BPDU received from Phone

Unanswered Question
Jan 28th, 2009

Hi all,

Strange thing happened few days ago.

I noticed one port on cat switch is in err-disable ,but what was connected to the port was an Avaya Phone.

The phone is not supposed to send BPDus right?

why did this happen?



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Giuseppe Larosa Wed, 01/28/2009 - 01:53

Hello Vlad,

but if someone connects a switch to the PC port of phone a BPDU is received on your switch and with bpu guard enabled the port is placed in errordisabled.

This happens because BPDUs have multicast MAC destination address.

We have seen this with cisco ip phones as a result of users trying to insert their own small switches

Hope to help


hunnetvl01 Wed, 01/28/2009 - 01:58

Hello Giuseppe,

I know this , but in my case there is only one Avaya phone connected to the port.

I went to the user and checked it myself.




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