All right, my friend.
It's time for Troubleshooting Lab number 1.
In this Troubleshooting Lab, there's
going to be at least one, maybe more issues regarding something
about a OSPF areas.
So here's the lay of the land.
Area 0 is up here.
Area 1 here.
Area 2 over here.
Not using these links in this specific lab.
The network topology is 10.A for area number, 0, 1, and 2,
respectively, and RR are the two routers making up that number. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
respectively, and RR are the two routers making up that number.
So like 1 to 2 is 12, and so forth.
And the last octet is the router number.
Over here I have network 1, network 7, PCs on each.
And over here on this network, I've
got the 192.168.1 network with PC8 sitting right there.
So here's our mission should we choose to accept it.
We would very much love it if we could have full connectivity
from R7, which we could do from the PC
or R7 itself all the way across the optimum path, which WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
or R7 itself all the way across the optimum path, which
is this high road, not this low road, because it's
gigabit versus fast Ethernet, down to R8.
And R8's address is 192.168.1.8 right there.
So that's our objectives.
And have some fun with this.
Now, if you are not yet at a computer
where you can log on and do this,
you may want to pause me right now, because we don't
want to have a spoiler alert.
I'd like you to go ahead and try this and work on it,
and practice your skills in troubleshooting OS, including
anything related to areas.
And then once you're done practicing,
you can resume me or play me again. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
you can resume me or play me again.
And I'll walk through here in just a moment.
I'll walk through the solution to this Troubleshooting Lab.
So have some fun, everybody.
I'll be back in just a few moments for the walkthrough.
Here we go for the walkthrough.
Now, one of the benefits-- let me bring up the big screen.
One of the benefits of doing these labs
and building the Troubleshooting Labs a little bit separate
from me doing the walkthrough is that I've WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
from me doing the walkthrough is that I've
injected many different problems in many different labs.
And I'm not always sure or do I remember which
problems I put in which labs.
So some of this will be, oh, yeah,
I remember putting that there.
And other parts will be, what did I do again?
And that gives us a nice close to reality picture
of walking through this.
So let's go to the lab.
And let's solve this problem.
Let's start off at R7.
And that's the end of the network.
And we'll just do a ping to 192.168.1.8.
I want to verify that we can't get there. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I want to verify that we can't get there.
And if we can't get there--
yeah, we definitely can't get there.
So I'm going to do a Control-Shift-6.
And stop that madness.
Let's do a show ipv--
show ip route.
And let's do OSPF-learned routes.
Well, great.
So this is-- we have no OSFP-learned routes.
Let's make-- let's do a show ip ospf interface.
And I'll put a brief on there.
And it looks like we have our two gigabit interfaces enabled, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And it looks like we have our two gigabit interfaces enabled,
and our loopback 0 is not.
So it looks like we have our interfaces enabled for OSPF.
That's great.
If we do a show ip ospf, press Enter, and the router
ID is 7.7.7.7.
That looks fine.
And if we go down to the the area information,
there's no authentication setup.
We have three interfaces, including the loopback.
We just saw that a moment ago.
So it looks like our 7 may be OK. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So it looks like our 7 may be OK.
Let's go take a look at the next neighbor in the path--
and that is R5--
and see what's going on with him.
So back to R5 we go, or to R5 we go.
And let's do a show ip protocols just to make sure it's running.
So it's OSPF1.
Number of areas on this router, one normal area, meaning we
don't have a stub.
We don't have an NSSA.
We're in area 1.
It also shows here that we are learning from other devices,
including R7, R1, and R3. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
including R7, R1, and R3.
Although, look at the timer on that guy.
Let's do a-- let's take a look at the route.
Show ip route for OSPF-learned routes.
So the reason that this router thinks it's learning from R1
is because we have these external routes that
were injected by R1.
So R1 is an ASBR, an Autonomous System Boundary Router.
So it looks like OSPF, we just have a problem WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So it looks like OSPF, we just have a problem
with between R5 and R7.
Let's do a show ip ospf interface brief.
And let me take a look at my interfaces here.
So between R5 and R7, I've got gig 1/0 is the interface
that we're focused on that is facing down R7.
