- Now let's take a look at the configuration of VRF,
and specifically this is VRF-lite
because we don't have an MPLS element,
but we're going to configure this VRF configuration
for a couple of different TENANTS.
Let's take a look at the topology that we have on screen
and see that we've got a couple of TENANTS,
we've got TENANT-A and we've got TENANT-B
and each of those tenants have a couple of switches
that connect into different router interfaces.
So let's begin by creating
a multiprotocol VRF routing instance for each TENANT.
And we want to specify the address family to be used,
specifically, we're going to be setting this up
for an IP version 4 address family.
What's going to global configuration mode on our common router,
we're assuming this is our physical router
that everybody connects into,
and I'm going to say VRF definition,
and I'll say TENANT-A, that's my routing instance
and I'm going to say address-family IP version 4.
Now let's create a VRF instance for our other TENANT,
I'll say VRF definition TENANT-B,
and again we use the same address family,
and now we want to assign each of our four interfaces
to an appropriate VRF instance.
We want to give them IP addresses
and administratively bring them up.
Let's begin with interface gigabit 0/1,
and I'll say VRF forwarding TENANT-A,
because if you look at the topology
that's TENANT-A's switch one.
Let's give it an IP address,
we'll say IP address 192.0.2.1 with a 24 bit subnet mask.
Let's administratively bring it up
with a no shutdown command.
Let's go into interface gigabit 0/2 now,
it also belongs to TNANT-A,
so we'll say VRF forwarding TENANT-A
and let's assign it an IP address
of 10.1.1.1 with a 24 bit subnet mask,
now we administratively bring it up with a no shut command,
we'll go into interface gigabit 0/3 now,
this belongs to TENANT-B,
so we'll say VRF forwarding at TENANT-B,
it's IP address is going to be and check this out,
it's an overlapping IP address,
it's the same IP address as TENANT-A has on gigabit 0/2,
is that a problem?
No, because they're logically isolated,
this is what I was mentioning in our previous video,
different TENANTS can have overlapping IP address bases.
I'll say IP address 10.1.1.1 with a 24 bit subnet mask,
if we were not using VRF,
we would get a big error message on the screen
saying no, no, no that's already in use,
but here they are logically separate.
Let's bring it up, I'll say no, shut one interface to go,
we've got another TENANT-B interface,
I'll say interface gigabit 0/4,
and let's say TENANT-B, it's IP address
is going to be 198.51.100.1 with a 24 bit subnet mask,
let's administratively bring it up,
and we're done that's how we configure VRF
for two different tenants,
and we assigned a couple of interfaces for each TENANT.
Let's do some verification though,
let's first verify the VRF instances
that are created on the router.
I'm going to do a show IP VRF,
and we see those two instances, TENANT-A and TENANT-B,
along with the interfaces belonging to each TENANT.
Let's now take a look at the IP routing table
for each of our instances.
First, let's take a look at the routing table
for TENANT-A I'll say show IP route,
but I'm not going to stop there,
I'll say VRF TENANT-A
and it knows about those directly connected networks.
The C says these are directly connected networks,
the L that's the local IP address,
that's the interface IP address for those networks,
so notice they don't see any of the interfaces from TENANT-B
let's take a look at TENANT-B's IP routing table,
and remember we did have an overlapping IP address 10.1.1.1,
but that's okay,
this is a different instance of 10.1.1.1,
it's not overlapping with what TENANT-A has,
and the router itself, not one of the instances,
but the router itself,
it can have its own global routing table,
that's independent from the VRF routing tables,
to show that let's create a loopback interface
and let's let it's route live in the global routing table,
let's go back into global configuration mode
and let's say interface loopback zero,
and I'll give it an IP address of 5.5.5.5
with a 32 bits subnet mask,
and let's see if that 5.5.5.5/32 lives
in the global routing table,
I'll say show IP route
and notice we only see that interface,
we're not seeing routes from any of our VRFs,
but can the VRFs see what's in the global routing table?
What's do a show IP route VRF for TENANT-A,
no, it has no knowledge of that 5.5.5.5/32 network,
what about TENANT-B?
It doesn't either, so we have isolation,
right now we have three different routing tables,
one global routing table,
and one for each of our TENANTS that are isolated
from one another even though they're all running
on the same router.
Now, if we want to,
there is an option where we could leak specific routes
between our global routing table and our VRF routing tables,
If we wanted to do that, we would use our route map
to specify what we wanted to quote and quote,
leak into a VRF table,
but that's a look at how we can configure VRF-lite.