spanning three protocol has been modified slightly since. It's origen to enhance it. And these are called spanning tree enhancement for the ccn A. We're gonna cover two of these enhancements.
The 1st 1 is your port fast feature. For example, if you have a switch, which one and you have a bunch of PCs connected to it
PC three. I'm just gonna draw three
spanning tree when this switch powers on spanning three star sending BP to use.
And how long does it take spanning tree to convert who go from blocking to listening to learning to fording?
Well, it takes 20 seconds. It remains in blocking for 20 seconds,
then for listening and learning. It's 15 seconds each for a total of 50 seconds. So it takes 50 seconds for spanning tree
to converge and to put the ports
from blocking to forging.
Now, do these species understands founding three BB to use? No, they don't. So will these species need to wait 50 seconds for this switch to convert spanning tree before the species can talk to each other? Yeah, they would, unless you use the port fast feature
on these ports connected to
the end hosts. What the port fast feature does is immediately transitions the port from blocking to 14. It skips all the spanning three states, so the poor does not transition from blocking to listening to learning to fording.
And the port does not wait 50 seconds. It immediately jumps into fording
that is your pork past feature. The second feature is your B P. D. You guard with the beating you guard feature.
It is used in conjunction with the port Fast feature. Now what if somebody with malicious intent unplugged this PC from this port? Let's say this is Port three
and attach their own switch at the other end. Switch X. We don't know.
Then they can get all your traffic that's running between PC one and PC to if they have the correct villain information.
So how do we guard against this?
Well, if we enable the BP Dugard feature on Port three as soon as BP news are received because switch excellent, it powers up will start sending bpd use correct.
So as soon as a B p. D. U is received on Port 34 tree will be put in air disabled mode or in other words, will be shut down.
the BP do you guard feature does. It's to prevent against malicious attack such a stiff.
Now, I'm gonna go ahead and show you the port fast feature and the BP Do you guard feature on