Spanning-Tree Bpduguard - Cisco Catalyst 2950 Command Reference Manual

Chapter 2 Cisco IOS Commands

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
disable
enable
Defaults BPDU guard is disabled.
Command Modes
Interface configuration
Command History Release
12.1(9)EA1
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
(PVST) or the multiple spanning-tree (MST) mode. The MST mode is available only if you have the
enhanced software image (EI) installed on your switch.
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.
Examples
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.
78-11381-05
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 first introduced.
Catalyst 2950 Desktop Switch Command Reference
spanning-tree bpduguard
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