1
00:00:00,360 --> 00:00:08,820
Now, this may be a packaged tracer issue, but let's confirm that show ip protocols.

2
00:00:08,820 --> 00:00:12,720
We are running OSPF on this router.

3
00:00:13,590 --> 00:00:15,990
It's enabled on all interfaces.

4
00:00:16,910 --> 00:00:19,610
Can we ping rather three?

5
00:00:19,640 --> 00:00:22,700
Yes, we can show ip ospf neighbor.

6
00:00:23,240 --> 00:00:25,160
The neighbor relationship is full.

7
00:00:27,350 --> 00:00:29,270
The loopback address is configured.

8
00:00:30,140 --> 00:00:36,320
OSPF is running on all interfaces in area to show IP OSPF database.

9
00:00:36,770 --> 00:00:46,070
We have two routers configured in area two, but notice it's still got the wrong router ID in the database.

10
00:00:46,700 --> 00:00:48,980
So let's do a clear IP.

11
00:00:50,380 --> 00:00:55,480
OSPF process to re-establish the neighbor relationships.

12
00:00:57,100 --> 00:01:01,750
Relationship has now come up show IP OSPF database.

13
00:01:03,420 --> 00:01:04,200
That looks better.

14
00:01:04,200 --> 00:01:11,810
We've got rather three as a rudder in area two it still showing rather two.

15
00:01:11,820 --> 00:01:19,560
But notice that age is very high and is incrementing so that will eventually time out.

16
00:01:20,340 --> 00:01:29,220
Rather two is not configured in area to show IP protocols.

17
00:01:29,460 --> 00:01:34,980
Router two is configured in area zero and area one.

18
00:01:34,980 --> 00:01:42,870
So this is because of the incorrect router ID previously that will eventually time out.

19
00:01:43,290 --> 00:01:45,600
But let's check if out of three.

20
00:01:46,900 --> 00:01:50,380
He's learning about the loopback of router four.

21
00:01:50,680 --> 00:01:51,880
Yes, it is.

22
00:01:52,000 --> 00:01:55,540
So we got some sudden updates there to the database.

23
00:01:56,380 --> 00:02:00,510
But router three can now ping router four.

24
00:02:00,670 --> 00:02:02,230
That looks good.

25
00:02:02,890 --> 00:02:08,560
Notice on router two we see that a OSPF neighbor went down and then it came up again.

26
00:02:09,190 --> 00:02:14,500
But now that the network has settled down, we can ping router four.

27
00:02:14,830 --> 00:02:22,090
We have the loopback of router four in the routing table show ip ospf database.

28
00:02:23,020 --> 00:02:26,080
Shows us that we have rather one and rather two.

29
00:02:26,830 --> 00:02:35,440
In area one there is one designated router in Area one and we've learnt about routes from other areas

30
00:02:35,830 --> 00:02:42,310
such as the loopback of router four and we can ping the loopback of router four.

31
00:02:43,120 --> 00:02:50,560
So to confirm that things are working, we can ping the loopback of router one, router two, router

32
00:02:50,560 --> 00:02:54,070
three and router four.

33
00:02:55,380 --> 00:03:05,310
And on right before we can ping the loopback of writer one, router two and router three, we've successfully

34
00:03:05,580 --> 00:03:10,920
corrected the errors in this network and it's all working now.

35
00:03:10,950 --> 00:03:19,020
We fixed the router ID on router three and we reset the OSPF process on router four to force things

36
00:03:19,020 --> 00:03:20,070
to happen quicker.

37
00:03:20,610 --> 00:03:22,650
Show IP OSPF database.

38
00:03:23,410 --> 00:03:30,500
But it still has rather four in the OSPF database, but that's going to time out.

39
00:03:30,680 --> 00:03:38,420
Notice how large the AG is compared to other routers in the OSPF database.

40
00:03:39,020 --> 00:03:40,580
I hope you found that useful.

41
00:03:40,610 --> 00:03:46,970
Make sure that you understand and can troubleshoot OSPF for the CCNA exam.