Portfast and bpduguard

[Asif.oxy]

Hi,

I am little confuse in portfast and bpduguard concepts, i know when it is enter at interface level it transition the port to forwarding state(portfast) and if bpdu is received on port it is put in errdisable state(bpduguard), but i am not getting the concept when it is entered globally means if I say spanning-tree portfast default does it affect my trunk port and i have to explicitly say no spanning-tree portfast on my trunk port or not, same goes for spanning-tree portfast bpduguard default

does i need to specify no for trunk ports or not? please help!

Thanks

Asif 

[Mohsin Alam]

The spanning-tree portfast default global configuration mode command enables PortFast on all non-trunking interfaces. 

At the global level, you enable BPDU guard on Port Fast-enabled ports by using the spanning-tree portfast bpduguard default global configuration command.

So in a nutshell you don't have to use the no commands on trunk. 

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[Asif.oxy]

Hi Mohsiala,

I read the same answer on cisco press but i have noticed unusual behavior in packet tracer when i enable portfast and bpduguard at global level my existing trunk ports are put in err-disable state so i posted query in community, so is this packet tracer glitch or i am doing something wrong looking forward for your response.

[balaji.bandi · Accepted solution]

packet tracer when i enable 

Asi i know The tool for Lab get familiar with the soft features, you can not simulate/emulate  100% feature of hardware behavior.

[Mohsin Alam]

Packet tracer has some limitations and glitches always try in GNS or EVE! 

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