Administrator Guide
Figure 141. STP Loop Guard Prevents Forwarding Loops
Conguring Loop Guard
Enable STP loop guard on a per-port or per-port channel basis.
The following conditions apply to a port enabled with loop guard:
• Loop guard is supported on any STP-enabled port or port-channel interface.
• Loop guard is supported on a port or port-channel 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+)
• You cannot enable root guard and loop guard at the same time on an STP port. For example, if you congure loop guard on a port on
which root guard is already congured, the following error message is displayed: % Error: RootGuard is configured.
Cannot configure LoopGuard.
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Spanning Tree Protocol (STP)