Cisco Catalyst 2960-X Command Reference Manual page 93

Layer 2 Commands
Do not enable root guard on interfaces that will be used by the UplinkFast feature. With UplinkFast, the
backup interfaces (in the blocked state) replace the root port in the case of a failure. However, if root guard
is also enabled, all the backup interfaces used by the UplinkFast feature are placed in the root-inconsistent
state (blocked) and are prevented from reaching the forwarding state. The UplinkFast feature is not available
when the switch is operating in the rapid-PVST+ or MST mode.
Examples
This example shows how to enable root guard on all the VLANs associated with the specified interface:
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# spanning-tree guard root
Related Commands
Command
spanning-tree loopguard default
OL-29043 -01
Description
Enables loop guard on all ports.
Catalyst 2960-X Switch Layer 2 Command Reference, Cisco IOS Release 15.0(2)EX
spanning-tree guard
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