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| 3.7 |  | Tuning, Verifying, and Troubleshooting Spanning-Tree Protocol |
| 3.7.5 |  | Configuring root guard |

Root guard enabled on an interface applies to all the VLANs to which the interface belongs.

Do not enable the root guard on interfaces to 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. Root guard and loop guard cannot both be enabled at the same time.

This feature can be enabled if the switch is running PVST or MSTP. The MSTP feature is available only if the EI installed on the switch.

Beginning in privileged EXEC mode, follow the steps outlined to enable root guard on an interface.

To disable root guard, use the no spanning-tree guard interface configuration command.