Cisco Catalyst 4500 Series, Software Configuration Manual

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C H A P T E R
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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
23
Configuring STP and MST
This chapter describes how to configure the Spanning Tree Protocol (STP). This chapter also describes
how to configure the IEEE 802.1s Multiple Spanning Tree (MST) protocol. MST is an IEEE standard
derived from Cisco’s proprietary Multi-Instance Spanning-Tree Protocol (MISTP) implementation. With
MST, you can map a single spanning-tree instance to several VLANs.
It includes the following major sections:
• About STP, page 23-1
•
Default STP Configuration, page 23-7
• Configuring STP, page 23-7
•
About MST, page 23-22
• MST Configuration Restrictions and Guidelines, page 23-28
•
Configuring MST, page 23-28
• About MST-to-PVST+ Interoperability (PVST+ Simulation), page 23-35
•
Configuring PVST+ Simulation, page 23-36
• About Detecting Unidirectional Link Failure, page 23-40
Note For complete syntax and usage information for the switch commands used in this chapter, see the
Cisco IOS Command Reference Guides for the Catalyst 4500 Series Switch .
If a command is not in the Cisco Catalyst 4500 Series Switch Command Reference , you can locate it in
the Cisco IOS Master Command List, All Releases .
About STP
STP is a Layer 2 link management protocol that provides path redundancy while preventing undesirable
loops in the network. For a Layer 2 Ethernet network to function properly, only one active path can exist
between any two stations. A loop-free subset of a network topology is called a spanning tree. The
operation of a spanning tree is transparent to end stations, which cannot detect whether they are
connected to a single LAN segment or a switched LAN of multiple segments.