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DGS-3120 Series Managed Switch CLI Reference Guide 
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Chapter 27  D-Link Unidirectional Link 
Detection (DULD) Command 
List (EI Mode Only) 
 
config duld ports [<portlist> | all ] {state [enable | disable] | mode [shutdown | normal] | 
discovery_time <sec 5-65535>}(1) 
show duld ports {<portlist>} 
 
27-1  config duld ports 
Description 
The command is used to configure unidirectional link detection on ports. Unidirectional link 
detection provides discovery mechanism based on 802.3ah to discovery its neighbor. If the OAM 
discovery can complete in configured discovery time, it concludes the link is bidirectional. 
Otherwise, it starts detecting task to detect the link status. 
 
Format 
config duld ports [<portlist> | all ] {state [enable | disable] | mode [shutdown | normal] | 
discovery_time <sec 5-65535>}(1) 
 
Parameters 
<portlist> - Specify a range of ports. 
all - Specify to select all ports. 
state - Specify these ports unidirectional link detection status. 
enable - Enable unidirectional link detection status. 
disable - Disable unidirectional link detection status. 
mode - Specify the mode when detecting unidirectional link. 
shutdown - If any unidirectional link is detected, disable the port and log an event. 
normal - Only log an event when a unidirectional link is detected. 
discovery_time - Specify these ports neighbor discovery time. If OAM discovery cannot 
complete in the discovery time, the unidirectional link detection will start.  
 - Enter a time in second. The default discovery time is 5 seconds. 
 
Restrictions 
Only Administrator, Operator and Power-User level users can issue this command. 
 
Example 
To enable unidirectional link detection on port 1: