- [Narrator] You're probably already familiar
with the concept of VMs or virtual machines.
We get this big physical server.
We load up some sort of hypervisor on it,
like a VMware ESX eyes and example.
And on that one physical server,
we can install multiple virtual servers.
We can install a virtual instance of maybe some sort
of Linux machine at maybe Microsoft windows.
We can have all these virtual machines running on
one physical server.
What about a router though?
If we take a look at a physical router,
can we virtualize things inside of that physical router?
Actually yes,
we can have virtual routers running inside of
one physical router.
Let's say that we're a service provider as an example,
and we've got these different tenants.
We'll say we have tenants,
A, B and C,
and we want them to have their own routing tables.
We want them to be logically isolated from one another,
and we want to be able to route traffic for them,
but we don't want to have to buy a router
for every customer we have.
What we can do is set up something called VRF
or virtual routing and forwarding.
And we going to take a look at our next video
and how to configure that.
Now by the way,
we're specifically talking about VRF light here.
Light means that we're not using MPLS.
If you see the term VRF,
technically that means that we've got MPLS involved
and we don't.
And when you don't that's when it's technically called
VRF light.
However, a lot of people will use those terms
interchangeably a bit,
and they'll just generically call it VRF
whether we're using MPLS or not.
But I wanted you to understand the distinction
between those two terms,
if you were to see them in the literature.
But the cool thing we have here is isolation
between our different tenants.
We can even as an example,
have tenant A and tenant B
running the very same IP address space.
They could both be using the 10 dot address space
as an example.
And those would not conflict with one another
because they're logically separate.
We can have an IP writing table for each tenant.
And in addition to that,
we could even have an IP writing table
for the physical router itself.
And if we wanted to lead groats
into those virtual routing tables,
we could do that if we wanted,
but by default those would be isolated as well.
Now let's jump into our next video and see
how we could have different tenants,
all sharing the same physical router,
but appearing to have their own logical router
that doesn't have any influence from any
of the other routers
that are running on this physical router.