So he our sample network.
We have router one with IP address ten 111 on Fost Ethernet zero zero ten 1211010 which is connected
to our two or two is configured with ten 122 on 010 and ten 131 on serial one.
One or three is configured with ten 1321010 and ten 141 on FOSS Ethernet zero zero or one and all three
are connected via another serial link and are configured with addresses ten 151, one or one and ten
152 on are three.
Please note that the link speed of the serial links have been set to 128 kilobits per second.
Songwriter one.
So run interface serial 1/0 will allow us to see the configuration and see it's got an IP address and
the bandwidth has been configured to 128 kilobits per second.
The same information can be viewed on serial one one IP address with bandwidth.
Show IP protocols will allow me to see that no writing protocols have been enabled on this writer.
So going to global configuration mode, I can now enable OSPF by tapping the command router OSPF and
specifying a process id once again, this process ID is local to the router and does not have to be
the same on all of the routers.
So on router one, I'm going to specify one.
Popping the command do show IP protocols will allow me to see which routing protocols are enabled.
And as you can see here, OSPF is enabled with process ID one and the router ID is set to ten 151.
However.
Topping the commands do show IP OSPF interfaces will allow me to see that OSPF is not enabled on any
interfaces on this router.
OSPF will not form neighbor relationships and will not exchange routes.
For neighbor relationships to be established and for routes to be advertised, you need to top the command
network.
And then specify a network so I could specify ten .1.1.1 the IP address of the Fost Ethernet zero zero
interface.
And then I can specify a wildcard mosque.
This is an inverse mosque similar to an access list with zero in binary means match and one in binary
means ignore.
So this is an exact match on that IP address.
OSPF will only be enabled on fast ethernet zero zero.
You then need to specify an area.
And in this case, I'm going to specify area zero.
The area can be specified as a decimal value in this range or in dotted decimal IP address format.
We're just going to specify the area as area zero.
Now typing the come on do show IP OSPF interface allows me to see that OSPF is enabled on fast Ethernet
zero zero.
The IP address on that interface is ten 111 slash 24.
And the area that that interface is being put into is area zero.
You can see once again that the process ID is one, the router ID is ten 151 and the network type is
broadcast.
Because fast ethernet zero zero is Ethernet.
OSPF will see this as a broadcast media.
The cost is one.
Once again, referring back to the OSPF formula, a 100 meg link will have a cost of one.
Notice the priority is set to one, which is the default.
There is no designated route on this network.
The hello interval is 10 seconds.
The date interval is 40 seconds, so a lot of information can be gathered just through the single command.
Tapping the command again.
Notice we have become the designated Rada.
Al Rata ID is ten 151 and the designated writer ID is ten 151.
In other words, it's us.
Notice the interface IP address is ten 111, which is the IP address and the Fost Ethernet interface.
On Ethernet.
As explained, routers will go through an election to determine the designated router and backup designated
router, and that election has now taken place with our local router becoming the designated router
because there is no other router on this segment.
So we are the de facto designated router.
OSPF, however, has not been enabled on the serial 1/0 interface and serial 1/1 interface.
So let's do that.
Now I can type the command network ten .1. 2 to 1, the IP address of serial 1/0.
Once again put in my wildcard mask once again put in my area.
Now topping the command show IP OSPF interface allows me to see that OSPF is enabled on serial 1/0 as
well as fast Ethernet 0/0 hitting spacebar.
Shows me that OSPF is not enabled on any other interfaces.
So once again, network.
Ten .1.5.1.
Wild Card mosque and our area will enable OSPF on the serial one one interface.
Show IP OSPF interface shows me that OSPF is now enabled on 011010 as well as Fast Ethernet zero zero.
Doing that.
Come on again.
It allows me to see information relating to the serial interfaces.
Notice that on both serial interfaces the process ID is one.
As you would expect, the router ID is ten 151.
As you would expect.
The network type, however, is point to point.
OSPF is intelligent enough to realize that this is a point to point link and thus the OSPF type is set
to zero point to point.
Notice the cost is 781, which is the cost of 128 kilobits per second link.
Once again, the hollow interval is 10 seconds, the date interval is 40 seconds.
But what you won't see here is designated router and backup designated router.
There is no need for an election on a point to point link because there are only two routers communicating
with each other.
So no election has taken place.
So just to give you the full syntax of commands control z, show ip ospf.
Interface.
Shows me the interfaces that OSPF is enabled on.
Show IP protocols will allow me to see the routing protocols enabled on this router.
And as you can see here, OSPF one has been enabled.
The router ID for the local route is ten 151.
The number of areas configured on this router is one with one normal area, no stub areas and no not
so stubby areas.
Stubborn, not so stubby areas are special types of OSPF areas used to reduce the number of routes in
the routing table.
The maximum number of paths that we will load balance across by default is four, but that could be
changed to 16.
We are routing for the following networks ten 111 ten 121 ten 151 Notice the masks we have specified
the individual IP addresses when we entered the network command.
The reference bandwidth is 100 megabits per second, which is the default.
The administrative distance of OSPF is 110 tapping the command show IP route.
Shows me that I only have directly connected routes in my routing table.
The reason why is we have not enabled OSPF on router two and router three, so we are not receiving
routes from either of those routers.
I can talk to command show IP OSPF.
Which gives me a lot of information relating to the OSPF process running on this router.
Once again, process one is being enabled.
The router ID is ten 151.
We can see timers and statistics like this.
For instance, initial SBF scheduled delay 5000 milliseconds.
The router will wait 5 seconds before running the SPFL algorithm when notified of a network going down
or a new network that's been added to the topology.
The idea of this is to allow the network to stabilize before running the OSPF algorithm.
Notice the minimum hold time between two consecutive SPF algorithm calculations is 10 seconds.
So in other words, we will not run the SPF algorithm continuously.
There is a gap of 10 seconds between calculations.
We can see that the backbone Area Zero has been enabled in Misrata and three interfaces have been put
into this area.
No authentication has been enabled on this area and we lost executed the algorithm about 5 minutes ago
and it executed three times.
So let's enable OSPF on router two and see how the output changes.
So in rather to show IP interface brief will allow me to see the interfaces configured on this router.