It's time for us to cover the second set of enhancements that Cisco made to
Spanning
Tree which involve two different techniques.
They are UDLD, Unidirectional Link Detection and Loop Guard.
Now oftentimes we look at that along with Root Guard and BPDU Guard.
We've got all of these different special features.
We're just trying to keep them straight in our heads.
What do they all do?
And so it's important for us to recognize that there is this dividing line so
to speak.
We just covered the concept of topology protection. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We just covered the concept of topology protection.
Root Guard and BPDU Guard are all about making sure that our root stays the
root.
That we don't make switches that just show up on the network into the root and
cause
a whole convergence event and all of those kinds of things.
So we protect our root.
We protect ourselves from unauthorized BPDUs and especially switches connecting
.
That's topology protection.
But now we have another situation on our hands.
We have all of these protection mechanisms to protect loops.
So it's the whole point of Spanning Tree is to protect our network from loops. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So it's the whole point of Spanning Tree is to protect our network from loops.
And yet there are a few very corner case scenarios where loops can form.
And we could roll the dice and say, "Hey, hopefully none of these scenarios
ever happen
to us."
It's like saying we were at a 99, maybe even 99.99% success rate at protecting
loops.
Is that good enough?
Well, for a lot of organizations, unless it's 100%, it's not good enough.
And that should be our perspective.
Even if some of these scenarios are unlikely to occur, they could occur and WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Even if some of these scenarios are unlikely to occur, they could occur and
they could
create loops even though we're running Spanning Tree protocol.
So Cisco recognized that there are a few flaws with the Spanning Tree logic and
those
flaws continue to exist even within the world of rapid Spanning Tree.
So just like with the topology protection mechanisms, these loop protection
mechanisms
were about to cover, UDLD and loop guard, these are going to be useful to us
even as
we move into a rapid Spanning Tree and potentially MST if we're running it.
But again, let's think about it in two separate groups. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But again, let's think about it in two separate groups.
We've got our topology protection group over here.
We've already covered that.
Now it's time to jump into our loop protection.
We want to look at the very few cases where Spanning Tree doesn't quite cut it
and use
these techniques in order to ensure that even in those scenarios we don't
create loops on