Service Manual

Table Of Contents
Figure 128. STP Root Guard Prevents Bridging Loops
Configuring Root Guard
Enable STP root guard on a per-port or per-port-channel basis.
Dell EMC 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 except when used as a stacking port.
Root guard is supported on a port in any Spanning Tree mode:
Spanning Tree Protocol (STP)
Rapid Spanning Tree Protocol (RSTP)
Multiple Spanning Tree Protocol (MSTP)
Per-VLAN Spanning Tree Plus (PVST+)
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.
INTERFACE mode or INTERFACE PORT-CHANNEL mode
spanning-tree {0 | mstp | rstp | pvst} rootguard
0: enables root guard on an STP-enabled port assigned to instance 0.
mstp: enables root guard on an MSTP-enabled port.
rstp: enables root guard on an RSTP-enabled port.
pvst: enables root guard on a PVST-enabled port.
To disable STP root guard on a port or port-channel interface, use the no spanning-tree 0 rootguard command in an
interface configuration mode.
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Spanning Tree Protocol (STP)