; valid values are from 7 to 90 seconds.

Defaults

The default is UDLD is disabled on all fiber interfaces and the message timer is set at 60 seconds.

Command Modes

Global configuration mode.

Usage Guidelines

If you enable aggressive mode, once all the neighbors of a port have aged out either in the advertisement or in the detection phase, UDLD restarts the linkup sequence to try to get resynchronized with any potentially out-of-sync neighbor and shuts down the port if the fast train of messages the link is still undetermined.

This command affects fiber interfaces only. Use the udld (interface configuration mode) command to enable UDLD on other interface types

Examples

This example shows how to enable UDLD on all fiber interfaces:

Router (config)# udld enable
Router (config)#

Related Commands

show udld
udld (interface configuration mode)

udld (interface configuration mode)

Use the udld command to enable UDLD on an individual interface, or prevent a fiber interface from being enabled by the udld (global configuration mode) global configuration command. Use the no form of this command to return to the udld (global configuration mode) global configuration command setting, or if a non-fiber port, disable UDLD.

Syntax Description

enable	Keyword to enable UDLD on this interface; see the "Usage Guidelines" section for additional information.
aggressive	Keyword to enable UDLD in aggressive mode on this interface; see the "Usage Guidelines" section for additional information.
disable	Keyword to disable UDLD on this interface; see the "Usage Guidelines" section for additional information.

Defaults

The defaults are:

• The default for fiber interfaces is neither udld enable, udld aggressive, nor udld disable. For this reason, fiber interfaces enable UDLD as per the state of the global udld (enable or aggressive) command.

• The default for non-fiber interfaces is for UDLD to be disabled.

Command Modes

Interface configuration mode.

Usage Guidelines

If you enable aggressive mode, once all the neighbors of a port have aged out either in the advertisement or in the detection phase, UDLD restarts the linkup sequence to try to get resynchronized with any potentially out-of-sync neighbor and shuts down the port if the fast train of messages the link is still undetermined.

Use the no udld enable command on fiber ports to return control of UDLD to the global udld enable command or, in the case of non-fiber ports, disable UDLD.

Use the udld aggressive command on fiber ports to override the setting of the global udld (enable or aggressive) command. Use the no form on fiber ports to remove this setting and return control of UDLD enabling back to the global udld command or, in the case of non-fiber ports, disable UDLD.

The disable keyword is supported on fiber ports only. Use the no form of this command to remove this setting and return control of UDLD to the udld (global configuration mode) command.

If, due to a change of module or a GBIC change detected by the platform software, the port changes from fiber to non-fiber or visa versa, all configurations will be maintained.

Examples

This example shows how to cause any port interface to enable UDLD, despite the current global udld (global configuration mode) setting:

Router (config-if)# udld enable
Router (config-if)#
 

This example shows how to cause any port interface to enable UDLD in aggressive mode, despite the current global udld (enable or aggressive) setting:

Router (config-if)# udld aggressive
Router (config-if)#
 

This example shows how to cause a fiber port interface to disable UDLD, despite the current global udld (global configuration mode) setting:

Router (config-if)# udld disable
Router (config-if)#

Related Commands

show udld
udld (global configuration mode)

udld reset

Use the udld reset command to reset all ports shutdown by UDLD and permit traffic to begin passing through them again (though other features, such as spanning tree, PAGP, and DTP will still have their normal effects, if enabled).

Syntax Description

This command has no keywords or variables.

Defaults

This command has no default setting.

Command Modes

EXEC.

Usage Guidelines

If the interface configuration is still enabled for UDLD, these ports will begin to run UDLD again and may shutdown for the same reason if it has not been corrected.

Examples

This example shows how to reset all ports shutdown by UDLD:

Router# udld reset

Related Commands

show udld

Posted: Thu Jul 20 15:26:34 PDT 2000
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