So 1/0.
It's in area 1.
That looks good.
It says it's a--
oh, look at this.
Curious.
So what this says is that the interface is a BDR. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So what this says is that the interface is a BDR.
But here it shows that we have one--
it sees one other OSPF speaker.
That's the C. But no full adjacency.
I wonder if that's just old information.
Let's do this.
I'm going to balance the interface.
Let's go into interface gig 1/0.
Let me confirm that's the right interface real quick.
And 1/0 right there.
Good.
And on 1/0, let's do a quick shutdown.
Give it a second.
A nice big breath.
Let's do a no shutdown. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Let's do a no shutdown.
Show ip ospf.
So OSPF version 3 is at play as well
for IPv6, which is a different discussion.
So show ip ospf interface brief.
So gig 1/0 is in a current state of waiting.
Let's go ahead and--
let me see if I can ping.
Ping to 10.1.57.7. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Ping to 10.1.57.7.
And show cdp.
I mean, show cdp neighbors is going to show--
oh, show cdp neighbors.
Why don't we see--
CDP happens every 60 seconds.
So let me just do a--
yeah, there's R7.
Great.
Because we pinged him, and so we can see him as well.
Same interface.
Let's do a show ip ospf, Enter.
Let's just do that real quick.
Process ID 1. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Process ID 1.
Router ID 5.5.5.5.
And down here, no authentication for
interfaces in the area, including the loopback.
Show ip ospf.
Oh, OK.
So currently it shows EXSTART.
So the neighbor states would go from init to 2A
to EXSTART, exchange, and then loading in full.
And it looks like they're not completing.
Let's go back to R7 and do a show ip ospf neighbor.
Oh, yeah.
Look at that. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Look at that.
EXSTART.
So this guy is stuck in EXSTART.
That's R7.
R5 is stuck in EXSTART.
So let's do some debugging.
Let's do a debug ip ospf.
And we could do--
if we also wanted to see timers and stuff,
we could do the hello messages.
But I just want to debug the adjacency.
And then we'll go back to the interface, interface gig 1/0.
Again, I'm going to confirm that interface
by looking at my notes here.
Yeah, 1/0.
And we're going to do a-- WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And we're going to do a--
oh!
I don't even need to.
Check this out.
This says that neighbor 7.7.7.7 has a larger interface MTU.
And that's why they're not going any further.
So let me turn off debug, undebug all.
Let's do a show ip interface for gig 1/0.
Now I remember.
The MTU doesn't match.
So the default MTU, let's go take a look at R7. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So the default MTU, let's go take a look at R7.
Show ip interface for gig 2/0.
Its MTU is 1,500 bytes.
And because they're off, that's part of the negotiation
that goes on.
And they have to match.
And they don't.
So back on R5, we could use the command Ignore MTU,
or we could just go ahead and say, take off that fake 1,480.
Let's do that.
Interface gig 1/0-- gig.
We need a spell checker for the CLI on Cisco. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We need a spell checker for the CLI on Cisco.
And then no ip mtu.
Show ip interface gig 1/0.
And now it's back to 1,500.
And let's see whether or not we get a neighborship.
Show ip ospf neighbor.
It looks much better.
So now we have a full adjacency with R7.
And if we get to R7, who a moment ago didn't
have any OSPF routes to speak of,
let's do a show ip route ospf. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
let's do a show ip route ospf.
Now we have lots and lots of routes.
Fantastic.
Let's do a ping back to the beginning of the show here.
Ping 192.168.1.8.
That's our goal.
That's failing.
Control-Shift-6.
And let's do a trace to 192.168.1.6.
See how far we get.
Oh, it's-- all right.
It's not even moving.
Let's do a Control-Shift-6.
So if we do a show ip route again for ospf on routes,
we're in a normal area. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
we're in a normal area.
And if we look through our routes,
we don't have the 192.168.
Let's go take a pot shot and see who does.
Let's go over to R4, the area border
router on the right-hand side that's connecting
the backbone to area 2.
Let's see if it has a route to 192.168.1.
And then we can work our way from there.
