D-Link DGS-3612G - xStack Switch Reference Manual page 361

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xStack DGS-3600 Series Layer 3 Managed Gigabit Ethernet Switch
NOTE: Traffic Control cannot be implemented on ports that are set for
Link Aggregation (Port Trunking).
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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