About 5 minutes ago and it executed three times.
So let's enable OSPF on router two and see how the output changes.
So on router to show IP interface brief will allow me to see the interfaces configured on this router.
And as you can see here, ten one two, two has been configured on 01/0 and ten 131 has been configured
on serial 1/1.
Let's configure a loopback on this router.
So interface loopback is zero ip address.
And let's configure this quadruple t tapping the command router OSPF two will enable OSPF on this router
with process ID two and in this case let's enable OSPF.
Using this format.
So obviously initially said just enable OSPF on all interfaces and let's put those interfaces in Area
zero.
As you can see here, a neighbor relationship or adjacency has been formed.
Neighbor ten 151 on serial 1/0 has gone from the loading state to the full state.
The full state means that there are those exchanging link state updates with one another.
This can get confusing.
Neighbor ten 151 is not directly connected to us.
IP Address ten 151 is not directly connected to router two.
However, that IP address is the router ID of router one and router two has formed a neighbor relationship
with router one and thus the router ID for router one is shown in the output, not the IP address of
serial one zero.
By the same token, on router one notice a neighbor relationship has been formed with quadruple two
on serial 1/0.
Notice that the process id on router one is one.
Whereas the process ID on router two is to process IDs are local to the writers and do not have to be
the same.
So I can top the command show IP OSPF interface and you can see that OSPF is enabled on the loopback
interface serial 1/1 interface serial 1/0 interface, which are the three interfaces configured on router
two going back to router one and topping the command show IP, OSPF will allow me to see that the SBF
algorithm has now been executed five times because new routes have been added to the topology show.
IP ospf.
Neighbor will allow me to see my OSPF neighbors router one at the moment only has a neighbor relationship
with router to notice the relationship is full.
Notice the dash.
The dash means that no election has taken place on this interface.
And the reason why is that it's a point to point link on a fast Ethernet network.
You would see various state share like D.R. for designated router, BTR for backup, designated router
and driver.
In other words, the neighbor is neither a D.R. or a BTR.
It's important to realize this command show IP OSPF neighbor is giving me information about my neighbor,
rather not about me.
In other words, neighbor with IP address quadruple two is connected to our local serial 1/0 interface
and the neighbors IP address on that interface is ten 122 on router to show IP OSPF neighbor.
Will allow me to see similar information for rather one notice.
Rather one's neighbor ID is ten 151.
Now, as per best practice, we should be using a loopback for the right ID rather than a physical interface.
So in router one, let's create a loopback interface.
And top the command do show IP OSPF interface and you'll notice that the router ID has remained the
same.
You'll also notice.
That the loopback interface is not in the list of interfaces.
And the reason for that is that we only enabled OSPF on specific interfaces.
So tapping the command do show run pipe section.
OSPF will allow me to see the configuration of OSPF in the running configuration.
And as you can see here, OSPF has not been enabled on the loopback interface.
So let's type router OSPF one network.
And let's specify a loopback address.
Now topping the command.
Do you show ip ospf interface?
Shows me that my router ID is still ten 151.
Let's type this.
Come on, clear ip ospf process and say yes to clear all OSPF processes.
As you can see, the neighbor relationship went down and then re-established.
So IP OSPF interface will show me that the router ID is still ten 151.
Now I could remove OSPF and re-enable it.
That's a bit of a blunt instrument to change the route id.
So I'm going to go to.
Rada ospf one.
Rada and then specify that Rada ID is quadruple one and notice what the Rada says.
Either reload or use the clear IP OSPF process command for this to take effect.
So let's type clear ip ospf process.
Say yes to clear all processes and see what happens.
Once again, the neighbor relationship went down and reestablished.
Topping the command show IP OSPF interface shows me that the router ID is now set to quadruple one on
router 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.