Hi Guys..
I hv a confusion in my mind. Plz help me to clear my concept.
How a port respond when a PortFast port receives any BPDU.
Please make sure that BPDU Guard, ROOT Guard are not
considered in this scenario. Just a spanning tree without
any enhancement.
Will the port goes through STP port state??? As we knw that
PortFast bypass the Listening & Learning State? How it will
respond when a BPDU (Inferior or Superior) is received on
that Port.
Thanks in advance. Waiting for Replay.
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Answer Posted / jitu
Yes, this really is the case. However, I do think there is
some confusion as to what happens to a Portfast enabled port
when it receives a BPDU. Upon receipt of a BPDU on a
Portfast enabled port, the port will immediately loose its
PortFast feature. This does not mean that the port will
show Portfast disabled in the "show spanning-tree summary"
output. Rather it means it will act as a normal STP port
and transistion through the STP states and will eventually
end up in either a blocking state or a forwarding state.
If the BPDUs that were arriving on the port were
"non-superior" BPDUs, the port would transistion to the
blocking state. Once these BPDUs stop the port would
recover and again participate in Portfast.
If the BPDUs that were arriving on the port were "superior"
BPDUs (means a lower bridge priority), then the port would
transistion to the forwarding state. This can cause a
permanent STP recalculation throughout your switch network.
Enabling BPDU Guard in addition to Portfast will prevent
bridging loops and/or topology changes from happening,
because upon receipt of BPDUs (superior or not), the BPDU
Guard feature immediately err-disables the port and must
manually be reenabled.
Right Mr... sahin ( hehhehe)
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