En route a to show ip ospf neighbor notice the neighbor relationship has changed to use the loopback
address of quadruple one.
So let's enable OSPF on router three to ensure full connectivity between all subnets.
Show IP interface brief will allow me to see the interfaces configured on this router and you can see
forced ethernet zero and the two serial interfaces serial 1/0 and serial 1/1 have IP addresses enabled
on them and the interfaces are up.
Let's configure a loopback for this router interface loopback zero.
IP address.
And they just make it quadruple.
Three.
Topping the command show, IP protocols will allow me to see that there are no protocols enabled on
this writer.
Once again, show IP protocols displays no output as no writing protocols are enabled.
Going into global config mode rather.
OSPF.
And I could use process ID three.
In this case, I'm using different process IDs just to prove the point that the process IDs are local
to the Rada and do not have to be the same across all routers in the real world.
It would make more sense to use the same process number on all of your routers if possible.
In other words, standardize on the process ID.
In this case, I could type the command network.
Ten .1.3.0.
And put in the wild card, moss.
As follows.
In other words, use the exact inverse of the network mask.
And as you can see here, a neighbor relationship was established between router three and router two.
I could use a command to show IP OSPF neighbors to see that that neighbor relationship has established.
I could then enable OSPF on serial one one.
So network ten .1.5.0.
With the wild card mosque, putting it into Area Zero.
And now a neighbor relationship has been established with router one.
So do show ip ospf neighbors shows me that on router three I have two neighbor relationships with router
one and with router two topping that come on network ten 140.
Will enable OSPF on the first Ethernet zero zero interface.
So now typing the command do show IP OSPF interface allows me to see that OSPF is enabled on the first
Ethernet zero zero interface.
The serial one one interface, 010 interface, but not on the loopback interface, even though OSPF
is not enabled in the loopback interface.
The Rada ID is set to the loopback IP address.
So lastly, I should do this network quadruple three exact match.
Area zero.
Not tapping the command.
Do show IP OSPF interface.
Allows me to see that OSPF is enabled on the loopback interface.
Going back to privilege mode, I can type the command show ip ospf neighbor to see my neighbors.
And once again, you can see router one and router two.
But I could also do this command show IP OSPF neighbor and specify an individual neighbor.
And this allows me to see more detailed information about the neighbor.
You can see that the neighbor with router id quadruple one and interface address ten 151 is connected
by a serial 1/1 and the neighbor relationship is full.
In other words, we are exchanging updates with one another.
Back on rata one.
You can see that the neighbor relationship with Rada three came up.
Break out of that.
And I can talk to him on show IP route.
And I can see that I've learnt about networks quadruple two, network quadruple three as well as network
ten 130 and Network ten 140.
Notice this gap means that we're doing load balancing because the costs are the same.
In other words, from rather ones point of view to get to network ten 130.
We could either use this link, which is 128 kilobits per second, or we could use this link, which
is also 128 kilobits per second.
So there are two possible paths to use to get to this network.
OSPF supports equal cost load balancing tapping the command show IP OSPF database.
Allows me to view the OSPF topology database and as you can see here for OSPF router with ID quadruple
one process ID one area zero.
We have learnt about three routers ourselves.
Router two and router three.
The number of links on router one is set to six.
The reason for that is a serial link as a link count of two.
Router one has two serial links 01/0 and serial 1/1.
In other words, two plus two equals four.
Router one also has a loopback interface, so plus one equals five and it has a fast ethernet zero zero
interface, so plus one equals six.
I can see that in more detail by typing the command show IP OSPF database and notice this option rather
and then specifying the router ID in this case ourselves.
And you can see once again that an area is zero.
Rada with Rada ID quadruple one has a stub network, which is a loopback interface with an IP address
of quadruple one and mask of slash 32 as well as a point to point link.
Connected to neighboring router quadruple three with local IP address ten 151.
In other words, this serial point to point link.
As well as Stub Network ten 150.
Slash 24.
In other words, the network on the serial link.
It's also connected to a quadruple T with local IP address.
Ten one, two, one.
In other words, this interface and on that interface we have network ten 120.
We are also connected to Network ten 110.
The two count those networks.
We have one, two, three, four.
Five six networks connected to router one notice.
On serial links, there are two entries.
The entry connected to the neighboring router on the point to point link as well as the actual subnet
on that point to point link.
So once again, show IP OSPF database shows me that for our local router we have six as the link count
because there are two entries for the serial links.
This is the topological database which is shared by all routers.
So on router to show ip ospf database.
Well, allow me to see that that router has the same information as Rada one.
It's the same database.
On Router three show IP OSPF database will allow me to see the exact same database link state routing
protocols shared the same database within the network or area.
These three routers on the same area.
So all three of them share the exact same database.
Back on router one, I could type the command debug.
IPOs, OSPF events.
To see event information on router one.