From: mani poopal (mani_ccie@yahoo.com)
Date: Thu Apr 07 2005 - 17:00:19 GMT-3
Hi,
BPDU filtering will not send or receive bpdu's but when you enable bpdu guard and when superior bpdu's are received on that interface, the interface will go to errdisabled state(shutdown)[should wait for the timer to elapse or shut/no shut manually]
The BPDUguard can be enabled globally or on an interface basis, when you enabled globally, it will only apply to interfaces that are already configured for portfast. But when you enabled on specific interfaces, the portfast feature will be automacally enabled.
HTH
Mani
gladston@br.ibm.com wrote:
Any help trying to understand this Cisco explanation highly appreciated.
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quoted
Understanding BPDU Filtering
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.
http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12225seb/scg/swstpopt.htm#wp1046220
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So does it mean that a port configured with just Portfast (no bpdu filtering) will send BPDUs?
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quoted
If a BPDU is received on a Port Fast-enabled port, the port loses its Port Fast-operational status, and BPDU filtering is disabled.
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Can I understand it as "if a port is configured just with Portfast, if a BPDU is received, nothing is done."
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quoted
At the interface level, you can enable BPDU filtering on any port without also enabling the Port Fast feature by using the spanning-tree bpdufilter enable interface configuration command. This command prevents the port from sending or receiving BPDUs.
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The behaviour of 'interface level' is the same of 'global configuration" on the sense that "If a BPDU is received on a Port Fast-enabled port, the port loses its Port Fast-operational status, and BPDU filtering is disabled."?
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