One of the stories that I've heard
that helped to understand the concept of VRFs
is a concept about a large room that two people are sharing.
Let's use Bob and Lois.
And Bob and Lois have their own personal stuff,
and if Bob and Lois are so concerned that they don't want
the other person to have their stuff, what we could do
is we could cut the room in half.
Well, it's still one room, but we could draw, like,
put a piece of tape on the ground or something
and just tell Bob, OK, Bob, all the stuff WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
and just tell Bob, OK, Bob, all the stuff
on this side of the room is yours
and everything on the right side of the room
is yours, Lois, and just keep your stuff separate.
And that's a logical separation of the room.
Half of it for Bob, half of it for Lois,
and we demark that with the tape.
Well, that's a lot like VRFs.
With virtual routing and forwarding instances,
instead of just having one giant room or one giant
routing table and all the interfaces
and all the IP addresses supporting that one
giant routing table, we can chop it up and carve it out.
So we could create one VRF for Bob with another VRF for Lois. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we could create one VRF for Bob with another VRF for Lois.
We can assign their appropriate interfaces, or their parts
of the room, to them, and then they can keep their own stuff
and it would be separate.
So a VRF is a logical routing table
that's isolated from the rest of the routing table
on that device.
And let me share with you an application where
covering up the routing table to keep routes separate
is very, very handy.
Check out this topology.
So here's the great application for VRF,
virtual routing forwarding instances.
This device right here, which is R4,
this is a service provider router. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
this is a service provider router.
Now, a router is a great thing.
It can route packets and so forth.
However, this router is learning routes from,
we'll call this in green, we'll call it customer green.
[AUDIO OUT] U-S-T green.
And he's also receiving routes from customer purple.
[AUDIO OUT] U-R-P-L-E. That's going to be a lot easier than
me saying customer 1 site 2 and customer 2 site 2.
I'll say customer green and customer purple.
So as those routes are being advertised into the router,
this service provider router needs
to keep those routes separate and isolated from each other WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
to keep those routes separate and isolated from each other
so here's what we could do.
We could create two different VRFs.
We could create one for green [AUDIO OUT] [INAUDIBLE] I call
the virtual routing and forwarding instance for green.
And another VRF [AUDIO OUT] four purple [AUDIO OUT]..
And then, on this router with this physical interface,
we can assign this interface right here,
[AUDIO OUT] one slash zero to that the VRF,
and assign this interface, gig two slash zero,
to the purple VRF.
And check this out, any routes that are learned on two zero, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And check this out, any routes that are learned on two zero,
the router will automatically assume,
OK, those routes just belong in this little mini me
version of the routing table called
VRF, the virtual routing forwarding instance
called purple.
And up here, it would be any routes coming
in from customer 2 would come in and they
would be associated with VRF green,
including the directly connected interface.
That's the concept of VRFs.
Now, VRFs are going to play a much bigger role
in something else that's also in this course called MPLS layer 3 WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
in something else that's also in this course called MPLS layer 3
VPNs.
But in this skill, I wanted to focus just
on the VRF portion of it.
Sometimes it's called VRF lite.
VRF lite is where you're using VRFs to segment
and separate routing tables.
In this case, we have two VRFs, two separate routing tables,
plus the global instance which is we often
call the default routing table that this router
is going to have.
So VRF lite is the concept of carving up and creating VRFs,
assigning interfaces to those VRFs,
but not necessarily using it in conjunction WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
but not necessarily using it in conjunction
with other technologies like layer 3 VPNs.
That's what we're referring to here as VRF lite.
So it's basically a three step process.
One, create the VRF.
And then there's a couple different ways
of doing that based on IPv4 only or using a method that supports
IPv4 and IPv6 address families.
I'll show you both of those in the upcoming videos here.
Secondly, we'd want to assign the associated interfaces
to those VRFs.
WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And then the third piece is, if we're adding routing protocols,
we'd do VRF specific routing protocols.
And I'll show you how to do that as well as we continue
through these videos together.
[AUDIO OUT] Another way, this one router, router 4,
if we want to run OSPF with customer green,
we can do it in association with the VRF of green
and it can interact and get the routes and updates WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
and it can interact and get the routes and updates
from the customer green.
Or down here, the purple customer,
if it's running red for EHERP or OSPF or whatever.
We can associate that routing process with that VRF.
And then as those routes are learned and communicated,
those it all be associated because it
coming in on this interface with the VRF called purple.
And that's how we can keep all that routing information
from our respective customers tucked away and isolated
in their respective VRF.
Now the other thing here, besides creating it, assigning WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Now the other thing here, besides creating it, assigning
interfaces, and setting off a routing protocol,
is the-- the other thing we also want to do
is become more familiar with show commands.
Because with doing show commands,
if we do a show IP route, by default,
that's going to show us the default
instance of our routing table, the global routing table.
If we want to see the routing table for a specific VRF,
we need to include VRF-related commands.
Or if we want to do a ping associated with a certain VRF,
we have to include that VRF name.
So as we proceed together and start getting into the configs WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So as we proceed together and start getting into the configs
starting with the very next video,
I'll walk you through how to both configure
and verify the VRFs once you have them set up.
So I'll see you in that next video in just a moment.
Meanwhile, I hope this has been informative for you
and I'd like to thank you for viewing.