Full/Half Duplex Mismatch - D-Link DGS-3308TG User Manual

8-port Gigabit Ethernet Switch User's Guide
In this example, B has been elected as the designated bridge and port 2 on C is in the blocking state. The election of B as
the designated bridge is determined by the exchange of BPDUs between B and C. B had a better BPDU than C. B
continues sending BPDUs advertising its superiority over the other bridges on this LAN. Should C fail to receive these
BPDUs for longer than the MAX AGE (default of 20 seconds), it could start to transition its port 2 from the blocking state
to the forwarding state.
It should be noted: A port must continue to receive BPDUs advertising superior paths to remain in the blocking state.
There are a number of circumstances in which the STA can fail – mostly related to the loss of a large number of BPDUs.
These situations will cause a port in the blocking state to transition to the forwarding state.

Full/Half Duplex Mismatch

A mismatch in the duplex state of two ports is a very common configuration error for a point-to-point link. If one port is
configured as a full duplex, and the other port is left in auto-negotiation mode, the second port will end up in half-duplex
because ports configured as half- or full-duplex do not negotiate.
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