D-Link DES-3326S manual Understanding Troubleshooting Spanning Tree Protocol, 319

DES-3326S Layer 3 Fast Ethernet Switch User’s Guide

B

UNDERSTANDING AND

TROUBLESHOOTING THE

SPANNING TREE

PROTOCOL

When the spanning-tree algorithm determines a port should be transitioned to the forwarding state, the following occurs:

•The port is put into the listening state where it receives BPDUs and passes them to the switch’s CPU. BPDU packets from the CPU are processed. If no BPDUs that suggest the port should go to the blocking state are received:

•The port waits for the expiration of the forward delay timer. It then moves to the learning state.

•In the learning state, the port learns station location information from the source address of packets and adds this information to its forwarding database.

•The expiration of forwarding delay timer moves the port to the forwarding state, where both learning and forwarding are enabled. At this point, packets are forwarded by the port.

Understanding and Troubleshooting the Spanning Tree Protocol 319