All right, back into the lab we go.
We are going to configure a trunk.
We're going to leverage DTP to create a dynamic trunk on one side and we're
going to create
a router on the stick on the other side of switch one.
In fact, let's go ahead and start by taking a look at the topology to make sure
that we
know what it is we're setting out to do.
So when we look at the goals for this lab challenge, the first task is to
create a trunk
between switch one and switch two using DTP.
So we're going to use DTP in here and we're told to allow switch one to WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we're going to use DTP in here and we're told to allow switch one to
initiate a connection
and switch two to more or less accept it to wait for the initiation.
That means that I'm going to have to configure these for switch mode dynamic,
but then also
specifically switch one is allowed to be in that desirable state and switch two
's gig
zero zero interface will have to be in the auto state.
We should see that this forms a trunk and we can confirm that with commands
like show
interface trunk or show interface switch port. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
interface trunk or show interface switch port.
So we'll take a look at that.
Meanwhile, then from there, we're told that we're going to create a static
trunk up to
the router.
Now this involves two different types of commands because on a switch we're
going to use switch
port commands and on the router we're going to use sub interface commands.
And so what this looks like is that since also the router doesn't run DTP, I'm
going
to just place this into a static trunk operation.
So switch port mode trunk and then on gig zero zero, I'm going to create two WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So switch port mode trunk and then on gig zero zero, I'm going to create two
sub interfaces.
I'm going to create gig zero slash zero dot 10 and gig zero slash zero dot 20.
And then from there, we're going to want to create some layer three interfaces
and we'll
come back to the diagram later to sort of see what it is we're trying to
accomplish.
So let's flip over to our configuration now and let's start with our switch
configurations.
So we're going to get on to switch one here and I'm going to do a config T and WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we're going to get on to switch one here and I'm going to do a config T and
get on
to interface gig zero zero.
I'm going to do switch port not switch port mode trunk, but switch port mode
and do a
question mark, we see we've got the option for dynamic.
So I'm going to do that dynamic and then we see auto and desirable are our
options.
So I'm going to set this to desirable on this side.
And the funny thing is is that switch to now we have to configure this.
Oops, I lost my connection to switch to.
And when I do a show, run interface on gig zero slash zero, we're going to see WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And when I do a show, run interface on gig zero slash zero, we're going to see
that there
isn't any default configuration there that's listed, but we're actually running
in auto.
If I do a show interface gig zero slash zero switch port, this is a very
powerful command
to see all the layer two configurations are happening.
And we notice the administrative mode is dynamic auto.
So when I do a config T interface gig zero zero and then switch port mode WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So when I do a config T interface gig zero zero and then switch port mode
dynamic auto.
Now I can take a look at show, run interface gig zero slash zero and there's
nothing there.
Why is there nothing there?
Well, because that is the default configuration, I didn't change the default
configuration
and instead we were just going to continue running in the mode in which we were
running.
So next question, are we running this in a trunk?
So I can do a show interface trunk to find out if we're running in a trunk. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So I can do a show interface trunk to find out if we're running in a trunk.
And we do see something pretty interesting here that first of all we are
running in a
trunk, but notice the encapsulation that we're using.
We're actually using that ISL that we talked about.
Now in modern switches, this won't happen.
We don't need to worry about this on catalyst nine case.
But if I come over to switch one and say show interface trunk, we're also going
to see
that we're running as a negotiated ISL connection.
So what's the solution to this?
Well, I simply need to get onto my interface here and use a switch port encaps WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Well, I simply need to get onto my interface here and use a switch port encaps
ulation switch
port trunk encapsulation and then specify, because I do a question mark here,
we'll see
that it's .1Q versus ISL.
And guess what Cisco has as the default?
Well, that's seen the default is ISL and that is just legacy configuration on
the more
legacy platforms at this point.
We can just say .1Q, but on catalyst nine case, this command isn't even WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We can just say .1Q, but on catalyst nine case, this command isn't even
available because
ISL has been removed from modern switches.
So because I've specified the encapsulation on the initiating side, if I do a
show interface
trunk, we're going to find that now I'm not negotiating.
I'm just hard set to .1Q.
I'm still in that desirable state and I am currently trunking.
So if I go to switch to now, let's run that same command on switch to and we'll
see that
we have negotiated to .1Q.
I did not have to specify the encapsulation on this side, although I could, but WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I did not have to specify the encapsulation on this side, although I could, but
that N
implies or is really saying that we have negotiated 802.1Q.
So it's kind of a fun little nuance to using DTP is that it will negotiate the
trunking
encapsulation type on older platforms where ISL is still an option.
Now next, we have to configure our trunk to router one.
And so that is once again on switch one.
We look at our diagram and we know that we need to perform this configuration WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We look at our diagram and we know that we need to perform this configuration
on interface
gig zero slash one.
At this point, I'm going to go ahead now watch if I do switch port mode trunk,
we're
going to find that it's been rejected because we need to first of all specify
the encapsulation
method.
So I'm going to say switch port encapsulation switch.
I forgot trunk again.
So we're going to support trunk encapsulation dot one Q and now we'll try
switch port mode
trunk. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
trunk.
And now we are running in a statically configured trunk operation.
Again, on modern platforms, we don't need to worry about specifying the encaps
ulation
method, but on these older platforms, we absolutely do.
So that's something to keep in mind.
But at this point, we are not only trunking, but we see that this environment
has been
prepared for us VLANs 10 and 20 are allowed in forwarding out all of our trunk
interfaces.
And so let's go ahead and now configure our router. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so let's go ahead and now configure our router.
