Restrictions for Configuring UniDirectional Link Detection
The following are restrictions for configuring UniDirectional Link Detection (UDLD):
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A UDLD-capable port can’t detect a unidirectional link if it’s connected to a UDLD-incapable port of another device.
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When configuring the mode (normal or aggressive), make sure that the same mode is configured on both sides of the link.
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While performing a manual reload, connected switches may enter error-disabled state on interfaces with UDLD aggressive mode enabled with lower timers, as the system needs to gracefully restart, and the CPU is handling higher priority processes. To mitigate this, either increase the hello interval or shut down all active interfaces before performing a reload.
![]() Caution |
Loop guard works only on point-to-point links. We recommend that each end of the link has a directly connected device that is running STP. |