1 00:00:00,500 --> 00:00:09,000 In the previous video, we already add 1 new router to the topology, so now we have 3 router here. 2 00:00:09,756 --> 00:00:18,581 Next in this video, we are going to configure ospf so all pc will able to communicate each others. 3 00:00:19,181 --> 00:00:27,820 Because for now pc 1 and pc 2 should not able to communicate with pc 3. Let’s test it. 4 00:00:28,539 --> 00:00:42,873 Pc 2 to pc 3, failed, test again, still failed, pc 1 to pc 3, failed, test again, still failed. 5 00:00:43,499 --> 00:00:48,938 Okay so now pc 1 and pc 2 can not communicate with pc 3. 6 00:00:49,566 --> 00:00:53,271 This is why we need to configure an ospf. 7 00:00:53,937 --> 00:00:58,294 The question is, where we need to add ospf configuration? 8 00:00:59,434 --> 00:01:07,353 Here in router 1, we don’t add any ip address, so there is no new connected network, 9 00:01:07,816 --> 00:01:12,953 this is means we don’t need to add any configuration on router 1. 10 00:01:14,686 --> 00:01:25,761 In the router 2, we add new ip address, which is fa1/0, the ip address is 10.20.20.1/30, 11 00:01:26,500 --> 00:01:37,480 so we have new connected network here, which is 10.20.20.0/30 connected to fa1/0. 12 00:01:38,286 --> 00:01:44,564 Because router 2 have new connected network, so we will need to add new configuration here. 13 00:01:45,271 --> 00:01:52,030 And last router 3, we don’t configure ospf yet, so absolutely we will need 14 00:01:52,030 --> 00:01:58,551 to add ospf configuration here. Let’s write the connected network of router 3. 15 00:01:59,122 --> 00:02:02,019 Router3 should have 2 connected network, 16 00:02:03,220 --> 00:02:16,536 10.20.20.0/30 connected to fa0/0, and 192.168.3.0/24 connected to fa0/1. 17 00:02:17,674 --> 00:02:24,949 Okay now let’s configure ospf. Let’s start with router 2. Remember that here 18 00:02:24,949 --> 00:02:35,218 we use ospf process id 2, if you forgot the ospf process id, you can check it first, do show run, 19 00:02:38,407 --> 00:02:42,000 here we can see that we use process id 2. 20 00:02:43,168 --> 00:02:50,384 So here router ospf 2, next let’s advertise the new network, 21 00:02:52,515 --> 00:03:02,776 network 10.20.20.0 and then the wildcard bits. Here we use prefix /30, 22 00:03:03,424 --> 00:03:10,653 and the subnetmask for prefix /30 is 255.255.255.252, 23 00:03:13,300 --> 00:03:24,999 let’s calculate the wildcard bits, 255.255.255.255 minus by subnetmask . 24 00:03:25,608 --> 00:03:39,946 255 minus by 252 is 3, 255 minus by 255 0, 255 minus by 255 0 and 255 minus by 255 is also 0. 25 00:03:40,686 --> 00:03:50,882 So for prefix /30, the wildcard bits is 0.0.0.3. Let’s back to the configuration. 26 00:03:54,513 --> 00:04:03,682 Here let’s put the wildcard bits, 0.0.0.3. and then area 0. 27 00:04:06,381 --> 00:04:12,590 Okay now we have done for router 2, next let’s configure router 3. 28 00:04:13,553 --> 00:04:21,617 Router ospf and then the process id, you are free to use anything, but in this case, 29 00:04:21,617 --> 00:04:28,845 let’s say we will use 3. And then next, let’s advertise the connected network. 30 00:04:29,382 --> 00:04:41,684 Network 10.20.20.0 and the wildcard bits for prefix /30 is 0.0.0.3 and then area 0. 31 00:04:42,554 --> 00:04:47,176 Next let’s advertise the network that connected to pc 3, 32 00:04:47,844 --> 00:05:00,776 so network 192.168.3.0 wildcard bits for prefix /24 is 0.0.0.255 and then area 0. 33 00:05:02,102 --> 00:05:09,000 Okay now we have done configuring ospf on router 2 and router 3. Let’s check it, 34 00:05:09,341 --> 00:05:13,068 First, let’s see the routing table on router 1, 35 00:05:13,527 --> 00:05:21,883 enable, show ip route. Here we can see that router 1 have route to the pc 3, 36 00:05:22,363 --> 00:05:29,792 and this route is added automatically by ospf. Let’s also check on router2, 37 00:05:33,760 --> 00:05:41,693 here we can see that router 2 also have route to pc 3 automatically. Here the label is O, 38 00:05:41,816 --> 00:05:44,004 this is means ospf. 39 00:05:44,915 --> 00:05:49,113 Let’s also check on router 3, do show ip route, 40 00:05:50,100 --> 00:05:57,146 here we can see that on router 3 also have route to pc 1 and pc 2 automatically. 41 00:05:57,767 --> 00:06:06,229 So for now pc 1, pc 2, and pc 3 should be able to communicate each others. Let’s try. 42 00:06:06,813 --> 00:06:17,446 Pc 1 to pc 2, success, pc 2 to pc 3, failed, test again, okay here success. 43 00:06:18,340 --> 00:06:23,217 Okay so now we have done configuring ospf on 3 router. 44 00:06:23,713 --> 00:06:26,048 I think enough for this video 45 00:06:26,165 --> 00:06:29,598 Thank you for watching and see you on the next video.