So going to R4, here we go.
On R4, show ip route, OSPF-learned routes.
Nope.
He didn't have it either. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
He didn't have it either.
Let's move down one further.
And that would be--
let's go down to R6.
I know R8 has that route, because it's
directly connected.
So let's go to R6 and see if it has the route.
So go down to R6, which is right here.
Show ip route ospf.
And it doesn't have it either.
Well, the only-- this implies that if R6 doesn't have that
route and R8 is advertising it-- we'll verify that if we need WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
route and R8 is advertising it-- we'll verify that if we need
to as well--
that perhaps it's a neighborship issue between R6 and R8.
We'll just show ip ospf interface brief.
And the interface we're looking for
is the one between R6 and R8, which is this guy right
here based on the IP address.
So fa 0/0.
R6 says it's the DR. We have-- we don't see anybody.
No count, no full adjacency.
Let's go take a look at R8 for a moment,
and make sure it's enabled for OSPF.
Show ip ospf interface brief. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Show ip ospf interface brief.
So this is the network between R6 and R8 right here.
It's the right network, fa 4/0 OSPF.
So R8 and R6 are not, for some reason, seeing each other.
They both say they're DRs.
They don't see each other on that same network segment.
And that's the segment right here between R6 and R8.
So why is that?
Well, let's troubleshoot.
Let's go back to the CLI. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Let's go back to the CLI.
And let's have a discussion with R8.
We'll do a show ip ospf.
Take a look at the area information.
So area 2, all of the interfaces are in area 2.
That's good.
And we'll go to R6.
Show ip ospf.
What?
Wait, wait, wait.
Oh, here's the problem.
There's your problem right there.
R6, if we look at the topology, shouldn't have any interfaces
whatsoever in area 1. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
whatsoever in area 1.
That's over here on the left.
It should have all of its interfaces in area 2.
That's where it's just internal to that area.
So let's go back and take a closer look at R6.
So for area 1-- this is on R6--
the number of interfaces in this area is 1.
Why is that?
Let's do a show ip protocols.
Here's our network statement.
0.0.
Oh, look at this.
So the network statement said, yeah, all IPv4 WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So the network statement said, yeah, all IPv4
interfaces in area 2, and then somebody explicitly
configured on an interface on fa 4/1
that it should be associated with area 1, which
is a mistake.
And that's why they're not neighboring up.
It's an area issue.
They do not agree on the area number.
R6 says this interface should be in area 1.
R8 says it should be in area 2.
And as a result, they don't agree.
And so let's fix that.
Let's go to config t, interface fa 4/0.
WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And we'll do a no ip ospf 1 area 1, because I think that's--
run a do show.
Oh, and there's our neighborship.
OK.
That was it.
Do show ip ospf.
So let's go back to R7.
And let's do a trace again to 192.168.1.8. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And let's do a trace again to 192.168.1.8.
Oh, and that looks good.
5 to 3 to 4 to 6 to 8.
Let's take a look at our topology.
So from R7's perspective-- let me bring my pen out here--
we are going from--
to 5 to 3.
Let me take a look at my notes again for a moment.
My notes meaning the output.
5, 3, 4, 6, 8. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
5, 3, 4, 6, 8.
So we have connectivity, but it is not the optimal path.
We need to take this path right here, which
implies that something is broken in this general area.
Either this is broken, or this, or this, or this.
And we need to go ahead and solve
that for the optimal path.
But I think we're getting closer.
I solved a couple of problems.
Let's take a look at the rest of it.
And let's go to R3 and just make sure we
have a neighborship with R1.
We'll work our way around the horn that way.
So over to R1 we go.
WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Show ip ospf neighbors.
Let's see if we have our neighborships.
So we have a-- well, we have a neighborship right there.
So R1 says it has a full adjacency with R3.
So that part looks good.
It also says it has a full adjacency with R2.
That looks good.
So that's this little leg of our journey right here.
Let's go over to R2 and see if it has an adjacency with R4,
because we know it has an adjacency with R1.
We just saw that from R1's perspective.
Let's go to R2 and check it out. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Let's go to R2 and check it out.
