Configure BPDU Guard
Configure BPDU Guard to block the root selection process or to prevent BPDU flooding from unknown devices.
Procedure
Example
Enable BPDU Guard on port 1/8, and specify a timer value of 200 seconds. Verify the configuration.
Switch:1>enable
Switch:1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Switch:1(config)#interface gigabitEthernet 1/8
Switch:1(config-if)#spanning-tree bpduguard enable
Switch:1(config-if)#spanning-tree bpduguard timeout 200
Switch:1(config-if)#show spanning-tree bpduguard 1/8
===============================================================================
                                   Bpdu Guard 
===============================================================================
Port      PORT         PORT                TIMER   BPDUGUARD    BPDUGUARD 
NUM MLTID ADMIN_STATE  OPER_STATE TIMEOUT  COUNT   ADMIN_STATE  ORIGIN
-------------------------------------------------------------------------------
1/8       Up            Up        200        0       Enabled    CONFIG   
Variable Definitions
Use the data in the following table to use the spanning-tree bpduguard commands.
| Variable | Value | 
|---|---|
| enable | Enables BPDU Guard on the port. The default is disabled. | 
| port {slot/port[/sub-port][-slot/port[/sub-port]][,...]} | Identifies the slot and port in one of the following formats: a single slot and port (slot/port), a range of slots and ports (slot/port-slot/port), or a series of slots and ports (slot/port,slot/port,slot/port). If the platform supports channelization and the port is channelized, you must also specify the sub-port in the format slot/port/sub-port. | 
| timeout <0, 10-65535> | Specifies the value to use for port-state recovery. After a BPDU guard disables a port, the port remains in the disabled state until this timer expires. You can configure a value from 10 to 65535. The default is 120 seconds. If you configure the value to 0, the expiry is infinity. | 
Use the data in the following table to use the show spanning-tree bpduguard command.
| Variable | Value | 
|---|---|
| {slot/port[/sub-port][-slot/port[/sub-port]][,...]} | Identifies the slot and port in one of the following formats: a single slot and port (slot/port), a range of slots and ports (slot/port-slot/port), or a series of slots and ports (slot/port,slot/port,slot/port). If the platform supports channelization and the port is channelized, you must also specify the sub-port in the format slot/port/sub-port. | 





