That last troubleshooting lab was a lot of fun.
Let's do it again for Troubleshooting Lab number 2.
[MUSIC PLAYING]
So in this trouble ticket, and if you're
logged on from a computer to the CBT Nuggets website,
click on the link for the virtual lab, and let's
see if we can help solve the problem.
Here's what we've been told.
Looking at my notes.
The challenge we've been presented is that router 8
cannot see the routes that 5 is bringing to the table.
They are the 10.1.55.0, and 8, and 16, and 24-- WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
They are the 10.1.55.0, and 8, and 16, and 24--
all these networks.
They're being brought in by R5 to the network,
but they're not showing up on R8.
Has no reachability to them.
And then secondly, the challenge was that R7 cannot access R8.
So R7, if it pings to 192.168.1.8, it's not flying.
So that's the objective.
R7 to R8 and R8 sees the 10.1.55.x networks. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
R7 to R8 and R8 sees the 10.1.55.x networks.
And that's the 28- or 29-bit mask.
I think it's the 29-bit mask.
OK, so that's it.
So I'd encourage you to pause me right here
and go ahead and launch the virtual lab.
Give it a shot in troubleshooting.
There will be-- as part of this set of videos,
there will be at least one problem
injected as part of areas, then the type of area.
And then I've also injected a couple of little gotchas--
again, to keep us on our toes.
So happy labbing, and I'll see you back in a few moments, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So happy labbing, and I'll see you back in a few moments,
as we proceed with the walkthrough.
And as we proceed, I think what I'd
like to do first is just verify the conditions that exist.
So we'll go to R7.
And we'll do a trace to 192.168.1.8.
Yeah.
And we'll do a control shift 6 to stop that.
It's not going.
And then we'll also go from R8.
And here in R8, we'll do a show IP route. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And here in R8, we'll do a show IP route.
And we'll say just ospf learned routes.
And we are looking for 10.1.55, which is not here.
All right, so the challenge is which one do we
want to tackle first?
Let's tackle the fact that we cannot see the 10.1.55 networks
here on R8.
Now, well, let's go to the heart of the matter
and see whether or not R5 has those routes.
Because if he doesn't have the routes,
he can't redistribute them in. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
he can't redistribute them in.
So let's go to R5 and just do a quick check and take a look.
So we'll do a show IP ospf.
That's a good start.
And this says this is an autonomous system boundary
router.
Because it's doing redistribution
from external routes from static.
So that's great.
Let's see if it has any static routes.
Show IP route static.
Yep, there they are.
So from an OSPF perspective, it's
redistribute them into OSPF, these static routes.
But I didn't see them over on-- WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
But I didn't see them over on--
I didn't see them over on R8.
Well, let's see if we can go see them on a neighbor.
Let's go check on R7 and R3 and see if those--
Actually, you know what we could do?
Let's do this.
This will also work.
The external routes are going to be an LSA type 5.
And so we could just do a show IP ospf database and a question
mark and say external, and see if they're
in the link state database. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
in the link state database.
And they're not.
OK, so for some reason, they're not going in to the--
So this router, router 5, which owns
the routes, the static routes, and is redistributing them--
if they're not inside the link state database,
nobody in the area is going to have them.
So let's do a show IP ospf and take a look at the details
for this area.
So it said up here that he is earlier.
He is an autonomous system boundary router
because he's bringing extra routes in. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
because he's bringing extra routes in.
That's great.
If we scroll up a little bit more--
up too much-- his router ID is 5555.
And that looks fine.
And ospf process ID 1.
If we scroll down, there's the reference bandwidth, which
has been modified to 1,000.
That's fine.
Area 1.
We have four interfaces in Area 1.
You can see those with the show IP ospf interface brief.
Oh, this is a stub area.
That would explain why.
So a stub area does not allow LSA type 5s. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So a stub area does not allow LSA type 5s.
It's discriminatory.
It says no LSA type 5s.
So even if we have a router, an ASPR,
that's trying to bring in external routes,
they won't be allowed in the area
because the area is a stub area.
So that doesn't support it.
So to solve that, if we wanted the same benefits of a stub
area but we also wanted to allow routers in this area
to bring in the routes, we could bring them in as an LSA type 7
by simply making the area an NSSA area. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
by simply making the area an NSSA area.
So let's do that.
So I'm going to bring up-- let's verify real quick.
Yeah, this is a stub area.
And we have routes.
So let's just verify we have routes.
Show IP route ospf.
Oh.
Well, we don't have a lot of OSPF routes.
But we do have some.
And we can also do a show IP ospf neighbors.
And we have, it appears, full adjacencies with--
WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
OK.
We need to fix one problem at a time.
So this is showing that he has two neighbors based
on the IP address.
One's a dot 3 with a router ID of 3333 and one
at dot 7 with a router ID of 3333.
That basically says right there that R7
has the router ID of 3333.
That's going to cause havoc in this area, by the way.
So let's actually pause the LSA type 5s not coming in WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So let's actually pause the LSA type 5s not coming in
because of the stub area.
Let's go fix the router ID on R7.
So here on R7, we'll do a show IP ospf interface brief.
And that doesn't give us their router ID.
Show IP ospf.
All right.
So there it is.
And I think what I want to do here is--
in this lab, we don't have the option of doing a clear IP ospf
process.
So if we change the router ID, we
need to do that for it to take effect.
So let's do this. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So let's do this.
Let's just remove OSPF and put it back
on with the right router ID.
So no router ospf 1.
On.
And router ospf 1.
Router ID, we'll use 7777.
Now, it has a highest loopback address of 7777.
So it would take that anyway.
And then I hard put it here, just to be sure.
And then we'll do a network statement.
We'll say every single interface running
IPv4 is going to be an area--
let's take a look at our topology real quick-- WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
let's take a look at our topology real quick--
in area 1 right here.
Great.
So we'll put a 1 there.
And it's also an area 1 stub.
Because currently, it's a stub area.
And we should get a neighborship if I did everything correct.
Show IP ospf interface brief.
OK.
Yeah, it's coming.
So gig 2/0 is the one that goes up to R5. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So gig 2/0 is the one that goes up to R5.
And he sees the other neighbor out
there because of the count is.
So we do a show IP ospf neighbors.
We are still working on that.
So init, then 2A, then x start, exchange, and loading and full.
Oh, there we go.
Good.
So we're set.
We've got our neighborship.
If we do an up arrow key, show IP ospf neighbor.
All right.
OK.
Now, back to the problem of R5 not
being able to redistribute its routes. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
being able to redistribute its routes.
Let's do a show IP ospf back on R5.
it says-- if you scroll up a little bit--
it says it's an autonomous system boundary router.
But because it's a stub area, as it says down here,
LSA type 5s are not allowed.
So what we could do if we still wanted to redistribute,
we could make it not a special area.
You'd make it a normal area.
Or we could make it a not-so-stubby area, which
does allow redistribution, and they
would come in as LSA type 7s.
We've talked about those concepts in Encore WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We've talked about those concepts in Encore
and here in troubleshooting.
Let's-- as a plan, let's go ahead and make this area 1 not
a stub, but make it a-- not a stub area,
but a not-so-stubby area, which allows R5 to bring those routes
in.
So going back to the CLI.
I'll bring out one of my favorite tools.
Notepad.
Because we're going to do the same command on R3, R5, and R7
in area 1.
So config t.
And router ospf 1, no area 1 stub. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And router ospf 1, no area 1 stub.
And then area 1, not-so-stubby area.
And awesome.
That should do it.
And we just put that on all the routers
that are involved in area 1.
So we'll copy that--
make sure I copy that-- and go to area router 3,
paste it in, and router 5, paste it in, and router 7,
paste it in.
And give those a second to renegotiate. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And give those a second to renegotiate.
If we go back to R3 and we'll do a show IP ospf.
This now shows-- this is on router 3--
that this area 1 is an NSSA area.
Because it's an ABR, it's going to take these LSA type 7s,
convert them to LSA type 5s, before it
pushes those, or advertisers those, into the backbone.
That's all well and good.
So let's take a look and do a show IP route ospf.
And let's see whether or not we have-- there we go.
Look at that. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Look at that.
Woo-hoo.
Here's the external routes in the not-so-stubby area
that R5, with its redistribution,
is now bringing in.
So the problem was that R8 cannot see these routes.
So what should happen is this.
Here's the play-by-play.
If we go back to our topology--
a lot of moving parts here.
But here's the play-by-play.
What should happen is R5 brings the routes--
I'll change the color.
R5 brings those routes in.
They come in as LSA type 7s.
R3 sees those, converts them to LSA type 5s as it advertises WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
R3 sees those, converts them to LSA type 5s as it advertises
those into the backbone.
And then the other area border routers
are going to propagate the LSA type 5s into their normal areas
as well, so that R8 should be able to see it
if this is a normal area, and everything's working,
and we're not doing filtering of any type.
So let's check it out.
Let's get down to R8.
And on R8, hit the up arrow key.
Show IP route ospf.
Looking for 10.1.55. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Looking for 10.1.55.
I don't see it.
I see a lot of routes, though.
I mean, I see the--
I see the 10.1.7 route.
That's the route way down on the left hand
side of the network from R7.
But no, I don't see any external routes at all.
So what this should appear as to us is an external route.
So it's a NSSA route in area 1.
But once we look at it in the backbone--
let's see if we have it in the backbone.
Let's go to R2 in the backbone. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Let's go to R2 in the backbone.
Do a show IP route ospf.
Oh, look at that.
Right there.
So the backbone can see those.
So we're seeing them as external routes
because the LSA type 7 got converted into a type 5
at R3, as it said in the backbone.
But we're not seeing those routes over on R8.
WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Let's go back to R4 and see if R4 can see them,
which you should, because if R1 can see them,
R2, all the LSAs in an area are all synchronized,
so every router should be able to see those same routes that
are in the link state database for this area.
So let's go to R4, and let's just double check that.
So on R4, we'll do a show IP route ospf.
And there's the 55 networks.
