Spanning-Tree Bpduguard - Cisco Catalyst 3550 Command Reference Manual

Multilayer switch

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spanning-tree bpduguard

Use the spanning-tree bpduguard interface configuration command to put a port in the error-disabled

state when it receives a bridge protocol data unit (BPDU). Use the no form of this command to return to

the default setting.

Syntax Description

BPDU guard is disabled.

Command Modes

Interface configuration

Command History

Usage Guidelines

The BPDU guard feature provides a secure response to invalid configurations because you must

manually put the port back in service. Use the BPDU guard feature in a service-provider network to

prevent a port from being included in the spanning-tree topology.

You can enable the BPDU guard feature when the switch is operating in the per-VLAN spanning-tree

plus (PVST+), rapid-PVST+, or the multiple spanning-tree (MST) mode.

You can globally enable BPDU guard on all Port Fast-enabled ports by using the spanning-tree portfast

bpduguard default global configuration command.

You can use the spanning-tree bpduguard interface configuration command to override the setting of

the spanning-tree portfast bpduguard default global configuration command.

This example shows how to enable the BPDU guard feature on a port:

Switch(config)# interface fastethernet0/1

Switch(config-if)# spanning-tree bpduguard enable

You can verify your setting by entering the show running-config privileged EXEC command.

Catalyst 3550 Multilayer Switch Command Reference

spanning-tree bpduguard {disable | enable}

no spanning-tree bpduguard

Disable BPDU guard on the specified interface.

Enable BPDU guard on the specified interface.

Modification

This command was introduced.

Chapter 2 Catalyst 3550 Switch Cisco IOS Commands

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