When we look at our lab environment, we're going to build out edges 13 and 14
using the
T-LAC extension concept.
What we have is we have effectively an internet circuit coming into 13 and an
MPLS circuit
coming into 14, and we want to be able to build tunnels for 14 to go out to the
internet
and form tunnels and for 13 to go out to the MPLS and build tunnels, sort of
like this.
Keep in mind that Edge 14 does have a circuit to the internet, but this is just
so it can
reach V-Manage and V-Smart or Manager and Controller.
All of our control components are upstream of that.
So when we're really talking about forming data plane tunnels, this is our top
ology.
Now we do have a problem here, which is that we only have one interface
available on Edge
14 because of that, because both Edge 13 and 14 have the VPN 10 local area
network
connection, and that's pointing out Gig 3.
So Gig 1, Gig 2 are occupied, Gig 3 is being used for our LAN, which means that
we really
only have one more interface, which is Gig 4.
And so that's well and good, except we want to build out a connection, really,
from 13
to 14 for our T-LAC extension one way, and from 14 to 13 for the other T-LAC
extension,
and yet we only have a single physical interface for this.
So how are we going to do this?
Well, we're going to take advantage of sub-interfaces once again.
Sub-interfaces are going to use .1Q tagging, so .1Q, basically V-Land tagging,
and from
there we're going to build logical layer 3 interfaces rather than physical ones
.
So physically we're going to have Gig 4, let's just draw a physical up here, so
the physical
drawing is going to be Gig 4 and Gig 4, and they're going to connect to a
single layer
2 switch.
This is going to be an iOS V-L2 switch, which is a type of iOS switch that's in
CML.
This iOS version of a layer 2 switch is going to be capable of V-Land, which is
why we can't
use the unmanaged switch like we've been using, because we're going to need
multiple layer
2 domains.
And the reason for that is because physically we have a single interface, but
what's happening
logically?
Well, logically we're going to have two connections.
We're going to have a Gig 4, except we're going to put a .on there and call
this Gig
4.13, and there's a Gig 4.13 down here, and it's going to connect logically to
one another
through this physical topology, but logically we're going to have a 10.13.13.0/
30 subnet
with .1 being edge 13 and .2 being edge 14.
And then we're going to do this again, this time with a different logical sub
interface.
And these are going to connect to each other like so.
This is going to be Gig 4.14, and once again we'll have .1 and .2 addressing.
So 13 is always going to be .1, 14 is always going to be .2, and we're going to
have 10.14.14.0/30.
Now think about what we had talked about just in the previous video.
We need to think about things from a routing perspective.
If, for example, Gig 13 is supposed to form tunnels out this interface going to
the MPLS
world, then the MPLS world needs to know about this subnet.
And likewise, if our Gig or our edge 14 is going to form tunnels out this Gig 4
.14 interface,
then not the internet per se, but the devices that are attached to the internet
need to
know where this subnet lives.
So just to kind of diagram that real quick, we need to know on the internet
where 10.14.14.0/30,
we need to know where that is.
And the MPLS is going to need to know how to get to 10.13.13.0/30.
Where is that?
Now as we mentioned in our lab environment, we're just going to do this with
static routing.
So I'm going to get on to the devices, edges 11 and 12 are the only ones that
aren't part
of this site, right?
On to edges 11 and 12 and configure some static routes so that they know where
these
other subnets are.
They need to specifically know which transport to use as well.
So if edge 11 is out here and we tell it, hey, this is where, you know, subnet
10.13.13.0
is, if we say, oh, well, actually just slash 30.
So here's where this subnet is, but we have to tell it which transport is it
connecting
to?
So if we're using 10.13.13.0 to connect out MPLS, well, then we need to let it
know that
it's directing towards MPLS.
So this is how we're going to build this out in such that we can form tunnels
out the appropriate
interfaces on all of these different edge devices.
So some of them are going to need default routes 11 and 12 will need to have
default
routes to our extension subnets.
But we're not quite done yet when we talk about default routes.
And the reason for that is because remember, edge 14 here does have this
internet connection.
Furthermore, it's part of VPN zero.
And so edge 14 knows already where the internet subnet is.
And so we need a static route that points to edge 11 and edge 12 as far as
being out
the directly attached link, because this is a slash 24.
And remember, we're trying to get to, let's say this interface that edge 11 has
out here.
Well, by default, edge 14 will try to build a tunnel this way.
Instead, we're going to do specific slash 32 routes that tell edge 14 to go
this direction.
So as you're taking notes, really what this comes down to is us talking about
inbound
and outbound.
Every single time we build out a topology, whether in a lab or in real life, we
need
to make sure that the tunnel can properly come inbound, namely, how do these
devices
know how to get to a specific subnet, but then outbound as well.
How is edge 14 going to try to get to edge 11?
The internet in our environment, which is again, is a fake internet, is 192.168
.255.0.
And that's a slash 24 subnet.
So if that is a directly attached subnet, then edge 14 is going to try to use
that to
form the tunnel to edge 11 out the internet.
And that's not what we want at all.
We want this connection to only be used with the appropriate T lock.
And yes, we are, we do remember.
We put this in the red T lock color, but that's not going to affect the
underlying routing.
It's just going to tell edge 14 that it's really not allowed to form T lock
tunnels out
that interface, at least not to non-red types of tunnels connections.
So this is why a static route pointing to these devices going out this link and
then
creating a T lock that is part of the correct color is going to allow to
properly form tunnels.
So this is what we need to do.
We have our plan in place.
Let's go ahead and make it happen.