Yep, sure enough. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Yep, sure enough.
But if we go to--
R8 did not see those.
Let's go to R6, the next hop in the path there.
And we know we have neighborships
because R8's seeing routes from the other side of the network.
And we wouldn't learn those without a neighborship with R6.
So let's go to R6 and see what R6 knows.
So on R6, show IP route ospf.
And sure enough, it doesn't know about those.
So it looks like all the routers that are only in area 2 do not WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So it looks like all the routers that are only in area 2 do not
have knowledge about those 10.1.55s.
Let's do a show IP--
but the neighborships are good because we're learning routes.
Show IP ospf, enter.
All right.
So in area 2, it's a step--
OK, well, that would explain it.
Stub areas are discriminatory against LSA type 5s.
So even though in this network here-- WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So even though in this network here--
get my pen out.
So even though there are LSA type 7s here,
as they got put in the backbone, now they're type 5s.
And R4, because this is a stub area over here, area 2,
it's not allowing the LSA type 5s to go into this area.
And that is why R8 can't see it.
So if it's really a requirement, which
it says it is, for R8 to see those routes, the 10.1.55
networks, we need to make this area no longer a stub.
So it can't be a stub.
And it cannot be a not-so-stubby because either one of those, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And it cannot be a not-so-stubby because either one of those,
with totally or not for either one of those,
they will not see the external network types.
So let's go to area 2, and we'll simply
say that it's not a stub area.
So we'll go to the command line.
And let's get out Notepad.
And we are going to say no area 2 stub, just
to make sure to take it off.
I believe that's what I need, actually.
Just no area 2 stub.
And that way, it'll be a normal area. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And that way, it'll be a normal area.
Control A, Control C. And then you have
to put it on the right router--
very important-- which would be R4.
It's the even routers going down that side of the network.
So R4, and 6, and 8.
And let's just go verify that on R4 for a moment.
So if we do a show IP ospf and press Enter,
here, it's showing that area 2 is
no longer a-- if it was a stub or not-so-stubby,
it would be showing that right here.
So it's just a normal area. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So it's just a normal area.
And on R8-- giving it a few moments to converge,
we'll do a show IP route for 10.
That's just all the 10 routes.
And there we go.
So there, we have the external type 2s
that were injected in the network
by the ASPR on the other side.
Wow.
OK.
All right, so that was one of our tasks.
Let me turn on my Notepad again.
OK, so R8 can now see the routes from R5.
Great. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Great.
And R7 can't ping R8.
That was the other challenge.
Let's go verify that that works or doesn't work.
So on R7, we'll do a trace out to 192.168.1.8,
which is the IP address, an IP address, on R8.
Oh, and that's flying.
Huh.
10.1.57. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
10.1.57.
5, 3, 1, 2, 4, 6, 8.
Oh, so we had fixed the router ID earlier.
Let me check one more thing, right here on R3 for a moment.
Actually, let's look at the routing table on R7.
Show IP route ospf.
Oh, so it has that specific route.
OK.
Because look at this.
This is an NSSA area.
So one thing about the not-so-stubby area WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So one thing about the not-so-stubby area
is that we don't get a default route by default.
So if we couldn't get to that address, what we would then
need to do is add a default route.
So I just want to demonstrate really quick that, by default,
this NSSA area at the area border router
does not inject a default route.
And we can see that right here on the routing table on R7.
So if we went back to R3, which is the area border router,
and we said area 1 NSSA space no dash summary, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
and we said area 1 NSSA space no dash summary,
which makes it a totally not-so-stubby area, that
injects the default route.
So stub areas, they get a default route by default.
Not-so-stubby areas don't get a default route
unless we make a totally not-so-stubby area.
So let's verify that here on R3 as well.
I think that'd be good to see in the lab.
So getting my mouse to the right place.
And we'll go to R3.
Config t, router ospf 1. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Config t, router ospf 1.
Area 1.
NSSA.
And here's how we do totally not-so-stubby area.
And there is no dash summary.
And that, with an NSSA area, is what causes
a default route to be injected.
So if we go down to R7, who didn't have a default
route just a moment ago, we give it a few seconds to converge,
do a show IP route for OSPF learned routes.
Check it out.
We now have a default route that was injected because it's WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We now have a default route that was injected because it's
a totally not-so-stubby area.
So just as a review on that.
The stubby area gets a default route by default.
A totally stubby area keeps the default route.
It's the not-so-stubby area that by default, doesn't
have a default route until you do
a totally not-so-stubby area.
So for more details on the area types,
and the functions, and the features,
please feel free to check out our content in Encore.
So in this video, we had some fun in troubleshooting OSPF
networks for IPv4, including some of the concepts regarding WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
networks for IPv4, including some of the concepts regarding
why a network may not function based on the area
types involved with stub areas, not-so-stubby areas,
normal areas, backbone areas, and so forth.
So in our next set, or grouping, of videos,
we're going to focus on area issues once again.
But we're going to do it for IPv6.
So I'll see you in that set of labs in just a few moments.
Meanwhile, I hope this has been informative for you.
And I'd like to thank you for viewing.