Specifications

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Catalyst 4500 Se ries S wit ch C is co IO S C om mand R efer ence —Re lease I OS XE 3 .3.0 XO(1 5.1 (1)XO)
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Chapter 2 Cisco IOS Commands for the Catalyst 4500 Series Switches
udld (interface configuration mode)
udld (interfac e configurat ion mode)
To enable UDLD and Fast UDLD on an individual interface or to prevent a fiber-optic interface from
being enabled by the udld (global conf iguration mode) comma nd, use the udld interface level command.
Use the no form of this command to disable UDLD, or to return a nonfiber port to the setting specified
with the udld (global configuration mode) c ommand.
udld port {aggressive | disable}
no udld port {aggressive | disable}
udld fast-hello interval
no udld fast-hello
Syntax Description
Defaults The fiber-optic interfaces are enabled with the state of the global udld (enable or aggressive) command.
The nonfiber interfaces are enable d with UDLD disabled.
Fast UDLD is disabled.
Command Modes Interface configuration
Usage Guidelines If you enable aggressive mode, once a ll the switch port’s neighbor s have aged out either in the
advertisement or in the detection phase, UDLD and Fast UDLD restart the linkup sequence. They can
resynchronize with any potentially out- of-sync neighbor and shut down the port if the UDLD messages
from the neighbor indicate that the link state is still undetermined
Use the udld port aggressive command on fiber-optic ports to override the setting of the global udld (enable
or aggressive) command. Use the no form of the command on fiber-optic ports to restore the UDLD state as
configured by the global udld command.
If udld enable is configured globally, UDLD is enabled on all fiber-optic interfaces in
nonaggressive mode. You can configure udld port aggressive o n a fiber-optic interface to override
the udld enable command setting and to enter aggressive mode. If you enter the
no udld port aggresive command, the se ttings of the previous global state are reestablished and the
aggressive mode is removed.
The disa ble keyword is suppor ted on fiber-optic ports onl y. Use the no form of the udld command to
reset UDLD to the value specified by the udld (global configuration mode) command.
If the port changes from fiber-optic to nonfiber-optic or vice versa, all configurations are maintained.
aggressive Enables UDLD in aggressive mode.
disable Disables UDLD.
fast-hello Enables Fast UDLD with the configured timer.
interval Sets the timer interval.