-: Ethernet issues. 2 2
In this video we're going to discuss 3 3
the various Ethernet issues that you may experience 4 4
such as duplexing issues, 5 5
and how you can troubleshoot different issues 6 6
using LED status indicators. 7 7
So let's talk first about those LED status indicators. 8 8
These tend to be used to diagnose an issue 9 9
in both fiber optic and copper connections. 10 10
Most of your network interface cards 11 11
are going to have two lights on the back of that card. 12 12
One for an activity light and one for a link speed light. 13 13
Now the activity light is going to be used to show 14 14
the status of the link when it's in used. 15 15
If the activity light is off 16 16
that means there's no link, 17 17
or connection being established. 18 18
If the activity light is solid orange 19 19
this indicates there's a link or a connection established 20 20
with this network interface card, 21 21
and the upstream device that it's connected to 22 22
such as your switch. 23 23
But when you start to see that light blinking orange, 24 24
this indicates there's data activity 25 25
occurring over that link or connection. 26 26
So if you're trying to determine if the issue exists 27 27
with the network interface card, or the network itself, 28 28
a quick look at that activity light can be a good hint 29 29
during your network troubleshooting. 30 30
Because if you see an orange light, 31 31
either solid or blinking, 32 32
this means there's a valid connection or link 33 33
between your NIC and the switch. 34 34
The second light you're going to find on a NIC 35 35
is the link speed light. 36 36
Now the speed LED will either be off, orange, or green, 37 37
depending on the speed 38 38
of the network interface cards connection. 39 39
If your connection is operating at one gigabit per second 40 40
you're going to see a green light. 41 41
If you have 100 megabit per second connection 42 42
you're going to see an orange light, 43 43
if it's off that's going to indicate you're operating 44 44
at a slow speed of 10 megabits per second. 45 45
These settings may change depending 46 46
on your network interface card, 47 47
but for most NICs this is a pretty accurate description. 48 48
Now, these lights aren't just used with the NICs though 49 49
in a workstation or server, 50 50
you also are going to have your network switches 51 51
having similar LEDs for each Ethernet port that they have 52 52
so you can determine very quickly by looking at it 53 53
the status and activity level for each port on that switch. 54 54
Next, we have duplexing issues. 55 55
Now the most common duplexing issue is a duplex mismatch. 56 56
A duplex mismatch can occur 57 57
when two ends of an Ethernet connection 58 58
attempt to negotiate a full duplex connection, 59 59
but one of those devices 60 60
thinks the connection is full duplex, 61 61
and the other one thinks it's half duplex. 62 62
Now, you can identify this type of condition 63 63
by observing a high rate of packet loss 64 64
without the high rate of jitter 65 65
that would normally be typical of congestion. 66 66
Also, you're going to see a high received error rate, 67 67
and runt packets showing up 68 68
when you're using a duplex mismatch. 69 69
Now to prevent a duplex mismatch, 70 70
you should ensure both devices are configured 71 71
to use auto negotiate 72 72
when they're establishing their connections. 73 73
If they fail to auto negotiate the connection themselves, 74 74
you can manually configure them as full duplex, 75 75
or half duplex depending on your network conditions. 76 76
Remember, your conditions should be set to full duplex 77 77
if you're using switches on your network, 78 78
because each switch port is considered 79 79
its own collision domain.