In this video,
we're going to discuss the various ethernet issues
that you may experience,
such as duplexing issues
and how you can troubleshoot different issues
using LED status indicators.
So let's talk first about those LED status indicators.
These tend to be used to diagnose an issue
in both fiber optic and copper connections.
Most of your network interface cards
are going to have two lights on the back of that card,
one for an activity light
and one for a link speed light.
Now, the activity light is going to be used
to show the status of the link when it's in use.
If the activity light is off,
that means there's no link or connection being established.
If the activity light is solid orange,
this indicates there's a link or a connection established
with this network interface card
and the upstream device that it's connected to,
such as your switch.
But when you start to see that light blinking orange,
this indicates there's data activity occurring
over that link or connection.
So if you're trying to determine
if the issue exists with the network interface card
or the network itself,
a quick look at that activity light
can be a good hint during your network troubleshooting.
Because if you see an orange light,
either solid or blinking,
this means there's a valid connection
or link between your NIC and the switch.
The second light you're going to find on a NIC
is the link speed light.
Now the speed LED will either be off, orange
or green, depending on the speed
of the network interface cards connection.
If your connection is operating at one gigabit per second,
you're going to see a green light.
If you have a hundred megabit per second connection,
you're going to see an orange light.
If it's off, that's going to indicate you're operating
at the slow speed of 10 megabits per second.
These settings may change
depending on your network interface card, but for most NICs,
this is a pretty accurate description.
Now, these lights aren't just used with the NICs though,
in a workstation or server.
You also are going to have your network switches having similar
LEDs for each ethernet port that they have.
So you can determine very quickly by looking at it,
the status and activity level for each port on that switch.
Next, we have duplexing issues.
Now, the most common duplexing issue is a duplex mismatch.
A duplex mismatch can occur with two ends
of an ethernet connection attempt
to negotiate a full duplex connection.
But one of those devices thinks the connection
is full duplex and the other one thinks it's half duplex.
Now, you can identify this type of condition
by observing a high rate
of packet loss without the high rate of jitter
that would normally be typical of congestion.
Also, you're going to see a high receive error rate
and rug packets showing up
when you're using a duplex mismatch.
Now to prevent a duplex mismatch,
you should ensure both devices are configured
to use auto negotiate when they're
establishing their connections.
If they fail to auto negotiate the connection themselves,
you can manually configure them as full duplex
or half duplex, depending on your network conditions.
Remember, your conditions should be set
to full duplex if you're using switches on your network
because each switch port
is considered its own collision domain.