So here on R2--
I thought it, but I need to click it.
So here on R2, we'll do a show ip ospf neighbor.
Sure enough, we're missing our neighborship with R4.
So show ip ospf interface brief.
And I'm going to verify my interface here.
So on R2, it's gig 1/0 right here that is going down to R4.
So gig 1/0 is our concern for that neighborship. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So gig 1/0 is our concern for that neighborship.
And gig 1/0 is enabled.
So it says it's a DR. And it also says I see no neighbors,
and I'm not fully adjacent with anybody.
Let's verify we can ping to 10.0.24.4.
Yeah.
So why are we not--
so right here it's showing us it's
in area 0 from R2's perspective.
Let's go take a peek at R4. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Let's go take a peek at R4.
So on R4, it's going to be gig 2/0, which
is going to be our concern.
So on R4, we'll do a show ip ospf interface brief.
There's 2/0.
It says it's in area 0, which is correct.
It's a DR, because it doesn't see anybody else out there.
And it sees no other devices, speaking-- no other OSPF
speakers.
And it also does not have an adjacency. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And it also does not have an adjacency.
So why is that?
Here on R4, let's do a show ip ospf.
So there's no authentication.
Why isn't it peering up?
Let's take a look at that interface, which--
let's do a show ip ospf interface brief.
So again, these numbers here are really going to help us.
So this network here, the 24, is between the R2 and R4. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So this network here, the 24, is between the R2 and R4.
So let's do a show ip ospf interface for gig 2/0,
and see if there's anything funky going on there.
So it's up.
Attached via network statement.
Network type is broadcast.
It's a DR because it doesn't see anybody else there.
Default timers, it looks like.
I don't see anything weird there. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I don't see anything weird there.
Let's go look at the other side, which is R2's gig 1/0.
So on R2, we'll do a show ip ospf interface for gig 2/0.
OK.
Attached via network statement.
Process I-- router ID.
Network type BROADCAST.
What did I inject here?
Let's see here.
Oh, wrong interface, wrong interface. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Oh, wrong interface, wrong interface.
Dang.
Hold on a second.
Let's do a show ip ospf interface brief again.
I want gig 1/0.
Oh, I was looking at the wrong inter--
That interface looks so good.
Let's do a show ip ospf interface
for gig 1/0, which is the interface going down to R4.
Attached via network statement.
It's a network type of BROADCAST.
That's great.
What are we missing here? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
What are we missing here?
Hello and dead intervals look all great.
Oh!
Oh, here we go.
No hellos, passive interface.
So with passive interface, the router
will still include the network that it's directly
connected to on the passive interface as part of the OSPF
networks, but it will not send hellos or process hellos.
And that's why we don't have a neighborship between R2 and R4.
It's because this interface right here is passive.
So let's take that off.
Config t, router ospf 1. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Config t, router ospf 1.
No passive-interface for gig 1/0.
Oh, and there's our neighborship right there.
Passive-interface command.
Well, I'd forgotten I'd placed that passive interface
on that device.
Now we've troubleshoot three things.
Let's see if we have any more.
Go back to R7.
We'll do a trace to 192.168.1.8.
That looks great.
5 to 3 to 1 to 2 to 4 to 6 to 8. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
5 to 3 to 1 to 2 to 4 to 6 to 8.
And we have full connectivity.
Wow!
That was a little more difficult than I remember making it.
So in this Troubleshooting Lab, we indeed
did have some area problems injected
when we had two neighbors that didn't agree
on the area they were both connected
to for the common segment.
And of course, we also had some other challenges
to keep us on our toes.
So I hope you enjoy this lab.
I hope you did the hands-on practice,
and figuring it out, and troubleshooting
it step by step.
And I've got one other one that we're going to do right now.
And it's also going to have something involving areas.
And what we'll do is we'll inject those problems, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And what we'll do is we'll inject those problems,
or have those problems injected.
I'll also inject one or two other problems
to keep us on our toes.
So I'll see you in that next lab in just a moment.
Meanwhile, I hope this has been informative for you.
And I'd like to thank you for viewing.