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Cisco Catalyst Blade Switch 3030 Command Reference
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Chapter 2 Cisco
Catalyst
Blade Switch 3030 Cisco IOS Commands
spanning-tree guard
Loop guard is most effective when it is configured on the entire switched network. When the switch is
operating in PVST+ or rapid-PVST+ mode, loop guard prevents alternate and root ports from becoming
designated ports, and spanning tree does not send bridge protocol data units (BPDUs) on root or alternate
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
Description
show running-config
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
.
spanning-tree cost
Sets the path cost for spanning-tree calculations.
spanning-tree loopguard default
Prevents alternate or root ports from becoming designated
ports because of a failure that leads to a unidirectional link.
spanning-tree mst cost
Configures the path cost for MST calculations.
spanning-tree mst port-priority
Configures an interface priority.
spanning-tree mst root
Configures the MST root switch priority and timers based on
the network diameter.
spanning-tree port-priority
Configures an interface priority.
spanning-tree vlan
priority
Sets the switch priority for the specified spanning-tree
instance.