In the previous video, we already add 1 new router to the topology, so now we have 3 router here. 2
Next in this video, we are going to configure ospf so all pc will able to communicate each others. 3
Because for now pc 1 and pc 2 should not able to communicate with pc 3. Let’s test it. 4
Pc 2 to pc 3, failed, test again, still failed, pc 1 to pc 3, failed, test again, still failed. 5
Okay so now pc 1 and pc 2 can not communicate with pc 3. 6
This is why we need to configure an ospf. 7
The question is, where we need to add ospf configuration? 8
Here in router 1, we don’t add any ip address, so there is no new connected network, 9
this is means we don’t need to add any configuration on router 1. 10
In the router 2, we add new ip address, which is fa1/0, the ip address is 10.20.20.1/30, 11
so we have new connected network here, which is 10.20.20.0/30 connected to fa1/0. 12
Because router 2 have new connected network, so we will need to add new configuration here. 13
And last router 3, we don’t configure ospf yet, so absolutely we will need 14
to add ospf configuration here. Let’s write the connected network of router 3. 15
Router3 should have 2 connected network, 16
10.20.20.0/30 connected to fa0/0, and 192.168.3.0/24 connected to fa0/1. 17
Okay now let’s configure ospf. Let’s start with router 2. Remember that here 18
we use ospf process id 2, if you forgot the ospf process id, you can check it first, do show run, 19
here we can see that we use process id 2. 20
So here router ospf 2, next let’s advertise the new network, 21
network 10.20.20.0 and then the wildcard bits. Here we use prefix /30, 22
and the subnetmask for prefix /30 is 255.255.255.252, 23
let’s calculate the wildcard bits, 255.255.255.255 minus by subnetmask . 24
255 minus by 252 is 3, 255 minus by 255 0, 255 minus by 255 0 and 255 minus by 255 is also 0. 25
So for prefix /30, the wildcard bits is 0.0.0.3. Let’s back to the configuration. 26
Here let’s put the wildcard bits, 0.0.0.3. and then area 0. 27
Okay now we have done for router 2, next let’s configure router 3. 28
Router ospf and then the process id, you are free to use anything, but in this case, 29
let’s say we will use 3. And then next, let’s advertise the connected network. 30
Network 10.20.20.0 and the wildcard bits for prefix /30 is 0.0.0.3 and then area 0. 31
Next let’s advertise the network that connected to pc 3, 32
so network 192.168.3.0 wildcard bits for prefix /24 is 0.0.0.255 and then area 0. 33
Okay now we have done configuring ospf on router 2 and router 3. Let’s check it, 34
First, let’s see the routing table on router 1, 35
enable, show ip route. Here we can see that router 1 have route to the pc 3, 36
and this route is added automatically by ospf. Let’s also check on router2, 37
here we can see that router 2 also have route to pc 3 automatically. Here the label is O, 38
this is means ospf. 39
Let’s also check on router 3, do show ip route, 40
here we can see that on router 3 also have route to pc 1 and pc 2 automatically. 41
So for now pc 1, pc 2, and pc 3 should be able to communicate each others. Let’s try. 42
Pc 1 to pc 2, success, pc 2 to pc 3, failed, test again, okay here success. 43
Okay so now we have done configuring ospf on 3 router. 44
I think enough for this video 45
Thank you for watching and see you on the next video.