All right, let's jump into our challenge here.
What we're given is a set of switches in this triangle topology gives us a loop
, as well
as some priority values that are going to be used to help us determine which
switch is
the root.
The thing we have to keep in mind is that it's the lower value that wins, and
so the
lowest value that's listed here would be switch to, and as a result, it becomes
the
root bridge.
Now, it says we're to identify the roles, so our designated ports, our root
ports, our
non-designated ports. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
non-designated ports.
So what we're going to do is we're going to realize or remember that a root
bridge has
only designated ports, and those designated ports probably are going to connect
to root
ports.
In fact, if all of these links are created equal, which they are, as called out
in the
lab, then this is always going to be the case.
So we have designated port on the root connecting to a root port downstream.
Remember, downstream this way, and then upstream is going to be viewed from the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Remember, downstream this way, and then upstream is going to be viewed from the
other switches.
So traffic flows this way, and we can follow the flow of BPDUs in this regard.
So lastly, this is where we get into a situation, we're going to have to figure
out which port
to block, because both of these switches are going to send BPDUs to one another
, expecting
the other side to block.
And at this point, we're not given enough information to know which side is
going to
block.
And that's just because we haven't walked through the cost structure and how
exactly
these decisions are made yet. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
these decisions are made yet.
And the primary takeaway from this conversation is therefore, I just need to
recognize which
one of these ports, or which ones, are eligible.
So either of these are eligible.
One of them is going to be a designated port.
Let's just say switch one.
And one of them is going to be a non-designated port or a blocking port, which
is switch three.
So identify which ports are forwarding and which are blocking.
Well, all of them are going to be in a forwarding state, as long as traffic is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Well, all of them are going to be in a forwarding state, as long as traffic is
going across
the port.
The one exception, except, are non-designated port.
And so that would be this one right here.
This is going to be in the blocking state.
And so that's going to prevent the loop, which means we have an active link
here and an active
link here.
And that would be our loop free topology.
We're not going to use that link, even though, keep in mind that switch one
continues to send
BPDs and broadcast and flooded traffic for that matter down that link. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
BPDs and broadcast and flooded traffic for that matter down that link.
Now lastly, if a new switch is added into the topology here, what is the
initial state
of the port and what's the final state?
So remember our order, we're going to start off in the listening state.
And so that's the answer to the first question.
Then we're going to go to the learning state, which is in the middle, and then
we'll end
up on forwarding because by connecting this with a single connection, there's
no way for
that to be a loop.
And therefore, it will end up in the forwarding state. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And therefore, it will end up in the forwarding state.
So there's still a lot to explore as far as how decisions like which port are
we going
to block those decisions have to be made and we have to understand how those
decisions
are made.
At this point in the conversation, we should understand how the route bridge is
selected,
what the different route or port roles are, and how those look relative to the
route,
and then also what the different port states are, and especially understand
what the port
state transition looks like when we bring a port online.
I hope there's been informative for you and I'd like to thank you for viewing. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I hope there's been informative for you and I'd like to thank you for viewing.