[AUDIO LOGO]
So to start off, in this video, let's just
jump in and look at some of the major changes
between OSPF version two and OSPF version three.
Aside, of course, from the obvious that it supports
IPv6 which is our main reason for going to OSPF version
three.
However, it does have some other benefits and features as well.
So let's jump in and take a look at some of these changes.
And then through the rest of the videos,
we'll be looking at these in more detail.
But let's get started by just looking
at the major things that have changed between our two
versions of OSPF.
Probably one of the most important things
to remember about OSPF version three is that in many ways,
in fact, more ways than not, it is
the same as OSPF version two.
Now, it, of course, has some updated features,
not the least of which being it supports IPv6.
It runs over IPv6.
And since it does, in fact, run over IPv6,
clearly some things have had to change under the hood
as far as how OSPF version three operates.
But what we mean by this statement,
is things like the area types are still the same.
We still have stub, NSSA and so on.
Total stub, total NSSA.
All of the different area types are still supported
and they're still the same.
Virtual links are still fully supported.
They're still built between router IDs.
They're still used for the same reasons.
Now, here's, of course, a difference.
We still use multicast for our neighborships
but, of course, we're going to use IPv6 link local addresses.
Remember that in IPv6 any time you
see an FF in the address, that indicates that it's multicast.
And the 02 indicates that it's link local multicast.
This is very similar to what we had in IPv4
where the 224.0.0 was also link local.
So we're still using link local multicast,
and notice they even kept the last octet the same.
Five and six for our two groups.
And of course, we only use the .6
if there is a DR involved in the OSPF neighborships.
OSPF version three's originating RFC is 2740.
Of course, like all other protocols,
there are other RFCs that update it and add things to it.
But that's the fundamental RFC in case
you want to do any further research
and you enjoy just reading RFCs.
Now, as we indicated, the huge feature we're looking for here
is the IPv6 support.
And that of course, means it's going to support
128-bit IPv6 addresses.
It wouldn't be an IPv6 routing protocol if it didn't.
Next up, another difference is we can actually
have multiple OSPF version three processes
on a single interface.
So you can actually run multiple simultaneous instances
of OSPF version three on a single interface.
Not something we could do with OSPF version two.
Now the LSAs in OSPF version three
are expressed in prefix and prefix length
as opposed to the traditional address and mask
like we had in IPv4.
And this is just, again, a sort of a fundamental difference
between IPv6 and IPv4.
I really don't think you'd want to have to write out
a subnet mask for IPv6.
It would be something like, fff colon, fff colon.
It would just go on.
So yeah, we use slash notation for everything in IPv6.
And OSPF version three follows right along
and does the same thing.
Next, let's talk about the router ID.
Now, the router ID is a little bit interesting.
It is still a 32-bit number.
It has no relationship to any IPv6 address on the router.
Interesting point, if the router does
have an interface with an IPv6 address,
the router will, in fact, use that address as the router ID.
It follows the exact same method as it did in OSPF version two.
Meaning it will, of course, use a manually configured router ID
if one is set.
If there's not one configured manually,
it will then use the numerically highest IPv4 address
on any loopback interface.
And if there's none of those, it'll
fall back to an IPv4 address on any interface that's up, up
when the OSPF process starts.
That's exactly the same thing that OSPF version two does.
Where things get interesting with OSPF version three is
if it cannot obtain one automatically because maybe
this is an IPv6 only router.
Nobody says it even has to support IPv4.
So if it has no IPv4 interfaces, then you
have to set it manually.
You have no choice.
And just as a note.
Manual, just like in OSPF version two,
is really the recommended method by which
to set the router ID anyway.
So it really should be a moot point here.
We really shouldn't have to worry about any of this.
But just be aware that as you're putting the router ID in,
it is still a 32-bit number.
Keep that in mind.
Something else to keep in mind is
that our newest implementations can support both IPv4 and IPv6.
Now, they're still running on top of an IPv6 infrastructure.
So they're still going to be using
like IPv6 multicast addresses for communication and so on.
So you cannot run OSPF version three on an IPv4 only network.
But once it's running over our IPv6 network,
it can in fact, support IPv4.
Another interesting attribute about OSPF version three
is that it always uses the link local address of the neighbor
for the next hop.
What this really means is you don't actually
need global addresses on point to point links between routers.
Now, just so you know, there's a whole debate
whether you should still put global addresses
on the point to point links.
Say, maybe run /127s on your point to point links.
That's a debate for another time.
You don't actually need them.
You can just use link local addressing all the way
through your network core, for example.
However, it can also aid in things
like tracing paths through your network and things like that.
So again, a little bit of a discussion
you can have on that.
It's really up to you what you choose
to do in your environment.
Now, because of all the forwarding
that uses the link local addressing,
forwarding addresses would really make no sense in IPv6.
Therefore, OSPF version three does not
use forwarding addresses.
These don't exist anymore like they did in IPv4.
Some of the LSAs have changed as well.
We'll be looking at this in more detail in the next video.
But one of the things we do in OSPF version three is we
actually separate the topology information from the link state
information.
So the topology and the prefixes are actually separated.
We use the type one and type two LSAs
to carry the topology information.
Now, in OSPF version two, the type one and type two
had the topology as well.
But now it's only carrying the topology.
We take the prefix information and we break those
out into new LSAs that we'll be discussing in the next video.
For now, another change that's happened to the LSAs
is the type threes and fours have simply been renamed.
They still perform the same function.
But rather than being called summary LSAs and ASBR summary
LSAs, now we call them inter-area router LSAs
and inter-area prefix LSAs.
So it's just a matter of renaming them.
Which I think, for a lot of people, really
clarifies more what they're used for rather
than using the word summary.
Because summary implies like network summarization or route
summarization.
And that's not really what type three and type four LSAs
are for.
So I think they felt there was a little confusion there,
so they chose to rename them here in OSPF v3.
Personally, I think it was a good idea.
This name makes more sense.
Now, the last thing we want to do in this video
is just give you a quick introduction to the topology
that we're going to be using in this skill.
So you can see here, it's actually
very similar to the OSPF topology
that we've been using for our other videos
and our other skills.
However, now everything has IPv6 addressing
listed on our different links.
We have IPv6 addresses for our loopbacks
but we do still have different areas.
We have an area of 1,000 out here that's
not connected to area zero.
We'll be fixing that as we go through our videos.
So keep the OSPF V3 topology one handy
as we go through the rest of this skill.
So in this video, we just jumped in and got an introduction
to OSPF version three.
Some of the things that are the same with OSPF version
two such as area types.
In fact, things that we didn't mention,
like the way it does summarization,
is still the same.
We mentioned how it still supports virtual links.
And then, of course, we talked about some
of the things that are different.
Of course, it runs over IPv6.
So it uses IPv6 link local addressing.
Not only for the next hop, but it also
uses link local multicast for its neighborships.
So it does have a lot of differences under the hood.
But fundamentally keep in mind that at the end of the day,
this is still OSPF and it still overall functions
in the same way.
I hope this has been informative for you
and I'd like to thank you for viewing.