So our emphasis until now has been about building out the underlay for our T-
lock extension.
So we know we have edges 11 and 12 edit these remote sites.
We have a couple of transports in here with Biz internet and our MPLS and we've
got connections
to both of these from edges 11 and 12's perspective.
But then over here we have 13 connecting to the internet and 14 connecting to
MPLS.
And so what we've done now is we've extended the underlay as always on VPN zero
which is
where the underlay lives.
These are layer three links whether they're physical interfaces or sub
interfaces.
It doesn't matter.
We've chosen to use sub interfaces in our environment because we have a lack of
physical
interfaces left and so that's a good way to share a physical port but still
have different
logical layer three interfaces.
And now what we're trying to do is effectively make it so that if the internet
here is more
of a blue color then we see that we've got 11 12 and 13 all with T-locks facing
the internet.
But now edge 14 can have a T-lock for the internet.
And then we change colors here and we show the MPLS is the same concept where
at the
moment 11 12 and 14 all have T-locks facing the MPLS world.
But now edge 13 can as well.
And the idea here is that edge 13 will reach through edge 14 and edge 14 will
reach through
edge 13.
But we have yet to finish out this configuration because we still need to
configure the actual
T-lock extension.
Yes, this does require some explicit configuration.
But the steps for creating a T-lock extension is first of all to extend the
underlay.
And while we've talked about that we haven't yet done it and so we're going to
go do that
coming up here in the next video.
And then the second step is to configure the actual T-lock extension.
But why is explicit configuration required?
Why can't edge 14 just reach out now because this is part of the underlay and
reach out
through edge 13 and start to form tunnels with remote edge devices specifically
11 and 12.
Well, there's a pretty good reason for that.
And that is the fact that this interface here is that tunnel interface concept.
Recall what a tunnel interface is.
A tunnel interface allows us to block non-tunnel traffic.
And so I'm allowed to form a tunnel.
We have tunnels formed here.
11 has a tunnel coming into this interface.
12 has a tunnel coming into this interface.
We know 11 and 12 are forming tunnels as well.
But the fact of the matter is that if 12 then tries to form a tunnel through
this interface
to come down to edge 14, well, that's going to violate the fact that we're
trying to block
all non-tunnel traffic.
So that's part of the reason.
The other part of the reason has to do with advertisement and the fact that we
are using
T-locks, they get advertised as connection points.
Remember how this works.
We have somewhere in the environment, V-Smart or controller.
We've gone back and forth on what we call them.
We need to know both names.
But the V-Smart or the controller is sitting out here and it's running OMP.
And OMP is what advertises the T-locks.
So if edge 14 here wants to advertise its T-lock as saying, hey, this is part
of the
internet and specifically part of our Biz internet color, well, we're going to
want to
advertise this via OMP.
And then OMP is going to push this configuration down to the other edges so
they know how to
reach out.
And then we can form that connection.
So there's a lot more going on here than just underlay and pure layer three
routing.
Now it is important that we form this underlay traffic, but because of these
situations,
or specifically the way that we operate in an SD-WAN environment, we are going
to have
to configure a T-lock extension.
So let's talk about that.
What exactly is this extension concept?
Let's look at a generic edge here.
We could say that this is maybe edge 13 or it could be another edge with
different WAN
circuits, but either way, we know that we have a transport interface here,
which connects
us to something.
Maybe it's Biz internet, maybe it's MPLS, maybe it's from Metro Ethernet,
public internet,
any of these colors that we like to use to represent different types of
circuits.
And then we have this other interface down here that is going to connect to
another adjacent
edge.
This adjacent edge is going to try to form connections out through this
transport interface.
So how do we go about creating this T-lock extension config?
Well, the way it works is we're going to get onto this interface and alert it
to the fact
that it is forming a T-lock extension.
And specifically, it's forming a T-lock extension targeting this interface.
So we're going to, let's just say this is in our lab environment, it tends to
be gig
one, so it's a T-lock extension, gigabit ethernet one.
And by doing so, we're alerting the entire environment, and especially this
edge device,
the fact that it's going to allow for a T-lock to exist down here.
Because remember, we've got a T-lock here, which is an attachment point, and
now we have
a T-lock down here as well.
And so now we can form tunnel connections, and furthermore, tunnel connections
can come
in through that transport interface.
So that is generically how we're going to apply T-lock extensions into our
environment.
The question is, how do we do it in our lab environment?
So let's take a few moments to diagram this out.
What are we going to try to accomplish?
Well, first of all, we have a link here, and on both sides, that is gig four
dot thirteen.
And then we have a link over here, which is gig four dot fourteen.
As we've got drawn on here, the goal is for us to be able to reach out from
here, let's
try to get the right color, from edge thirteen, and then form connections
through the MPLS
cloud.
At this point, we'll have one, two, three, four T-locks in MPLS, and we're
going to use
gig four dot fourteen in order to do that.
So this is our MPLS link is gig four fourteen.
Meanwhile, we're going to do the same thing on the internet link.
We're going to create a T-lock down here and allow it to form connections this
way.
And then we once again can count, we see that we've got one, two, three, four
different
T-locks on Biz internet.
And so this would be our Biz internet color is going to be gig four dot
thirteen.
So what do we need to do on gig four dot thirteen?
We need to do two things.
First of all, I need to create the T-lock.
So that's number one, create the T-lock down here, T-lock.
And then number two, I'm going to need to create the T-lock extension.
And then same thing on the other side.
We're going to first of all, create the T-lock, and then we're going to create
the extension.
So notice which routers or which edges get the T-lock and which edges get the
extension.
So just depending on your level of familiarity with the lab environment, maybe
it's going
to be intuitive, maybe not, but let's just try to maybe jot down on a piece of
paper
next to our computers or at least get in our minds what gig four thirteen is,
which is
the Biz internet extension where edge fourteen has the T-lock and edge thirteen
has the T-lock
extension and then vice versa for gig four dot fourteen being the MPLS side of
things.
In the next video, we're going to start with step one and configure the T-lock
as well as
extending the underlay.
So I'm kind of including that as part of that, extending the underlay and then
we're
also adding in the T-lock configuration.
And then after that, we'll go in and configure the T-lock extension, also
explore kind of
how things are established and why we then need to configure the T-lock
extensions, which
is why we're breaking it up.
But let's go ahead and extend that underlay, make sure we've got good layer
three connectivity
Get the T-Lox configured.