Specifications

CHAPTER

14-1

Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide

78-11380-07

Configuring Optional Spanning-Tree Features

This chapter describes how to configure optional spanning-tree features. You can configure all of these

features when your Catalyst 2950 or Catalyst 2955 switch is running the per-VLAN spanning tree

(PVST). You can only configure the noted features when your switch is running the per-VLAN rapid

spanning tree (PVRST) and the the Multiple Spanning Tree Protocol (MSTP). To use these features with

PVRST and MSTP, you must have the enhanced software image (EI) installed on your switch.

For information on configuring the Spanning Tree Protocol (STP), see Chapter 12, “Configuring STP.”

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

Protocol (MSTP), and PVRST, see Chapter 13, “Configuring RSTP and MSTP.”

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 Optional Spanning-Tree Features, page 14-1

• Configuring Optional Spanning-Tree Features, page 14-14

• Displaying the Spanning-Tree Status, page 14-21

Understanding Optional Spanning-Tree Features

These sections describe how the optional spanning-tree features work:

• Understanding Port Fast, page 14-2

• Understanding BPDU Guard, page 14-3

• Understanding BPDU Filtering, page 14-3

• Understanding UplinkFast, page 14-4

• Understanding Cross-Stack UplinkFast, page 14-5

• Understanding BackboneFast, page 14-10

• Understanding EtherChannel Guard, page 14-12

• Understanding Root Guard, page 14-12

• Understanding Loop Guard, page 14-13