Full/Half Duplex Mismatch - D-Link DES-3326 User Manual

24-port NWay Ethernet Switch User's Guide
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.
388 Understanding and Troubleshooting the Spanning Tree Protocol