2.7 Configure, verify and troubleshoot STP related optional features

2.7.a PortFast

Port fast disables STP on a port allowing the interface to start forwarding immediately by bypassing STP safety checks.

This should be used with caution and only on ports NOT connected to other switches!

IOU1(config-if)#spanning-tree portfast

 

2.7.b BPDU guard

BPDU guard will immediately place the port in an err-disabled state if it detects and STP BPDUs on that interface.

Enable BPDU guard if enabling PortFast.

IOU1(config-if)#spanning-tree bpduguard enable 
IOU1(config-if)#
*May 6 13:59:00.436: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0/0, changed state to down
IOU1(config-if)#
*May 6 13:59:01.436: %LINK-3-UPDOWN: Interface Ethernet0/0, changed state to down
IOU1(config-if)#^Z
IOU1#show inf
*May 6 14:00:13.974: %SYS-5-CONFIG_I: Configured from console by console
IOU1#show int e0/0
Ethernet0/0 is down, line protocol is down (err-disabled)

 

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