What is Ethernet?

Have you heard of IEEE 802.3? It has a long history and has to
do with our topic today, Ethernet. before we get started on today’s video if you love our videos, be sure to click the
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miss another one! Ethernet is a
communication standard that was developed in the early ’80s
to network computers and other devices in a local environment such
as a home or a building. This local environment is defined
as a LAN (Local Area Network) and it connects multiple devices
so that they can create, store and share information
with others in the location. Ethernet is a wired system that started with
using coaxial cable and has successfully progressed to
now using twisted pair copper wiring and fiber optic wiring. Let’s break for a trivia question. Who invented twisted
pair wiring? Alexander Graham Bell invented
twisted pair wiring in 1881. In 1983, Ethernet
was standardized into the standard IEEE 802.3 by the Institute of Electrical
and Electronic Engineers (IEEE). This standard defined the physical layer and the MAC (media access control) portion
of the data link layer of wired Ethernet. These two layers are defined
as the first two layers in the OSI (Open Systems
Interconnection) model The “physical” layer consists
of the following components: Cabling and Devices. First, let’s take a look
at Ethernet Cabling; As stated previously, Ethernet
cables come as coaxial cable, which is not very common
except in older installations, twisted pair, and fiber optic. The most common cable
is twisted pair cables, with the latest being Category
6 with speeds up to 1 Gbps and Cat6a and Cat 7 with
speeds up to 10 Gbps. Category 5 and 5e cables are both still
used in many existing applications but handle the lower
speeds between 10 Mbps to 100 Mbps but are more
susceptible to noise. The Ethernet twisted pair utilizes
RJ-45 eight-pin connectors at either end of the cable that
is pinned for transmitting and receiving data in either
half or full-duplex mode. Half-duplex transmits data
in one direction at a time while “full-duplex” allows
data to be transmitted in both directions
at the same time. Full-duplex in Ethernet can be
achieved by using two pairs of wires to allow data to travel both
directions simultaneously. Fiber optic cable uses glass
or plastic optical fiber as a conduit for light
pulses to transmit data. It has allowed Ethernet to travel
farther distances at higher speeds. Fiber optic cables use several
different types of connectors that vary depending on
your application needs. Some of the different types are SFP (Small Form Pluggable or
Small Factor Pluggable) and SC (Subscriber Connector, also known as
Square Connector or Standard Connector). In order to use fiber optic
in an Ethernet network that utilizes twisted
pair Ethernet cabling, you need to use an Ethernet
to fiber converter that will allow your network to take advantage
of the higher speeds of fiber optic and lengthen the distance that
the Ethernet network can reach. How about the Ethernet devices? Ethernet devices are
consist of computers, printers or any device which
either have an internal NIC (Network Interface Card) or an external one that
is USB or PCI based. “Switches” and “Routers” that act
as the director of the network and connect multiple computers or even networks together
to enable communication between all the different devices. “Gateways” or “Bridges” are used to connect
multiple Ethernet networks together and allow communication
across them. Gateways connect two
dissimilar networks together while a bridge connects two
similar networks together so that you only see one network. Now that we have discussed the basic
physical components of Ethernet, let’s move into the second layer of
the OSI model, the “data link” layer. The data link layer can be
split into two sections; the Logical Link Control (LLC) and the Media Access Control (MAC). The Logical Link Control
establishes paths for data on the Ethernet to
transmit between devices. The Media Access Control
uses hardware addresses that are assigned to Network
Interface Cards (NIC) to identify a specific
computer or device to show the source and destination
of data transmissions. Ethernet transmits data packets
in this data link layer by using an algorithm called CSMA/CD (Carrier Sense Multiple Access
with Collision Detection). CSMA/CD is used as a
standard for Ethernet to reduce data collisions and increase
successful data transmission. The algorithm first checks to see
if there is traffic on the network. If it does not find any, it will send out the first bit of information
to see if a collision will occur. If this first bit is successful, then it will send out the other bits
while still testing for collisions. If a collision occurs, the algorithm
calculates a waiting time and then starts the
process all over again until the full
transmission is complete. When you use the faster
Ethernets in full-duplex modes and incorporate switches, then you are utilizing
a star topology between the switch
ports and the devices. This allows for more direct
transmission paths and fewer collisions as compared to a bus topology where
all devices share the same paths. Ethernet capabilities are quickly changing
with new technologies emerging every day. And while we are currently on the brink
of successfully moving into speeds higher than the current 1 Gbps with 10 Gbps
emerging over the last few years, these new Ethernet
technologies will be costly. Also, your possibilities
for the information world can seem endless when you connect
this Ethernet local area network to the internet to create a very
large WAN (Wide Area Network). But that is a story for another day. All in all, Ethernet is popular because it strikes a good
balance between speed, cost, and ease of installation. These benefits, combined with wide
acceptance in the computer marketplace and the ability to support virtually
all popular network protocols. Want to learn PLC programming
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