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[AUDIO LOGO]

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Next up, we are on
Trouble Ticket 2.

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We are still on MPLS Topology 3.

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And let's check out our ticket.

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OSPF routes on router 8--

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so we're talking about looking
at this router over here--

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from the customer
A headquarters--

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so this site over here--

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are showing up as OSPF E2
routes, or external type 2

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routes, as opposed to Interarea
routes, or O IA routes.

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So we're going to be looking
at the routes, of course, going

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from router 6 to router
8, as it specifies.

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And hopefully, we remember that
if OSPF routes are showing up

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as external, it's most likely
due to a domain ID problem.

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So let's jump in here and
see if we can figure our

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where the problem is.

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Again, we're probably going to
be focusing in on domain ID.

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So again, we always want to
start by verifying the trouble

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ticket.

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So let's just start with a
show ip route here on router 8.

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And we see that,
yes, in fact, we

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do have OSPF external
type 2s coming

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in for the routes on router 6.

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As we mentioned, this
is most likely due

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to a domain ID problem.

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So we might as well
start our investigation

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with the closest PE.

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Let's just hop over to
router 5 and see if we can

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get an idea of what's going on.

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So let's just start
with a show bgp

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vpnv4 unicast for
the vrf Customer A1.

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So we see here that we are,
in fact, getting the routes

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from the other side through
BGP, which, of course,

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we were pretty sure of, or the
routes wouldn't be showing up

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already.

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So what we really
want to do, of course,

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is look at more detail
on one of these prefixes.

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So let's go ahead and
repeat our command.

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And this time, add
the prefix 10.100.1.6.

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So if we take a look at the
details of this advertisement,

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again focusing in
on the domain ID,

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we see that the important
part of our domain ID

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is set to 64, which we
know is domain ID 100.

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And this is how we configured
all of this when we set it up

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originally in this course.

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So we could maybe
make the assumption

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that this is probably correct.

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But what we really care about is
not actually the number itself

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but whether it matches between
the different locations.

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So let's go ahead
and keep looking

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at some more information.

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Let's take a look
at a route that's

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coming in locally on this
side, which would be 10.8.

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So what we see here is on
this prefix, it doesn't match.

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This one is a 65, which, of
course, is the equivalent

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of 101 in decimal.

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So as we sort of
already suspected,

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clearly, the domain
IDs do not match.

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So this is the root
cause of the problem.

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But let's see if we can figure
out why they don't match

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and what's not
configured properly.

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Let's start here
with a show run.

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And we'll look at
the section OSPF.

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So here we can see
our problem already.

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We have router OSPF
101 for VRF customer A.

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And it's redistributing
BGP 100 subnets.

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However, there's no domain
ID specified, which means,

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on IOS XE, it's going
to use the OSPF process

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number, which is 101.

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We also see, even though we
weren't specifically looking

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for it, that customer A2s VRF,
which is OSPF process 102,

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is actually configured
the exact same way.

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So what we need to do here
is configure the domain ID.

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So let's go into configuration
mode into router OSPF 101.

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And we'll simply set the
domain ID to 0.0.0.100

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to match the other side.

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We'll do the same
thing for process 102.

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We'll exit configuration.

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And again, since this is a lab,
we can force this to refresh.

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We'll just do a clear
bgp vpnv4 unicast star.

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And we'll just let
this completely reset.

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We'll give this just
a moment to converge.

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And then we'll come
back and look at it.

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So now that we waited a few
moments, if we do our show bgp

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vpnv4 unicast for
the VRF customer A,

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looking at our local
prefix, again, this

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should now hopefully be updated.

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And we can see that
on both of our paths,

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both to router 8
and router 9, we see

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that the domain ID is 64 now.

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We already know that
that's the domain

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ID coming from the router 1
side, or the headquarters side.

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So that means that
they should now match.

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Let's go ahead and verify
the original ticket.

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Let's go out to router 8 and
take a look at those routes.

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So on router 8, we'll simply
do our show ip route again.

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And we see clearly that the
OSPF routes are now showing up

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as O IA, which is
what the ticket said

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was supposed to be done.

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So this is now fixed.

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So in this video, we saw
how OSPF routes passing

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through our layer
3 VPN environment

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will come out the other side
as external because, of course,

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they passed through
BGP in the middle.

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However, if our domain
IDs match on the two PEs,

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they will then come through
as O IA, or Interarea routes.

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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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