Loop Guard

ReardenRearden Member Posts: 222
in CCNP
Hi, quick question on loop guard. Basically, a port with loop guard enabled that was receiving BPDUs goes into loop-inconsistent state once it stops receiving BPDUs, right? This state is similar to blocking, according to the BCMSN book. So does it just remain in that state until it receives a BPDU on that port, however long that might take?

Thanks for any clarification.
More systems have been wiped out by admins than any cracker could do in a lifetime.
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Comments

  • APAAPA Member Posts: 959
    Loopguard picks up on software errors where the link may become uni-directional even though physically the link is still up so when a non-designated port stops receiving BPDU's it is put into loop-inconsistent state to stop that non-designated port from going into the forwarding state.

    Once BPDU's are received again on the ND port then it will auto recover and transition through STP states according to the received BPDU.

    So yeah it is effectively blocked until it starts receiving BPDUs again....... UDLD picks up on physical layer uni-directional issues and Loopguard picks up on software errors causing uni-directional issues.

    Hope this helps :)
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  • ReardenRearden Member Posts: 222
    It does. Thanks :)
    More systems have been wiped out by admins than any cracker could do in a lifetime.
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