Re: BPDU Filtering and PortFast Relationship

From: George Bekmezian (george@bekmezian.com)
Date: Fri Apr 20 2007 - 23:13:39 ART


It's probably done that way as a protective measure. Why not just enable
bpdu guard on the interface too?

George

WorkerBee <ciscobee@gmail.com>
Sent by: nobody@groupstudy.com
04/20/2007 09:23 PM
Please respond to
WorkerBee <ciscobee@gmail.com>

To
"Cisco certification" <ccielab@groupstudy.com>
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Subject
BPDU Filtering and PortFast Relationship

Hi Group,

This is something that confused me.

If "BPDU filtering" + "Port Fast" is enabled globally, why does a
switchport
loses it's Port Fast status as well as BPDU filtering when a BPDU
packet is received from that particular port?

If I want BPDU filtering protection and Port Fast status of a switch
port, why upon
receiving a BPDU from a PortFast port turned off both features?

So how can I ensure I still have PortFast enable and BPDU filtering
just block the BPDU packets from the PortFast port and yet has both
features enable without losing their status?

Reference link,

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3560/12235se/cr/cli3.htm#wp1946892

You should globally enable BPDU filtering on a switch so that hosts
connected to switch interfaces do not receive BPDUs. If a BPDU is
received on a Port Fast-enabled interface, the interface loses its
Port Fast-operational status and BPDU filtering is disabled.



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