What you'll notice is spending tree convergence is very quick and that's because we running rapid pivot
plus.
I didn't make any changes on these switches.
From a spending tree point of view.
So the command show run pipe include span shows the default config.
And notice the spanning tree used is rapid pivot.
In the output it shows as always PTP or rapid spanning tree but this is actually rapid per VLAN spanning
tree.
We can change the mode of spanning tree.
But before I do that, just to make the point again at the moment.
Show spanning tree on switch three shows that the root port is gigabit zero one the sport.
If I shut that port down.
And then top shows spanning tree again.
What you'll notice is gigabit is zero, zero is the root put.
Convergence is very quick with rapid spending because it doesn't use timers.
So the max age and for delayed timers are not used for convergence.
The switches send messages to each other with rapid spanning tree to enable quick convergence.
So now if we change the spanning tree type or mode to PV ist, we should see that spanning tree takes
a lot longer to converge.
So I'll change that on all switches.
Switch three.
Switch for.
Switch five.
So back on switch three show spanning tree notice we can see that the switch is still learning which
ports are the root port, designated port or blocking port.
When in the learning state traffic will be blocked.
User traffic will only be forwarded when ports transition to the forwarding state.
At the moment you can see that the spanning tree protocol used or shown here is triple E.
But once again, you need to be careful because on Cisco switches, even though it displays triple E,
we actually using PVS, DT PVS, RT is once again backward compatible.
So it will be able to talk to an 802.1 DX switch from another vendor as an example, so we can see triple
E in the output here.
So once again show spanning tree.
The root port in this case is now gigabit zero zero.
So what happened?
Because previously we had switched one as the route.
It still has a command.
Show spending tree shows us that the switch is the root of the topology, but gigabit zero one is not
shown in the output here.
Because I need to know.
Shut that port.
So.
Confetti.
Interface gigabit.
Zero one.
No shut show spending tree.
Notice that port is a listing port.
Gigabit zero zero is a blocking port.
So this port is blocking this port is listening.
And what you'll notice is it'll take it a while to converge.
I'll put an IP address on the switch.
We'll be waiting and then I'll demonstrate this again.
Put an IP address on switch one.
While no shut the interface.
So paying 10.1 did 1 to 1 camping itself.
Switch three.
No.
Shut the interface paying ten .1. 1 to 1.
Ping succeeds, so I'll just do that again.
Notice the ping from switch three to switch one succeeds.
Show spanning tree convergence has taken place because gigabit zero one is the root port and is forwarding.
But now if I shut down gigabit zero one and then try and ping switch one.
The port has gone down, but pings are failing even though we have a redundant link show spanning tree
shows me that the root port is still learning.
Still learning pings fail.
PV ist takes a long time to converge.
Can take 30 seconds for that convergence to take place.
As you can see there, it's just happened.
Show spanning tree shows us now that gigabit zero one is forwarding.
But once again if I know shut gigabit zero one and did the ping again the ping would fail because it
now needs to learn that this is the better path.
So spending tree notice the root port gigabit zero one is in the listening state.
So we have listening, then we have learning and after a while it should go to forwarding.
But that can take 30 seconds.
So it's still learning.
Now it's gone to forwarding and now pings will succeed.
So ports have different states in a blocking state.
User traffic is not forwarded.
The switch doesn't learn MAC addresses based on frames received.
This is a stable state for a port.
A listening and learning port.
Do not afford frames either.
Listing ports don't learn MAC addresses based on frames received.
In other words, they don't update the MAC address table.
A learning port does update the MAC address table.
This is a temporary state or transitionary state.
While the switches learn the topology in a forwarding state, frames are forwarded, MAC addresses are
learnt and this is a stable state.
In other words, this is not a transitionary state.
The state will stay that way until there's a change in the topology.
A disabled port doesn't receive frames, doesn't forward frames, doesn't learn about Mac addresses
on a port, and this port will stay in that state until you enable the port.
Now, if we change that to rapid spanning tree, so spanning tree mode, rapid pivot, what we should
notice is that convergence takes place a lot quicker.
I'll only enable rapid spanning tree on switch one, two and three.
Show spending tree.
Rather show spanning tree.
Shows us that the spending tree mode now enabled is rapid per VLAN spanning tree.
We've got a path cost using gigabit.
Zero one.
So as you can see, gigabit zero one is the route port.
The switch.
Camping switch one.
I'll shut.
That put down.
And when we do a ping again, it instantly can ping switch one even though we've just seen the interface
go down in the output here because spanning tree converges a lot quicker when using a rapid spanning
tree.
So the moral of the story is that in the real world you want to use a rapid pivot rather than PV ist.