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Spanning Tree Protocol | 1063
Root Guard Configuration
You enable STP root guard on a per-port or per-port-channel basis.
To enable the root guard on an STP-enabled port or port-channel interface in instance 0, enter the
spanning-tree 0 rootguard command:
To disable STP root guard on a port or port-channel interface, enter the
no spanning-tree 0 rootguard
command in an interface configuration mode.
To verify the STP root guard configuration on a port or port-channel interface, enter the
show
spanning-tree 0 guard
[interface interface] command in global configuration mode.
SNMP Traps for Root Elections and Topology Changes
• Enable SNMP traps for Spanning Tree state changes using the command snmp-server enable traps stp.
• Enable SNMP traps for MSTP using the command
snmp-server enable traps xstp.
FTOS 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.
• Root guard and loop guard cannot be enabled 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 is
displayed:
% 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.
Task Command Syntax Command Mode
Enable root guard on a port or port-channel interface.
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.
spanning-tree {0 | mstp | rstp |
pvst} rootguard
INTERFACE
INTERFACE
PORT-CHANNEL