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BPDUFilter vs BPDUGuard

after1111
Level 1
Level 1

Ive been reading a number of articles, some says you need to put bpdufilter on access ports, some says you need to put bpduguard on access ports.

The
commands  almost seem to serve opposite purposes - one shuts the port down if
a bpdu  is detected, the other obstensibly ignores bpdus.  Which one of these
commands  takes precendence?

Im confused.

Which one do I use for accessport and which one do I use for trunk port?

The other day I tried bpdu guard on both side of the trunk, the ports immediately went to err-disable mode.

1 Reply 1

Jon Marshall
Hall of Fame
Hall of Fame

after1111 wrote:

Ive been reading a number of articles, some says you need to put bpdufilter on access ports, some says you need to put bpduguard on access ports.

The
commands  almost seem to serve opposite purposes - one shuts the port down if
a bpdu  is detected, the other obstensibly ignores bpdus.  Which one of these
commands  takes precendence?

Im confused.

Which one do I use for accessport and which one do I use for trunk port?

The other day I tried bpdu guard on both side of the trunk, the ports immediately went to err-disable mode.

You absolutely don't want BPDUGuard on trunk links because usually trunk links connect up 2 switches and you want them to receive and send BPDUs. BPDUGuard should be enabled on ports that you do not want to receive BPDUs on ie. you can use BPDUGuard an apply to all ports connecting to end devices such as PCs/servers etc. That way if someone connected a switch or created a loop with a hub the port would see BPDUs and disable it. BPDUGuard is the more commonly used.

BPDUFilter is less commonly used. In effect it turns off STP on that port.

Jon

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