Cisco Catalyst 2960 Command Reference Manual page 523

Chapter 2 Catalyst 2960 Switch Cisco IOS Commands
ports. When the switch is operating in MST mode, BPDUs are not sent on nonboundary interfaces if the
interface is blocked by loop guard in all MST instances. On a boundary interface, loop guard blocks the
interface in all MST instances.
To disable root guard or loop guard, use the spanning-tree guard none interface configuration
command. You cannot enable both root guard and loop guard at the same time.
You can override the setting of the spanning-tree loopguard default global configuration command by
using the spanning-tree guard loop interface configuration command.
Examples This example shows how to enable root guard on all the VLANs associated with the specified port:
Switch(config)# interface gigabitethernet0/2
Switch(config-if)# spanning-tree guard root
This example shows how to enable loop guard on all the VLANs associated with the specified port:
Switch(config)# interface gigabitethernet0/2
Switch(config-if)# spanning-tree guard loop
You can verify your settings by entering the show running-config privileged EXEC command.
Related Commands Command
show running-config
spanning-tree cost
spanning-tree loopguard default
spanning-tree mst cost
spanning-tree mst port-priority
spanning-tree mst root
spanning-tree port-priority
spanning-tree vlan
OL-8604-04
Description
Displays the current operating configuration. For syntax
information, select Cisco IOS Configuration Fundamentals
Command Reference, Release 12.2 > File Management
Commands > Configuration File Management Commands.
Sets the path cost for spanning-tree calculations.
Prevents alternate or root ports from becoming designated
ports because of a failure that leads to a unidirectional link.
Configures the path cost for MST calculations.
Configures an interface priority.
Configures the MST root switch priority and timers based on
the network diameter.
Configures an interface priority.
priority Sets the switch priority for the specified spanning-tree
instance.
Catalyst 2960 Switch Command Reference
spanning-tree guard
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