We need to dive into a topic that is going to impact our production networks
for sure,
because when we look at Spanning Tree protocol, it was designed in an era when
networks were
very dynamic.
And so the assumption there was, hey, if the network changes by adding switches
and maybe
by reconfiguring switches that the Spanning Tree topology would change
appropriately.
But in modern networks, our topologies are pretty well established.
We usually have a dedicated distribution layer and dedicated access layers. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We usually have a dedicated distribution layer and dedicated access layers.
And so if I connect an access layer switch to the network and it's configured
with a
Spanning Tree priority of zero, maybe it had been used in a lab or something
along those
lines and someone was practicing their CCNA or CCNP skills and they configured
it with
a priority of zero.
And then we take that switch and plug it into the network, it's going to take
over as the
route, which is going to bring the entire network down while all of the ports
go through listening
and learning.
Even rapid Spanning Tree, we'd notice that it would go faster, but we'd still WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Even rapid Spanning Tree, we'd notice that it would go faster, but we'd still
have a
lot of problems.
And so Spanning Tree is unfortunately not going to help us out with native
configurations.
I can't tell Spanning Tree, hey, I want you to be the root no matter what.
I can set you to priority zero, but if the switch I connected, which also has
priority
zero, has a lower MAC address, it'll still take over.
And I can't tell Spanning Tree not to do that.
So fortunately Cisco has come to the rescue for us.
They've given us a series of mechanisms that we can use to protect the topology WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
They've given us a series of mechanisms that we can use to protect the topology
.
We're going to cover three of them here in this skill.
And the next skill we're going to find that Spanning Tree still has some
potential scenarios
that creates loops.
And so we'll talk about mechanisms that can help us with additional loop
protection.
But our focus here in this skill is going to be saying, I want to build out a
Spanning
Tree topology and I want it to lock in place.
Even if I connect a switch by accident and somewhere, I misconfigure a switch, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Even if I connect a switch by accident and somewhere, I misconfigure a switch,
or for
that matter, if somebody is nefariously trying to cause my network harm, I need
to be able
to protect the network in those situations.
And that's exactly what these mechanisms are going to do for us.