Spanning Tree Protocol | 1063Root Guard ConfigurationYou 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 thespanning-tree 0 rootguard command:To disable STP root guard on a port or port-channel interface, enter the no spanning-tree 0 rootguardcommand in an interface configuration mode.To verify the STP root guard configuration on a port or port-channel interface, enter the showspanning-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 stackingport.• 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 youconfigure root guard on a port on which loop guard is already configured, the following error message isdisplayed:% 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 blockedin all other MST instances.Task Command Syntax Command ModeEnable root guard on a port or port-channel interface.0: Enables root guard on an STP-enabled port assigned toinstance 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} rootguardINTERFACEINTERFACEPORT-CHANNEL
