- In this video,
we're going to take a look at how to configure
Rapid Spanning Tree Protocol
or specifically Cisco's variant of that,
which is Rapid PVST plus
as we discussed in our last video.
Let's see what our current spanning-tree mode is right now.
Let's do a show, spanning-tree summary command
and it says that currently we're in MST mode.
Remember we set that up a couple of videos back.
Well let's change that on all of our switches.
Let's go into Global Configuration mode
and we'll say spanning-tree mode
and the context-sensitive help
shows that we've got an option of Rapid PVST.
And notice I say it's PVST plus
but it just says PVST there.
The plus means that we're interconnecting our switches
over a Dot1q trunk,
which is typically what we're doing.
So I call it Rapid PVST plus
but really that's just a specific type of Rapid PVST.
Let's set this up on all of our switches.
Notice I'm getting some error messages on screen
because we have mismatched modes right now.
Let's say spanning-tree mode,
Rapid PVST
and let's go to switch SW3, same thing.
It's gone to global configuration.
Spanning-tree mode, Rapid PVST.
Hopefully the error messages will settle down
after we made those changes
and everybody's running in that Rapid PVST mode.
In fact, let's do a quick confirmation of that.
Let's do a show spanning-tree summary
and just confirm that.
Yes, indeed.
The switch is in Rapid PVST mode, excellent.
Now, when it comes to influencing which switch
is going to be the route for which VLANs,
it works exactly like it did for PVST plus
that we learned about back in our CCNA studies.
For example, let's go over
to switch SW1
and let's say that on SW1,
we want this to be the root bridge for VLANs 100 and 300
and we want it to be the secondary route bridge
for VLAN 200.
Here's how we could configure that
exactly like we did back in our CCNA studies.
We're going to say spanning-tree VLAN
and I'll say 100, 300 root primary.
I want it to be the primary route for those two VLANs.
Spanning-tree VLAN 200 route secondary
is going to make me the secondary route for that VLAN.
Now let's go over to switch SW3
and let's make it the root,
the primary route for VLAN 200
and let's make it the secondary route for VLANs 100 and 300,
so a very similar configuration.
It's gone to global configuration mode
and I'll spanning-tree VLAN 200 route primary,
spanning-tree VLAN 100, 300 root secondary
and then we'll do a show spanning-tree summary
and we'll see that we are the root for VLAN 200, excellent
and if we go over to switch SW1
and I do a show spanning-tree summary,
we'll see that I am the root for VLANs 100 and 300.
Now, let's zoom in on one of those VLANs
to see the different link types that we have.
We talked about link types in our prior video.
Let's go into VLAN 300.
We're at the roots for VLAN 300
so I'm assuming that we're going to be forwarding
on all those ports belonging to VLAN 300 or two trunk ports.
I'll say show spanning-tree VLAN 300
and yes we are.
We're forwarding on both of those ports
and their designated ports.
Remember that each link,
whether it's passing data or not, has a port
that's the designated port
and it's the port on that link
that's closest to the route in terms of cost,
but we'll get closer to the route than being on the route
and we are, tells us very clearly right here,
we are the route for this VLAN.
We'll also notice that the type of link
we have in each case is P2p,
that's a Point-to-point link type
and the reason it says P2p
is because we're running in full duplex.
If we had had these ports configured for half duplex,
the switch would have assumed
that we were connecting to a shared media hub.
So the link type would be shared
instead of Point-to-point.
However, if we had a port connecting to an end device
like a PC or an IP phone,
it would still in most cases be running in full duplex,
so we would also be a Point-to-point link type
but how would we make that port an edge port
on that Point-to-point link?
Let's take a look at some context sense of the help.
It's not super straight forward.
We talked about it in our last video
but it's not super straight forward
on how to make that an edge port.
If we go into global configuration mode
and let's go into a port that we're not using right now,
I'll say interface, fastethernet1/0/1.
I don't actually have anything connected there
but if I do a spanning-tree link type question mark,
notice that I can hard-code link types of Point-to-point
and shared, I can not hard-code any sort of edge port mode.
How do we do that?
Well, it's not with this command,
it's with our PortFast configuration.
If we go into this interface
and say, spanning-tree portfast,
where we're saying,
I don't want to wait for the normal blocking, listening,
learning or any of those delay states
of spanning-tree protocol,
I just want to go active almost immediately
because I'm connecting to an end device.
I promise I'm not going to connect you to a switch.
You'll never see a BPDU coming in on this port.
Just go active almost immediately.
That's what portfast does
and by enabling a portfast,
that's how we make a port, an edge port.
Let's finish the command out there.
Spanning-tree portfast
and that's a look at how we can configure
Rapid Spanning-Tree Protocol.