Cisco Catalyst 2960 Series, Configuration Manual

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Purpose Command or Action
Example:
Switch(config-if)# spanning-tree guard root
By default, root guard is disabled on all interfaces.
Returns to privileged EXEC mode. end
Example:
Switch(config-if)# end
Step 5
Related Topics
Root Guard, on page 297
Enabling Loop Guard
You can use loop guard to prevent alternate or root ports from becoming designated ports because of a failure
that leads to a unidirectional link. This feature is most effective when it is configured on the entire switched
network. Loop guard operates only on interfaces that are considered point-to-point by the spanning tree.
You cannot enable both loop guard and root guard at the same time. Note
You can enable this feature if your switch is running PVST+, Rapid PVST+, or MSTP.
This procedure is optional. Follow these steps to enable loop guard on the switch.
SUMMARY STEPS
1. Enter one of the following commands:
• show spanning-tree active
• show spanning-tree mst
2. configure terminal
3. spanning-tree loopguard default
4.
end
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
313
How to Configure Optional Spanning-Tree Features