portfast port and hub

Answered Question
Sep 14th, 2008
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hi every body!

I have some confusion about portfast port being connected to hub which(hub) is connected to another switch.

assuming bpdu guard is enabled on the portfast port. My book says loop will generate in this scenario and my point it should'nt becuase hub will receive the bpdu on the port connected to switch and repeats it on the port which is connected to portfast- enabled port of the other switch.Bpdu guard will kick in and disable the port. Am i right?

thanks a lot!

Correct Answer by Mark Yeates about 8 years 8 months ago

Sarah,

You are correct. As soon as either of the switchports connected to the hub receive a BPDU message from the other switch it goes into err-disable. With that being said whether portfast was enabled or not

BPDU guard will kick in and disable the offending port. There would not be a loop unless the switches were also directly connected to each other as well as connected to the hub.


HTH,

Mark


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Correct Answer
Mark Yeates Sun, 09/14/2008 - 15:29
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  • Gold, 750 points or more

Sarah,

You are correct. As soon as either of the switchports connected to the hub receive a BPDU message from the other switch it goes into err-disable. With that being said whether portfast was enabled or not

BPDU guard will kick in and disable the offending port. There would not be a loop unless the switches were also directly connected to each other as well as connected to the hub.


HTH,

Mark


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