Re: bpdu-filter question

There are two things as Mr. Scott said:

If the feature is activated in global configuration mode using the
"spanning-tree portfast bpdufilter default" command, then the feature
is automatically activated on all PortFast-enabled ports. In this
case, after port is connected, it sends 11 BPDUs in usual intervals.
If no BPDU is received during this time or anytime after it, the port
will stop sending BPDUs. If a BPDU is received on such a port, the
Filter feature is deactivated for that port and the port becomes a
normal STP port - it again starts sending and receiving BPDUs in a
usual way.

If the BPDU Filter feature is activated directly on a port using the
command "spanning-tree bpdufilter enable", the port will never send or
receive BPDUs. If a BPDU is received on such a port, It will disable
the STP from this port which can cause bad looping in the network.

I also did this lab for bdpufilter and watch the behavior as mentioned above.

Regards,
Anser

On Thu, Nov 5, 2009 at 7:27 AM, Scott Morris <smorris_at_ine.com> wrote:
> The actions (or re-actions anyway) will depend on whether we apply the
> command on an interface or globally as default!
>
> Try it any play!
>
>
>
>
> *Scott Morris*, CCIE/x4/ (R&S/ISP-Dial/Security/Service Provider) #4713,
>
> JNCIE-M #153, JNCIS-ER, CISSP, et al.
>
> JNCI-M, JNCI-ER
>
> evil_at_ine.com
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> Joe Astorino wrote:
>> So far as I know bpdufilter will filter both incoming and outgoing
>> BPDUs...so it essentially is disabling spanning-tree on the port. As far as
>> enabling it on portfast enabled ports, are you sure you aren't talking about
>> bpduguard? That is pretty common so that if we get a bpdu on a port that
>> should be connected to a host we simply shut down the port.
>>
>> On Wed, Nov 4, 2009 at 10:23 PM, <Keegan.Holley_at_sungard.com> wrote:
>>
>>
>>> GS,
>>>
>>> I recently watched a recorded bootcamp that stated that bpdu filter will
>>> revert back to the default spanning tree behavior if it sees a bpdu. They
>>> also say should be enabled on port fast ports to avoid loops. I seem to
>>> have found conflicting documentation on cisco.com one page states that the
>>> bpdu's are blocked constantly and the other pretty much agrees with the
>>> vendor. I tried this on a 3550 running 12.2(40) see2 and bpdu's were
>>> blocked no matter what. Did this change across code releases/platforms or
>>> are they just wrong?
>>>
>>>
>>> Heads:
>>>
>>> http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_44_se/configuration/guide/swstpopt.html#wp1033638
>>>
>>> tails:
>>>
>>> http://www.cisco.com/en/US/docs/switches/lan/catalyst4000/7.4/configuration/guide/stp_enha.html
>>>
>>>
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Received on Thu Nov 05 2009 - 13:06:49 ART