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So now it's time to talk about
bringing the ultimate summary

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route into OSPF,
the default route.

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Because that is a summary
of all other routes.

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That's what a default is.

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Now back in our skill on
OSPF special area types,

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we've already
discussed some ways

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that a default comes into OSPF.

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A stub area, for example,
always generates a default,

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as does a total stub
and a total NSSA.

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Now, an NSSA can also
originate a default route,

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but we have to do that manually.

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Well, the way we do
it in a normal area

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is also very similar to the way
we do it in that normal NSSA.

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And that's what we're going to
be focusing on in this video.

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how do we bring a default
route into OSPF other

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than our special area types?

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So let's jump to our
topology real quick,

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just to take a look at where
we're going to bring it in.

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And then we'll jump on
to the command line,

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and we'll see this in action.

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So very simply, in
this case, we're just

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going to bring in a
default route on router 10,

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have it inject it into the
rest of the OSPF environment.

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Now as we jump into
this, keep in mind

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that currently, router 10
does not have its own default

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route going anywhere.

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So that's just something we
need to keep in mind as we

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jump into the command line.

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So since we know there's
no defaults anywhere

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at this point,
there's nothing really

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to look at before we begin.

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So let's just jump right into
the command line on router 10.

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So what we'll do
here on router 10 is,

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under the router
OSPF process, we

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will use the default
information originate command.

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We'll hit Enter.

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And this is supposed to
inject a default into OSPF.

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Let's just jump right over
to router 6 to see if it has.

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If we do a show
IP route OSPF, we

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see that there is
no default route.

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The reason we're not getting
this default route here

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on router 6 is because in order
for the default information

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originate command to
actually send in a default,

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the router doing the default
information originate

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has to have its
own default route.

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And in this case,
router 10 does not.

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Therefore, default
information originate

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is not doing anything.

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In order to get it to work,
we really have two choices.

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Choice number one is, we can
simply give router 10 a default

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route, in which case
that'll meet the criteria,

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and router 10 will start sending
a default route into OSPF.

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And we'll do that option first.

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But in some
situations, you may not

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want router 10 to
have a default route.

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Or maybe for some reason,
it can't, in which case

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there's an additional option
on the default information

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originate command that we can
use to tell it to originate

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that default, even if that
router itself does not

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have its own default route.

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So we'll take a look
at that option second.

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But let's start by putting a
default route onto router 10.

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So back up here on
router 10, we will simply

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make up a default route.

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We'll just say that it's
going to route the default

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to say loopback 0, which
of course, is not really

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a valid default gateway.

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And it's sort of telling us that
here as well in the message.

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But that's OK.

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If we do a show IP route, it
did, in fact, still take it.

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So even though it's, of
course, really not valid,

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that's not going to matter
a whole lot to OSPF.

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Let's go take a look
at router 6 again.

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On router 6, if we look
at our route again,

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we see that we are now, in fact,
getting that external type 2

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default from router 10.

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So another important
thing to note here

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is that default information
originate brings that default

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route in as an external type 2.

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Now this default
should be propagating

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through our entire OSPF domain.

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So let's just pick another
router, such as router 4,

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to verify.

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So on router 4, we'll
do a show IP route.

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And we see that
this router also has

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that default equals now that's
being originated into OSPF.

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So now let's look at
the second option.

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Let's go back to router 10.

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We will take out that
default route we just put in.

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We'll go back into the
router OSPF process.

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And on the default
information originate command,

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we will say always.

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Notice, by the way, there
are some other options here,

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which we're not
going to explore.

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But we could, if we wanted
to, manually set a metric

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or change the metric type.

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So if we wanted this to be, say,
for example, an external type

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1, we could change that.

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Or we can also run this
through a route map

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to change various
attributes of the route.

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In this case, we're just going
to go ahead and say always.

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So now, if we do a show IP
route on router 10, notice,

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it no longer has
a default route.

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However, if we go back
to, say router 6 again,

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we look at our
routing table again,

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we still have a
default. And again,

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It should be propagated
through the entire domain.

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We could verify
again on router 4.

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We'll do the show IP route
here on router 4 again.

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And we can see that
we do, in fact, still

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have this default route.

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In this video, we looked at
originating a default route

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into OSPF, specifically
using the default

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information originate command.

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Our key takeaways here
would be that if you just

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say default information
originate by itself,

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there is a requirement
that router already

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have its own default route
in its routing table.

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If you cannot or do not want
to supply that router with

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a default route, then you
can add the keyword always

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to the default
information originate,

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and it will always
generate a default route,

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even if that router itself does
not have a separate default.

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I hope this has been
informative for you,

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and I'd like to thank
you for viewing.

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