From: Dillon Yang (dillony@gmail.com)
Date: Tue Apr 12 2005 - 01:30:13 GMT-3
Hi, gladston:
Do a search, or
http://www.groupstudy.com/archives/ccielab/200405/msg00854.html
HTH
dillon
On Apr 12, 2005 4:19 AM, gladston@br.ibm.com <gladston@br.ibm.com> wrote:
> I found this statement on 4500 doc, but not on 3550 doc (I think it must be the same)
>
> ==============
> quoted
> By default, spanning tree sends BPDUs from all ports regardless of whether PortFast is enabled
>
> ===============
>
> Yet, I could not clarify this behavior:
>
> If the switch is configured with Portfast and the port receives a BPDU, what does happen?
>
> Based on the following doc, if the switch is configured with Portfast plus BPDU filtering, when the port receives a BPDU it loses its portfast status and bpdu filtering is disabled.
>
> ==========
> quoted
> Understanding BPDU Filtering
>
> The BPDU filtering feature can be globally enabled on the switch or can be enabled per interface, but the feature operates with some differences.
>
> At the global level, you can enable BPDU filtering on Port Fast-enabled ports by using the spanning-tree portfast bpdufilter default global configuration command. This command prevents ports that are in a Port Fast-operational state from sending or receiving BPDUs. The ports still send a few BPDUs at link-up before the switch begins to filter outbound BPDUs. You should globally enable BPDU filtering on a switch so that hosts connected to these ports do not receive BPDUs. If a BPDU is received on a Port Fast-enabled port, the port loses its Port Fast-operational status, and BPDU filtering is disabled.
> ===========
>
> Thanks for any feedback. I previously posted this doubt but reading some docs I saw this topic is not clear yet.
>
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