Okay.
So here's the shot capture I faulted for OSPF.
We've got our two routers once again, this is rather one.
This is router two.
This is not an easy one to work out.
Let me start with rather two.
So if we look at right a T, we can see hello packet, we can see router ID, we can see and I'll just
move this up.
We can see password.
There's the password.
In the OSPF packet, we can see the subnet mask.
We don't see designated router backup designated router in the output.
We see data block.
Not too much here.
Extended twelves don't see too much.
That's interesting.
Let's see if we can see a difference on router one.
So router one backbone area and that's what's this is what's nice.
You can jump from one router to the other.
So this is rather one.
This is router two that looks right.
Simple password, right of one, router two that looks the same.
Authentication.
Same password.
Subnet mask looks the same.
Hello?
Interval.
Okay, here's something different.
Notice.
Hello.
Intervals.
10 seconds.
Hello.
Interval.
Here is 30 seconds.
If we look at.
Did interval date interval be 120 seconds.
The other right is 40 seconds.
Now, this is something in OSPF as well that you need to be careful of.
If the hollow interval is different, they're not going to form a neighbor relationship.
That interval is different.
They're not going to form a neighbor relationship.
If the two routers don't form a neighbor relationship, they won't exchange routes with one another
and routing will be broken.
If we have a look through the output here, we don't see any exchange of messages.
We only see hollow packets.
They will never form a neighbor relationship because the intervals are different.
So what I'll do is run the Wireshark capture again so you can see this in real time while I'm fixing
it.
So what we'll search for is OSPF we see both the routers advertising and if we look in the packet notice
we see a difference between hollow interval on the one router and the other router.
So router one has a 32nd hollow interval.
Router two has a 10/2 hollow interval.
That's not right.
Either the OSPF network type has been changed or hollow timers have been changed on the riders.
They are not the same.
This is Ethernet.
They should be the same.
So something's being changed either on the OSPF network type or.
On the hollow and dead intervals.
That's typically done on an interface.
So show run.
Interface gigabit.
Zero one.
Notice this option.
Here is the problem right away.
I know this because I've been working with OSPF for a long time.
You may not be aware of that.
But be careful in OSPF.
The network type has to be the same.
Another way to look at that is to type show IP OSPF interface.
And let me do a specific interface.
Okay.
Give it zero zero.
So show IP OSPF interface gigabit zero zero.
That's this interface on the right.
On the right show IP OSPF interface gigabit zero one.
That's this interface.
Notice what we see here.
We don't see that on the side.
We see priority.
We see DRT.
On the side.
We don't see.
D.R. That was another giveaway.
So if you go back to the Wireshark capture.
Notice.
On the one router router, one designated router and back up designated router are set to 0000, whereas
on the other router we have a designated rider.
Now there's no backup designated rider because Rider two sees itself as the designated rider.
But Rider one is not using a broadcast media.
It's set to point to multipoint so it doesn't go through an election process.
It doesn't take part in the election.
So there's no backup.
Designated Rider.
Rider two sees itself as the designated rider.
No backup designated rider, but rider one doesn't see either.
That is a giveaway straight away.
Apart from the timers, that tells you that there's a problem between these two riders now they don't
have to both use.
Port cos they could use point of multipoint.
But on Ethernet you want to use broad cos that's the default mechanism used.
You can see the network type right over there broadcast.
You can see over here network type point to multipoint.
They need to be the same.
Otherwise they're not going to form a neighbor relationship.
So show run interface gigabit zero one.
What I would do here is type IP OSPF network.
Notice the options.
I'm going to select broadcast.
So show run interface gigabit zero one again.
Notice Network is broadcast over there.
See the black in Wireshark neighbor relationship has been formed and the routers are starting to advertise
routes to one another.
So we know this is working just through the Wireshark captures.
But you can also see that on the consoles of the routers.
Notice neighbor relationships are formed to show IP.
OSPF Neighbor neighbor relationship is established between those two routers known as full BTR.
In other words, router one is the backup designated router on this side.
Show IP ospf neighbor.
Rather two is the designated rider.
This is looking at it from router one's point of view.
Show IP route routes have been advertised.
They are shown in the routing table.
So on the two PCs, they can now ping one another.
We've successfully resolved this network issue.
The hint or the thing to look out for was notice designated right.
A backup designator auto was zeros and the timers were different.
So if we scroll down to when the change was made notice, we see the timers as 10/2 on the one and 10/2
on the other.
It doesn't show us the designated backup designated order yet because it's still going through that
election.
But after a while we should see that notice.
D.
R btr.
Once they successfully elected and told each other about one another.
And then they.
Exchange rates with each other.
Okay, so I'll save this Wireshark capture.
I'll stop it here and then I'll save it as OSPF.
RT Is three fixed, so if you want to see what it actually looks like once it's working, there you
go.
Okay, so how are you doing with these troubleshooting videos and laps?
It's not that easy, but it's a real test of your networking knowledge and whether you can analyze packets
properly.