When we zoom out and take a look at what we've been trying to accomplish, we've
been trying
to build tunnels to build an overlay network that software defined wide area
network.
And so all of the configurations with T-Locks and underlay extensions, T-Lock
extensions,
it's all been for the purpose of getting us an overlay.
That overlay now looks very, very consistent.
We sort of drew this out early in an earlier video.
And now that I can connect 11 to 13 and 11 to 12 and 12 to 13, that was always
there.
But now I can also build from 12 to 14 and 11 to 14.
Now we start to see that the topology starts to mirror one another.
So my internet topology looks like this and my MPLS topology, I know the cloud
is down
there, but just kind of keep things roughly the same here.
It looks like this now, where we start to see that the topologies are identical
.
So if you kind of, in fact, let's just clear off the clouds, we don't need them
on there
anymore.
And there we go.
So now it looks a little bit more clear of what we've accomplished.
The yellow, or the yellow, the yellow devices, the red lines and the blue lines
are identical.
Our topologies are the same.
It doesn't matter what physically is connected where.
Again, we want to emphasize that point that the underlay is what we have and
what we have,
we can't change.
I mean, not without creating a change order and ordering a bunch of equipment,
but what
we have is what we have with the underlay.
The overlay, we have a lot more control over because we're simply building
tunnels and
the T-lock extensions allowed us to build tunnels, even though we don't have
physical
connections in some of these locations.
So now what we can do is we can look at the fact that I have a host over here,
over here,
there we go.
And that's the host I have highlighted here.
This is host 10-13 VPN 10 at site 13.
And it should be able to ping over here to a host that's in VPN 10 at site 11.
And down here, a host that's at site 12, but also in VPN 10.
So we're just going to zoom in to a single VPN VPN 10 specifically.
And now we can take a look at these different hosts.
So specifically, or for example, here, I should be able to ping over to those
other sites.
Remember, we can use the host name.
So like, for example, 10 dash 11, we start with 10.
And then we say 10 dot 11.
And then all of the hosts end in dot 50.
So we should be able to ping that host.
So now what we're doing is we're pinging this whoops, that didn't work.
Let's do it like this, that host, there we go.
We're pinging from 10 dot 13 to 10 dash 11 across this topology.
Now we know and recall that we have access through edge 13, which is the VRRP
master
and edge 14, which is the VRRP backup already demonstrated the failover that
exists if we
were to fail edge 13, it goes down.
But what we did notice before is if 13 lost its connectivity to the internet,
then all
of a sudden, our pings would stop.
So in theory now, we're hoping is that that is no longer the case.
So let's go ahead and flip over to edge 13 here, which is over here.
We got a lot of tabs open.
All right, so it should be this one.
Yes.
All right, so log into edge 13 here.
And I should just be able to get onto edge 13, get onto an interface.
So when we look at our topology, edge 13 has gigabit ethernet.
Oops, let's get interface in there.
And now gigabit ethernet one, this is our internet circuit.
So I'm going to do a shutdown on this link and do a commit.
And that's going to do quite a bit to edge 13.
It's going to lose access to its control devices as well, because that's the
only way
that it was able to talk to, for example, V bond and such.
And so we'll worry about that later.
But if we flip all the way back now to our device, notice we are still pinging.
Well, actually hold up.
I'm going to scroll all the way down.
There we go.
All right.
Now we actually see that it is pinging.
And so remember, when we tested this before, when edge 13's uplink went down,
we saw all
the pings stop.
And that's because edge 13 had no other way to send that traffic over to the
host that
is at either site 11 or site 12.
But now, even though these tunnels are both down from an edge 13 perspective,
it still
has these blue tunnels, the MPLS tunnels.
Physically, it has to send it over to 14 and then out a physical link.
But again, our focus is not on the physical now, is it?
It's on the logicals, on the tunnels.
And edge 13 absolutely still has a path to get to the other sites via the MPLS
circuit.
So this is exactly how we want to focus from an SD-WAN perspective.
Think about the fact that we're building overlays.
Think about the fact that those overlays exist independent of the underlay, as
long as we
have connectivity, then we can find connectivity.
Well, hey, then we're in pretty good shape, even if physical links start to go
down.