In this video, you and I are going
to do a review of OSPF areas and their purposes.
So this is the topology we're going
to be using as we discuss and troubleshoot areas.
And with IPv6, the areas are very similar as they are
with OSPF version 2 for IPv4.
And that is, we have like normal areas.
This is the backbone area, area 0.
And then we have this area, which is
area 1 and this area, area 2.
And the rules for OSPF is that we WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And the rules for OSPF is that we
have to have every area that's not
the backbone needs to have an area border router that
logically connects that area to the backbone.
And so you can have dozens of areas,
but they all have to connect to the backbone.
So that's the concept of a normal area and the backbone
area.
We also have areas that can filter out external LSAs.
So let's go ahead and pick on R1.
If R1 is redistributing static routes, or some
of the routing protocol routes into OSPF,
those would be considered external routes. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
those would be considered external routes.
And they are going to be LSA type 5s.
And those LSAs get propagated through the entire domain.
If we want to tell area 1, hey, we don't want any LSA type 5s,
we have two options.
We could make it a not so stubby area,
or we could make it a stub area.
Both of those discriminate and do not
let LSA type 5s into the area.
And for a clarification, let me go ahead and let's do this.
Let me get my eraser out.
And let's imagine that here on the left
we've made this a not so stubby area. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
we've made this a not so stubby area.
And over here on the right, this is going to be a stub area.
Now, with the NSSA and the stub area,
they both are not going to allow LSA type 5s into the area.
However, the difference is that if this
is a not so stubby area, in a not so stubby area,
we can still do redistribution into OSPF.
But they come in as LSA type 7.
And then the area border router converts those to type 5s
as it sends them out of that not so stubby area.
Now, if we wanted to further reduce the number of routes
that these two areas, area 1 and 2,
had to work with, what we could do WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
had to work with, what we could do
is we could make them totally not so stubby, and totally
stubbed.
And what the totally in front of either of those terms does,
it tells the ABR not to take all the routes in the other areas
and send LSA type 3s into this area.
So it totally says don't bother sending the LSA type 3s.
It totally says, don't send the LSA type 3s,
with the exception they are both going to advertise an LSA type
3 default route into the area.
And another small difference with a stub and an NSSA, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And another small difference with a stub and an NSSA,
if they're totally stubbed and totally NSSA,
they both do default routes.
But if we had a stub area, not a totally stub area,
even just with the stub area, it still injects a default route
into this area regardless.
And where the NSSA, if it's not totally NSA
will not advertise the default route unless we
add that totally on there.
So that's an overview of the area types with OSPF.
It's the same game for OSPF version 2 for IPv4 and IPv6's
version of OSPF, which is OSPF version 3.
And in the next video, what I'd like to do WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And in the next video, what I'd like to do
is give you a chance to do a hands on lab
to go into this topology right here to get familiar with where
the addresses are.
I'll share them with you and how the routers are
adjacent with each other in a working network.
And then right after that, we'll go into a troubleshooting lab
and put you in the driver's seat to troubleshoot an IPV6 OSPF
network.
So I'll see you in the next video in just a moment.
Meanwhile, I hope this has been informative for you.
And I'd like to thank you for viewing.