DELL 9.7(0.0) User Manual

Figure 117. STP Root Guard Prevents Bridging Loops

Configuring Root Guard

Enable STP root guard on a per-port or per-port-channel basis.

Dell Networking OS Behavior: The following conditions apply to a port enabled with STP root guard:

• Root guard is supported on any STP-enabled port or port-channel interface.
• Root guard is supported on a port in any Spanning Tree mode:

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• When enabled on a port, root guard applies to all VLANs configured on the port.
• You cannot enable root guard and loop guard at the same time on an STP port. For example, if you 

configure root guard on a port on which loop guard is already configured, the following error 

message displays: • % Error: LoopGuard is configured. Cannot configure RootGuard.

• When used in an MSTP network, if root guard blocks a boundary port in the CIST, the port is also 

blocked in all other MST instances.

To enable the root guard on an STP-enabled port or port-channel interface in instance 0, use the 
following command.

• Enable root guard on a port or port-channel interface.

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Spanning Tree Protocol (STP)