Cisco Catalyst 3550

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Catalyst 3550 Multilayer Switch Command Reference
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Chapter 2 Catalyst 3550 Switch Cisco IOS Commands
spanning-tree mode
spanning-tree mode
Use the spanning-tree mode global configuration command to enable per-VLAN spanning-tree plus
(PVST+), rapid PVST+, or multiple spanning tree (MST) on your switch. Use the no form of this
command to return to the default setting.
spanning-tree mode {mst | pvst | rapid-pvst}
no spanning-tree mode
Syntax Description
Defaults The default mode is PVST+.
Command Modes Global configuration
Command History
Usage Guidelines The switch must run all STP instances in one of these modes: PVST+, rapid PVST+, or MST. In other
words, you cannot run STP in any two modes at the same time.
When you enable the MST mode, RSTP is automatically enabled.
Caution Changing spanning-tree modes can disrupt traffic because all spanning-tree instances are stopped for the
previous mode and restarted in the new mode.
Examples This example shows to enable MST on the switch:
Switch(config)# spanning-tree mode mst
This example shows to enable rapid PVST+ on the switch:
Switch(config)# spanning-tree mode rapid-pvst
You can verify your setting by entering the show running-config privileged EXEC command.
mst Enable MST and Rapid Spanning Tree Protocol (RSTP) (based on IEEE 802.1s and
IEEE 802.1w).
pvst Enable PVST+ (based on IEEE 802.1D).
rapid-pvst Enable rapid PVST+ (based on IEEE 802.1w).
Release Modification
12.1(9)EA1 This command was introduced.
12.1(13)EA1 The rapid-pvst keyword was added.