So wrote a four show IP interface brief.
Can we ping router three?
Yes, we can show ip ospf interface.
OSPF is enabled on gigabit zero zero as well as the loopback interface.
So that looks good.
Are there any other problems?
It doesn't look like it.
So let's see if this is a problem with packet tracer or a problem with OSPF.
Interfaces configured in area two.
Let's have a look on the side show run.
Interface is configured in area to.
So what I'll do here is shut gigabit zero zero down and then no, shut it.
Interfaces come up, show IP OSPF neighbor.
We've got a neighbor relationship currently to router to.
Hopefully after a while we'll have a neighbor relationship.
To tend on 1.3.2, which is root of four.
We can ping that IP address.
Sometimes I find that in packet tracer, even though everything is configured right, you may have problems.
So here is another issue that I've encountered with Packet Tracer.
Notice this command is now missing from this interface.
So interface gigabit zero, slash zero.
I'll paste that command back.
So show IP OSPF interface.
OSPF is configured on the loopback interface.
It's configured on the gigabit zero zero interface.
Show IP OSPF neighbor.
Hopefully we should see a neighbor relationship come up.
But if that doesn't work, what I'm going to do is use the network command rather than the interface
command to kick start OSPF.
So rather ospf one network.
And I'll enable OSPF on all interfaces in Area two.
At the moment we still don't see a neighbor relationship here.
So when I enter that command.
Show IP OSPF neighbor.
Hopefully our OSPF neighbor relationship should come up.
Let's check if the same thing happened on the side.
Yes.
Notice the command was removed from this interface.
So let's put that back.
So interface gigabit.
Zero zero.
I'll paste that back.
And as you can see now, the relationship has now come up again.
So show ip ospf neighbor.
We have a neighbor relationship and we can ping the loopback of router for.
On Route one, we can ping the loopback of router four.
So for the real world, this shouldn't happen where commands are suddenly removed.
But that may happen in packet tracer.
It's a good lesson to learn, though, that when you make a change, just recheck things to verify that
things are still the way that you think they are.
So in this example, OSPF commands had been removed.
So ip ospf neighbor notice the neighbor relationship is now good.
So let me show you this on a real router.
This is a physical rudder running locally.
It's a 1941 router show.
IP Interface brief shows me a number of interfaces, including gigabit or zero one.
So show run interface gigabit is error one.
OSPF is not currently enabled on that interface, but if I go on to that interface and I type IP OSPF
one area to show run interface gigabit 0/1 notice OSPF is enabled on the interface in area two.
If I shut that interface down and do the show run again, notice the command is not removed even though
the interface has shut down packet trace added to that which is not correct when compared to a real
Cisco router.
Packet trace is fantastic software, but it's not perfect.
It's a simulator, so sometimes things don't work exactly as they would work on a real physical router.
But for this lab, we've been able to solve the problem.
Rather, one is learning about the loopback of router four and is able to ping the loopback of router
four.
I hope you found that useful and that you've learned some troubleshooting tips for the real world.