Specifications

CHAPTER

12-1

Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide

78-11380-07

Configuring STP

This chapter describes how to configure the Spanning Tree Protocol (STP) on your Catalyst 2950 or

Catalyst 2955 switch.

For information about the Rapid Spanning Tree Protocol (RSTP), the Multiple Spanning Tree Protocol

(MSTP), and the per-VLAN rapid spanning tree (PVRST), see Chapter 13, “Configuring RSTP and

MSTP.” For information about optional spanning-tree features, see Chapter 14, “Configuring Optional

Spanning-Tree Features.”

Note For complete syntax and usage information for the commands used in this chapter, refer to the command

reference for this release.

This chapter consists of these sections:

• Understanding Spanning-Tree Features, page 12-1

• Configuring Spanning-Tree Features, page 12-10

• Displaying the Spanning-Tree Status, page 12-21

Understanding Spanning-Tree Features

These sections describe how spanning-tree features work:

• STP Overview, page 12-2

• Supported Spanning-Tree Instances, page 12-2

• Bridge Protocol Data Units, page 12-2

• Election of the Root Switch, page 12-3

• Bridge ID, Switch Priority, and Extended System ID, page 12-4

• Spanning-Tree Timers, page 12-5

• Creating the Spanning-Tree Topology, page 12-5

• Spanning-Tree Interface States, page 12-6

• Spanning-Tree Address Management, page 12-8

• STP and IEEE 802.1Q Trunks, page 12-8