Dell PowerEdge M805 - Manual (Page 483)

Spanning Tree Commands 475
Due to configuration error of the maintenance personnel or a malicious user attack, a designated
root of the network may receive a BPDU with higher priority and lose its status as a root, which
causes undesired changes of network topology. Such unpermitted changes may pull the higher-
speed traffic to lower-speed links and cause network congestion.
To avoid such a problem, RSTP provides a Root protection function. After being configured with
Root protection, a port remains a designated port. Once this port receives a BPDU with higher
priority, it turns to listening status and does not forward any packets (as if the link to it is
disconnected). It resumes normal status if it receives no BPDU with higher-priority for a period of
time.
Syntax
spanning-tree root-protection
no spanning-tree root-protection
Default Configuration
Root protection is not enabled.
Command Mode
Interface Configuration (Ethernet, Port-Channel) mode
User Guidelines
This command has no user guidelines.
Example
The following example enables the Root protection function on the switch.
console(config-if-1/g5)#spanning-tree root-protection