1
00:00:01,040 --> 00:00:09,050
It's brought a one which is the device and all paying Rodda to from rodded one to see if Ping's succeed

2
00:00:10,400 --> 00:00:14,480
so paying ten more than two Ping's succeed.

3
00:00:15,750 --> 00:00:21,410
But notice we are getting a message that there is a duplex mismatch between the Rodda and to the 20

4
00:00:21,410 --> 00:00:23,810
951 switch.

5
00:00:23,970 --> 00:00:27,060
So we're being told that there's a duplex problem here.

6
00:00:29,520 --> 00:00:33,230
And on the switch we are seeing that there's a duplex mismatch on Foster.

7
00:00:33,230 --> 00:00:36,140
Ethan it deserves three to the Rodda.

8
00:00:36,510 --> 00:00:44,010
So we've been told that there's a duplex problem here but we also told that there's a duplex issue on

9
00:00:44,010 --> 00:00:44,340
Fosset.

10
00:00:44,340 --> 00:00:49,560
Ethan it is 0 4 to the 20 9:52 switch on Fosset.

11
00:00:49,570 --> 00:00:50,930
Ethan It's 0 4.

12
00:00:51,190 --> 00:00:53,030
So there's a problem here as well.

13
00:00:55,350 --> 00:01:01,780
Now you may not be physically connected to the console and hence you may not see these issues.

14
00:01:01,800 --> 00:01:09,370
That's a good reason to use Aslaug server or a management application from a company such a solar winds.

15
00:01:09,390 --> 00:01:18,680
So let's ping rodder to again ping succeeds so pings aren't necessarily a good way to test for Duplaix

16
00:01:18,680 --> 00:01:20,220
mismatches.

17
00:01:20,270 --> 00:01:28,390
However I'll do an extended ping to that routers.

18
00:01:28,440 --> 00:01:30,670
Let's try that again.

19
00:01:30,840 --> 00:01:42,760
10:01 going to I'll send a thousand pings and I'm going to make the datagram size a large size.

20
00:01:42,880 --> 00:01:49,180
So we want to send a lot of traffic on to the network and hopefully we'll encounter a problem.

21
00:01:49,270 --> 00:01:50,350
And there you go.

22
00:01:50,350 --> 00:01:54,620
We've got a message saying a late collision has occurred.

23
00:01:55,240 --> 00:02:04,140
So this is a problem you may encounter one side may tell you that there are late collisions as you can

24
00:02:04,140 --> 00:02:05,100
see over there.

25
00:02:05,370 --> 00:02:08,920
We're getting a number of late collisions on the other side.

26
00:02:08,910 --> 00:02:10,050
We're not seeing that

27
00:02:13,880 --> 00:02:14,630
on the switch.

28
00:02:14,630 --> 00:02:16,850
Show interface if there's zero slushed three

29
00:02:20,310 --> 00:02:24,450
we're not seeing a lot of late collisions.

30
00:02:24,450 --> 00:02:31,790
The configuration of that interface is set to a speed of 10 meg and Duplaix a fool.

31
00:02:32,190 --> 00:02:43,200
But notice on the side show run interface if it's zero the side has its speed set to 100.

32
00:02:43,530 --> 00:02:46,950
Let's confirm that show interface zero.

33
00:02:46,980 --> 00:02:54,120
Notice the Duplaix is half speed is set in this example to 10 megabits per second.

34
00:02:54,210 --> 00:03:01,560
So the router because it can't negotiate properly with the other device in this case the 28 on 50 switch

35
00:03:02,610 --> 00:03:10,670
has set its speed to a valley of 10 make half duplex.

36
00:03:10,880 --> 00:03:19,920
So the point to remember is when there is a mismatch the site that is set for half duplex will see a

37
00:03:19,920 --> 00:03:22,620
late collisions on the connection.

38
00:03:22,620 --> 00:03:31,400
But this only occurs when you sending enough traffic so he stented ping doesn't show that problem but

39
00:03:31,400 --> 00:03:37,760
when a large amount of traffic is sent on this half duplex connection we are getting a late collusions

40
00:03:42,380 --> 00:03:50,490
on the switch side striving to face if zero slash 3.

41
00:03:50,740 --> 00:03:53,910
Notice the speed is full duplex 10 megabits per second.

42
00:03:54,310 --> 00:03:57,320
Whereas on the router it's half duplex 10 megabits per second.

43
00:03:59,810 --> 00:04:06,380
Even though I configured it to use 100 megabits per second it's using a failed back position of the

44
00:04:06,380 --> 00:04:10,490
worst case scenario which is 10 make half duplex.

45
00:04:10,700 --> 00:04:13,430
And in this case we're having that problem.

46
00:04:13,430 --> 00:04:16,780
Notice this is 100 base TXI effects.

47
00:04:16,860 --> 00:04:19,400
The side is 100 based x.

48
00:04:19,700 --> 00:04:26,510
So in this example the router has gone for half duplex 10 megabits per second whereas the switch is

49
00:04:26,510 --> 00:04:32,490
using 10 meg full duplex and hence we've got a duplex mismatch.

50
00:04:32,490 --> 00:04:39,870
So in summary we get told by CGP that there is a duplex mismatch the local interface is not to using

51
00:04:39,870 --> 00:04:47,130
full duplex whereas the other side is using full duplex pinging a device doesn't tell us that there's

52
00:04:47,130 --> 00:04:48,290
a problem.

53
00:04:48,570 --> 00:04:50,550
But when large packets are sent

54
00:04:53,880 --> 00:04:56,700
uses main count the drops

55
00:04:59,770 --> 00:05:04,240
put throughput and you may see late collisions.

56
00:05:04,240 --> 00:05:06,470
So let me saturate that link again.

57
00:05:09,250 --> 00:05:13,580
Send a thousand pings large datagram size

58
00:05:17,720 --> 00:05:20,010
show interface zero slash three

59
00:05:23,830 --> 00:05:29,970
notice we are now seeing the late collisions taking place on the interface.

60
00:05:30,030 --> 00:05:38,490
So on the half duplex side we see this output of late collisions on the interface show interface is

61
00:05:38,640 --> 00:05:39,230
zero.

62
00:05:39,250 --> 00:05:44,290
Notice the number of late collisions has increased on the full duplex side.

63
00:05:44,290 --> 00:05:50,310
We may get input errors such as CRC errors or out frames.

64
00:05:50,380 --> 00:05:54,440
So in this example weve got 28 input errors 15 CCS.

65
00:05:54,670 --> 00:05:59,800
We aren't seeing any runs but we are receiving duplex mismatch messages.