Troubleshooting Stp; Spanning Tree Protocol Failure - D-Link DES-3326 User Manual

24-port NWay Ethernet Switch User's Guide

Troubleshooting STP

Spanning Tree Protocol Failure

A failure in the STA generally leads to a bridging loop. A
bridging loop in an STP environment comes from a port that
should be in the blocking state, but is forwarding packets.
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
Understanding and Troubleshooting the Spanning Tree Protocol 387