- [Instructor] In this video,
we're going to configure OSPF Version 3
using a traditional approach,
and here's what I mean by a traditional approach.
We're going to have OSPF Version 2
and OSPF Version 3 running sort of in parallel,
side by side with one another.
OSPF Version 2 is already configured on these routers.
If I do a show IP route,
you can see that I've learned some OSPF routes.
So OSPF Version 2 is going to be used just for IPv4 routes,
and in parallel with that,
we're going to configure OSPF Version 3 to route IPv6 routes.
And I say that this is a traditional approach,
because we're going to see in an upcoming video
that there's another approach
called the address families approach.
And that approach let's us create
a single OSPF routing process,
and underneath that single process,
we create an address family for IPv4,
and we're going to get started here on R1.
Let's go into global configuration mode.
And the first thing we have to do
if we want to route IPv6 networks
is to enable a router to route IPv6 networks.
It's disabled by default.
To enable it, I'm going to say IPv6 unicast-routing.
And something else I like to do as a best practice
is enable Cisco Express 40 or CEF for IPv6.
This is not enabled by default,
and in fact, this command is not even supported
on some platforms.
You might want to check your platform
to see if it supports it,
but in general, I like to say IPv6 CEF
to enable Cisco Express 40 for IPv6.
Now let's create the OSPF routing process.
Instead of saying router OSPF and giving a process ID,
I pre-pinned that with IPv6.
So I'll say IPv6 router,
OSPF, and I'll give a process ID of one.
By the way, I happen to have used one
as as my process ID for OSPF Version 2 on this router.
That doesn't matter.
It doesn't conflict.
It doesn't have to be the same.
Those are independent.
I just used one, because it's easy to remember.
And for the same reason, I'm going to use one
on all the other routers in this topology.
Now let's set a router ID.
I'll say router-id, and to remind me
that this is R1, I'm going to give it an ID of 1.1.1.1.
Even though we're routing IPv6,
it still looks likes the router ID as an IPv4 address.
But remember, this is not some sort of address
that we're advertising.
We're not saying, "I'll get to you 1.1.1.1,
you can ping it."
No, this is just a label for this router.
Next, I'm going to create a passive interface,
because as we discussed previously,
interface gigabit 0/1, it doesn't connect
to another OSPF speaking router.
There's really no need for it to send
or receive OSPF packets.
So I'm going to make that a passive interface.
I'll say passive-interface
gigabit 0/1.
And if I give context sensitive help,
you'll notice that we do not have a network command
like we did with OSPF Version 2.
So how do we make an interface participate in this process,
and by that, I mean advertise that interface's network?
Well when we took a look at OSPF Version 2 configuration,
we saw that in addition to using the network command,
another way to make an interface participate
in OSPF was to go directly into the interface and say,
"Hey, I want you to participate in this process."
That's the way we have to do it with with OSPF Version 3.
So I'm going to go into interface gigabit 0/1,
and I'm going to say IPv6
OSPF process ID one area zero.
I'm telling this interface that I want its IPv6 network
to be advertised using OSPF process ID one,
and this interface is a member of area zero.
Let's go into interface gigabit 0/2,
and we'll give the very same command.
And we are done with our configuration on R1.
Let's go over to R2,
and we'll give a very similar configuration here.
Go in to global configuration mode.
I'll say IPv6 unicast-routing
to enable the routing of IPv6 networks.
As a best practice, I'll turn on
Cisco Express 40 for IPv6.
Let's create the OSPF process
IPv6 router OSPF process ID one.
Let's give it a router ID of 2.2.2.2 for router R2.
And now, there's no opportunity
for a passive interface here.
So now I'm going to go into my interfaces
and tell them to participate.
But notice, R2 is an ABR.
One interface is in area zero, one interface is in area one.
So we need to be careful with our configuration.
Let's go into interface gigabit 0/1,
it's in area zero, and I'll say IPv6 OSPF process ID one,
you're a member of area zero.
And for gigabit 0/2, oh notice,
we had an adjacency come up.
That's good news.
For interface gigabit 0/2,
I'm going to say IPv6 OSPF process ID one,
you're in area one.
And we're done on R2.
Next, let's go over to router R3.
Again, a very similar configuration.
I'll say IPv6,
unicast-routing, IPv6 CEF.
Let's create the process IPv6 router OSPF process ID one.
Let's give this a router ID of 3.3.3.3.
And here, we do have an opportunity to set
a passive interface for gigabit 0/2.
It doesn't connect out to any OSPF speaking routers.
So we'll say passive-interface gigabit 0/2.
Now let's go into each of our interfaces
and tell them to participate.
We'll say interface gigabit 0/1
and IPv6, OSPF process ID one,
you belong to area one.
We'll go into interface gigabit 0/2.
