D-Link DGS-3600 Series User Manual page 284

xStack DGS-3600 Series Layer 3 Gigabit Ethernet Managed Switch
NOTE: Ports that are in the Shutdown forever mode will be seen as
Discarding in Spanning Tree windows and implementations though these
ports will still be forwarding BPDUs to the Switch's CPU.
NOTE: Ports that are in Shutdown Forever mode will be seen as link down
in all windows until the user recovers these ports.
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