So let's look at that practically.
Yeah I've got to switch one switch to and switch three switch to switch three or connected to a hub.
So that's following the typologies shown in this Cisco guide.
I've just booted up the switches so you can see that coming up at the moment.
So these are brain switches with no configuration at all.
OK so in switch one set to the host name to switch one switch to set the host name to switch to.
You may be able to hear that by C.P. you is maxed out all the switches are booting up at the moment
my genius 3 VM is at 87 percent the local CPQ 62 percent but that'll settle down in a moment which it
now has so schola shows spanning tree shows spanning tree at the moment to the switches not to the route.
You can see it's a path cost to get to the route on gigabit.
0 1 so I'm assuming that switch 3 is the route.
Show spending tree we can see in the output here.
That to switch three is the route to switch of the topology.
So I'll change that Nick.
I'll just touch one and top spending tree.
Vigeland One bricht And actually I'll just set it by priority so priority and let's set it to zero.
So show spanning tree we can see that the switch is now the root of the spinning tree for villaine one.
We are running Reppert Peavey's on the switch.
Some ports are still in the learning state.
But there they go to Fording.
So we can see all ports in the switch all forwarding.
Those are the two ports of interest and which one
on switch to show spending tree
so is the commission show spending tree we running Reppert spending tree Poth just to get to the root
is 4 out of portal 1 which is kickabout 00 gigabit 00 is the root port.
And notice how gigabit is 0 1 is the old turn of port on the switch.
It's in the blocking state.
That's what we learnt in the Cisco document.
An alternate port on the switch means that there is a port on another switch that's the designated port.
In other words it has a better path to get to the root bridge.
So let's look at Switch three shows spending tree on switch three.
It has a path to fall out of port 1 which is gigabit 0 0.
So this is the route port of switch three.
We can see that here once again gigabit 0 0 is the root port and the output to Gigabit is 0 1 is the
designated port and gigabit.
0 2 is the backup port backup port is in the blocking state alternate port on switch to is in the blocking
state.
So this port is blocking this port is blocking.
This is the only port that is forwarding on this segment connected to the hub.
So loops will be blocked in the apology even though we connected to a hub that demonstrates the port
roles and status that you get interrupted spending tree on switch to once again just move this up a
bit.
So on switch to connect to the hub on gigabit 0 1 gigabit 0 1 is an old turn at port.
That is the role the status of the port is blocking gigabit 0 00 on that switch is a recruit port.
That is the role and the status is forwarding on switch 3 gigabit 00.
This port is the root port.
It has a status of forwarding.
That's the best port to use to get to the root bridge.
Gigabit is 0 1.
In other words this connection is the designated port.
The role is designated the status is forwarding this interface gigabit to 0 2 is a backup port.
That is the role the status is blocking.
So blocking or discarding to use the industry standard term is the state of alternative as well as backup
ports router ports and designated ports have the forwarding status in a stable topology a state of learning
means that traffic is still being discarded on the port.
So as an example
on gigabit 00 I'll shut the port down show spending tree notice gigabit to 0 or 1 is now forwarding
gigabit to 0 2 is the alternate port.
It's in a blocking state
the port here is now the designated port.
It's in the learning status which will hopefully move to forwarding in a moment.
And there you go.
The reason why it took time to transition to the forwarding state is that this is a shared port not
a point to point Port point to point ports transition immediately to forwarding Schade ports.
Don't they have to go through the timer's of learning and then forwarding.
So scrolling up we saw a learning state and then it went to the forwarding state.
That's because it's a shared port which means a half duplex interface which is connected to a hub.
This port should be configured as a point to point link because it's a direct connection from one switch
to another.
So as an example what we should be doing is on gigabit 00 we should top spending tree linked type point
to point and we want to do that on both sides.
Typically in the real world your switches would negotiate a point to point link if the Duplaix was set
to full we'll do something similar on switch three gigabit 00 should be point to point and gigabit 0
1 should be point to point.
In other words this link point to point the Slinky's point to point.
So back on switch to shows spending tree noticed the port type point to point which allows for quicker
convergence on which one show spending tree both gigabit 00 and gigabit zero one point to point links.