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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 28 Configuring UDLD
Default UDLD Configuration
Default UDLD Configuration
Table 28-1 shows the UDLD default configuration.
Configuring UDLD on the Switch
The following sections describe how to configure UDLD:
Fast UDLD Guidelines and Restrictions, page 28-4
Enabling UDLD Globally, page 28-5
Enabling UDLD on Individual Interfaces, page 28-6
Disabling UDLD on Individual Interfaces, page 28-7
Disabling UDLD on a Fiber-Optic Interface, page 28-7
Configuring a UDLD Probe Message Interval Globally, page 28-8
Resetting Disabled LAN Interfaces, page 28-8

Fast UDLD Guidelines and Restrictions

When using (or configuring) Fast UDLD, consider these guidelines and restrictions:
Fast UDLD is disabled by default.
Configure fast UDLD only on point-to-point links between network devices that support fast
UDLD.
You can configure fast UDLD in either normal or aggressive mode.
Do not enter the link debounce command on fast UDLD ports.
Configure fast UDLD on at least two links between each connected network device. This reduces
the number of link disablements due to false positives.
Fast UDLD does not report a unidirectional link if the same error occurs simultaneously on more
than one link to the same neighbor device.
Fast UDLD is supported on a limited number of ports.
Table 28-1 UDLD Default Configuration
Feature Default Status
UDLD global enable state Globally disabled.
UDLD per-interface enable state for fiber-optic media Enabled on all Ethernet fiber-optic interfaces.
UDLD per-interface enable state for twisted-pair (copper) media Disabled on all Ethernet 10/100 and 1000BASE-TX
interfaces.
Fast UDLD per-interface enable state. Disabled on all interfaces.