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Forum Replies

  1. Hi Rene,

    Do you know what exactly happens when BPDU filter and Guard are both enabled on aportfast enabled interface and then a BPDU’s are suddenly received? I cannot find a clear answer on that anywhere. I read that BPDU filter takes precedence over BPDU guard when both configured on the interface, but it is still unclear to me what happens when in this case bpdu’s are received on a port configured this way.

  2. Hi Edwin,

    I just labbed this up. When you enable BPDU filter & guard at the same time then filter takes precedence. The BPDUs are ignored, the interface doesn’t go in err-disabled because of BPDUguard anymore.


  3. Hi Rene ,

    Global: if you enable BPDUfilter globally then any interface with portfast enabled will not send or receive any BPDUs. When you receive a BPDU on a portfast enabled interface then it will lose its portfast status, disables BPDU filtering and acts as a normal interface.

    What does it mean of "disables BPDU filtering and acts as a normal interface " ?

    “Interface: if you enable BPDUfilter on the interface it will ignore incoming BPDUs and it will not send any BPDUs. This is the equivalent of disabling spanning-tree.”

    What if there is portfast enabled on t

    ... Continue reading in our forum

  4. Sims,
    What does it mean of “disables BPDU filtering and acts as a normal interface ” ?

    It means that the switch realizes either there has been a change in topology, or the administrator has made an error. A BPDU should never be received on an interface on which BPDU filtering is enabled. When the filtering is enabled globally, this is a safety mechanism so that when a BPDU is received on a port where the global filtering was enabled, the Switch knows there must be another switch on the other side. In order to prevent a possible loop, the BPDU filtering is tu

    ... Continue reading in our forum

  5. Hi Waqar,

    its other way around:-

    1. if you configured BPDFilter globally with portfast it will only filter sending BPDU but it will accept incoming BPDU.
    2. if you configure per interface it will not send nor accept any BPDU its like turning off STP.


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