Oh, we had an adjacency.
Great.
I think we have all of our adjacencies set up now.
But under interface gigabit 0/2,
even though it's a passive interface,
I still want it to participate,
meaning I still want to advertise its network.
So I'll say the same command again,
I'll say IPv6 OSPF process ID one,
you're a member of area one,
and we're done with our configuration.
Now let's do some verification.
Let's go to router R2, there in the middle,
since it has a couple of neighbors,
and let's do a show IPv6 route.
We do that instead of show IP route.
And we can see that we have learned
a couple of routes via OSPF.
We've learned about the 2000:1::/64 route or network
that's hanging off of R1's gigabit 0/1 interface.
We've learned about 2000:4::/64,
that's connected off of gigabit 0/2 on R3.
So we've learned about those via OSPF.
Next up, let's examine the OSPF link-state database
for OSPF Version 3.
And since we're on R2 right now,
and R2 has a couple of link-state databases,
let's go over router R3,
because it's got a single link-state database.
I think that will make it a bit easier to interpret.
So let's go over to router R3.
And on router R3,
let's say show IPv6
OSPF
database.
And as we look through this,
we're going to see that we have some new LSA types,
and some things have been renamed a bit.
For example, we still have our type one,
our router link-states.
We still have our type two, the network link-states.
But the name of our type three LSAs has changed.
It used to be our summary LSAs,
and I was not a big fan of that,
because it implies that we're doing some sort
of address summarization, and that's not what we're doing.
So I much, much prefer the name
that OSPF Version 3 gives to type three LSAs.
Instead of calling them summary LSAs,
which I think is misleading,
it calls them inter-area prefixes.
Yeah, I think that's much better.
Inter-area prefix LSAs tells us, very clearly,
that we're learning prefixes from another area.
We've got a type eight called a link LSA
and a type nine called intra-area prefix LSAs.
Not the same as type threes, that was inter-area,
meaning between areas.
These type nines are intra-area,
meaning these stay within an area.
Let's talk about each one of these
beginning with the type eight LSAs.
These are the link LSAs.
These are used to advertise IPv6 link local addresses.
So on a single segment,
we're going to have type eight LSAs
letting our OSPF speaking devices know
about the link local addresses that are residing
on that segment.
And if we take a look, we have three type eight LSAs.
Does that make sense?
Should we have three type eight LSAs?
Let's consider R3.
It has a link between R2 and R3 that we know about.
Well, these LSAs are going to contain
the link local address for the outgoing interface on R3
and the other end of the link.
It's going to contain the link local address
for gigabit 0/2 on R2.
We're also going to have the link local address
of gigabit 0/2 on R3, but that's it.
There is no other link local address living
off of gigabit 0/2 on R3,
so we only expect to see three LSA type eights.
In fact, we can see the interface here.
We know about two of these type eight LSAs
off of gigabit 0/1.
That means the link local address
of both R2 and R3's interface on that link,
and we only have one on interface gigabit 0/2,
because there is no other device on that link
with a link local address.
That's why we have three.
And you might wonder, okay,
we have three link local addresses,
but what are those addresses?
We can pull back the curtain and actually see
what those link local addresses are by saying
show IP OSPF database link.
And this will give us more information.
And here we see detailed information about these three LSAs.
Here's one, here's one, and here's one.
And you'll notice within each of these,
we see the link local address being advertised by that LSA.
So we can actually see those addresses.
Next, let's consider those type nine LSAs.
Let me re-issue the command show IPv6 OSPF database.
Let's take a look at those type nine LSAs.
These are intra-area LSAs,
unlike type three LSAs, which were inter-area.
So this gives us information about networks
within an area.
Now that sounds a lot like the job of a type one
or a type two LSA, but as we're about to see,
type nine LSAs allows to peer into the actual prefix
that's being advertised.
Now in our example, we had these two type nine LSAs,
and we only have two, because there are only two links
in this area.
And if we have a segment with no neighbor
on that segment, for example, gigabit 0/2 on R3,
there's no neighbor on that segment.
So it's going to show up with a link ID of zero
representing that link.
So what's the advantage of a type nine LSA?
Well neither type one nor type two LSAs
let us see what prefix they represent,
but we can see that information with type nine LSAs.
Let's do a show IP OSPF database prefix command,
and we can see the actual prefixes
that are being advertised by these type nine LSAs.
Here's the prefix for that link between R2 and R3,
and here's the prefix for that link off
of R3's gigabit 0/2 interface.
So that's a look at how to configure OSPF Version 3
in parallel with OSPF Version 2.
OSPF Version 2 routing for IPv4 networks,
OSPF Version 3 routing for IPv6 networks.
Now in our next video, we want to take a look
at a different way of configuring OSPF Version 3.
It's using the address families approach.