Bpduguard

[Jeremy_Tessenshon]

Hi All,

I have a recent incident at my workplace whereby a user plugged in hub and stacked another hub on top of it and caused network loop to occur.

The interface connected to the hub itself has already been configured to swithport bpduguard enable.

Currently my understanding is that while bpduguard itself can't err-disabled the port once the hub is plugged in since the hub itself doesn't send out bpdu.

However, that doesn't explain well on how does the looping occur on the network itself since there's no loop on the hub itself. Could the stacked hub on top of one another that caused the looping?

Please advice. Thanks.

[tironevi]

How was the stacked hub connected? If redundant connections were used between Hub1 and Hub2 then that can cause a storm.  Also, if the the second hub had a connection to a switchport, then that too can cause a loop.

A hub like a switch will forward a broadcast or multicast out every port except the port it received it from.

Regards,