So we said that we need to create sub interfaces on this router.
If I do a show run interface on gig zero zero, this is our interface facing the
switch one.
And we notice it's in layer three operation.
And that's because routers can't run interfaces in layer two.
There are some advanced configurations where you can emulate bridge
environments using
BVI's bridge virtual interfaces.
We're not going to go there.
But generally speaking, what we need to do here is not try to enable layer two WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But generally speaking, what we need to do here is not try to enable layer two
such
that it's somehow turns the router into a switch.
Instead, I'm going to create those sub interfaces.
So let's go ahead and do that together.
I'm going to do a config T. And the way we do that is I act like I'm getting
onto the
interface.
I'm going to get dot and now I can specify whatever ID I want within the
massive range
that they give us.
So usually we like to align this with the VLAN tag we're going to use.
So I'm just going to say interface gig zero slash zero dot 10.
And then from here, I'm going to map the VLAN ID to the sub interface. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And then from here, I'm going to map the VLAN ID to the sub interface.
This command was provided to us in the command reference here in the skill.
And that command is encapsulation encapsulation dot one Q and then I specify
the tag ID.
So for this, I'm going to call this VLAN 10.
And then if VLAN 10 is the native VLAN on the other side of this trunk link,
then I
can specify that here.
But since I didn't configure native VLAN, I'm just going to hit enter and then WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But since I didn't configure native VLAN, I'm just going to hit enter and then
interface
gig zero slash zero dot 20 to create the VLAN 20 side.
And once again, encapsulation dot one Q 20.
So at this point, I've configured the sub interfaces.
Let's go ahead and go back to our topology though, because we are not yet doing
any or
able to do any kind of pain testing.
And the reason for that is we haven't actually created any IP addresses or
layer three interfaces
on the switches. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
on the switches.
So what do we have?
Well, by creating these sub interfaces, I have created layer three interfaces
on this router
that are sort of virtual interfaces.
We can think of them like VLAN interfaces because they're not physical.
They're these virtual sub interfaces that are sort of behind the physical gig
zero slash
zero interface.
And these are fully functioning layer three interfaces.
That's why I've drawn them as dots here.
So I can place IP addresses onto these interfaces. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So I can place IP addresses onto these interfaces.
In fact, we're told to map the dot 100 IP address to each one of these
interfaces.
So let's go ahead and go back to our topology here.
And we will do that interface gig zero slash zero dot 10.
And then IP address and the subnet we're using is that 10 dot zero and for VLAN
10
be dot 10 and then dot 100 and then slash 24. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
be dot 10 and then dot 100 and then slash 24.
And let's go into a no shut and then into gig zero slash zero dot 20 IP address
this time
10 zero 20 dot 100 slash 24.
No shot.
All right.
So my layer three interfaces should be online.
If I do a show interface gig zero slash zero dot 10, we should see that it's up
and up
and it is I'll check without 20 and it's also up and up.
So once again back to our topology here, I have these two layer three WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So once again back to our topology here, I have these two layer three
interfaces, but
I can't ping anything.
There's nothing for me to ping because I don't have any layer three interfaces
down here.
So what can I do?
Well, as the last task indicates, we want to create some SVIs.
Now the switch one SVI is kind of interesting compared to the switch to SVI
because the
switch one SVI is meant to go on VLAN 10.
And so I'm going to map this interface to the same subnet so to speak as or the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so I'm going to map this interface to the same subnet so to speak as or the
same
VLAN as subnet sub interface gig zero slash zero dot 10.
And so naturally I could also connect other hosts into VLAN 10.
We can start to create our logical diagram if we want, but gig zero slash zero
dot 10
should be able to communicate with the SVI for VLAN 10 on switch one.
Meanwhile, switch to we're going to create this SVI for VLAN 20 and I should be WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Meanwhile, switch to we're going to create this SVI for VLAN 20 and I should be
able
to ride this trunk all the way up and connect in from a layer three perspective
to router
ones gig zero slash zero dot 20 interface.
And so we're going to map dot one to switch one and dot two to switch to.
So let's go ahead and do that and wrap this up.
So I'm going to come to switch one, do a config T interface VLAN 10 IP address WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So I'm going to come to switch one, do a config T interface VLAN 10 IP address
that same
dot zero dot 10 subnet and then this case it's dot one and we'll do a no, no
shot there
and then on to switch to interface VLAN 20 IP address is going to be the zero
dot 20
subnet dot two for switch to and then no shot. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
subnet dot two for switch to and then no shot.
So given that the topology is all online, the song is these interfaces come up,
we should
be able to ping.
So I should be able to ping from switch to router ones interface that's in the
same
subnet.
So that would be 20 dot 100 and there we go.
We have our pings from switch one or switch to router one.
There we go.
And then we'll go and do it from switch one ping 10 dot zero dot 10 dot 100. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And then we'll go and do it from switch one ping 10 dot zero dot 10 dot 100.
And there we go.
Switch one, campaign router one.
So again, the topology is really useful to us because it shows us exactly what
's happening
here and why these individual SVI's that we've created can communicate with
router one and
how we can leverage again those SVI's either for default gateways, which is
usually how
we use them, but also for troubleshooting because we might have a situation
where I need
to do some ping testing. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
to do some ping testing.
And so in this case, not only have I explored that topology, but I've also
created a router
on a stick topology, which again is is pretty legacy as far as the networking
world is concerned,
but it's also kind of a classic that now everyone's got a configure at some
point.
I hope this has been informative for you and I'd like to thank you for viewing.