Ethernet clearly the most popular access protocol, but

Ethernet is a network protocol that controls how
data is transmitted over a LAN system. It was commercially introduced in 1980 and first
standardised in 1983 as IEEE 802.3, and has since been refined to support higher bit rates and longer link distances. A Local Area Network
(LAN) is a communication network that interconnects a variety of data
communication devices within a small geographical area like a room, an office, a building or a campus. LAN
are also capable of transmitting data at “high data transfer rates” where the
newest LAN can transmit data at 10 billion bits per second and higher.The
wired version of Ethernet is based primarily on the star-wired bus topology and
uses the Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
medium access protocol. To be a little more precise, the network logically acts
as a bus, but looks like a star. While, the CSMA/CD works on a first-come,
first-served basis, supports half-duplex and full-duplex connections, and is
clearly the most popular access protocol, but it suffers from collisions of
data frames during high-usage periods when hubs are employed. Over time,
Ethernet has largely replaced competing wired LAN technologies such as Token Ring, Fiber Distributed Data Interface (FDDI) and Attached Resource
Computer NETwork (ARCNET).
The
benefits of wired Ethernet are power over Ethernet (IEEE standard 802.3af).
Suppose you want to place a Network Interface Card (NIC) in a device, but do
not want to or cannot connect the device to an electric source. For example,
you want to install a surveillance camera that transfers its signal first over
Ethernet and then over the Internet. Normally, you would install the camera,
then install both an Ethernet connection and an electric connection. But with
power over Ethernet (PoE), you can send electrical power over the Ethernet
connection, which can be used to power the camera.

However,
one of the drawbacks is the capability to provide the Ethernet hub or switch
with enough power such that the power can then be distributed over Ethernet
lines to the various devices.A
local area network (LAN) that is not based primarily on physical wiring but
uses wireless transmissions between workstations is a wireless LAN, or wireless
Ethernet. By attaching a transmitter/receiver to a special network interface
card on a workstation or laptop, and similar hardware on a device called an
access point, it is possible to transmit data between a workstation and network
at speeds into the millions of bits per second.

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The
advantages of wireless Ethernet are the workstation can be located anywhere
within the acceptable transmission range. This acceptable range varies with the
wireless technology used but typically falls between a few feet and several
hundred feet. Clearly, one of the strongest advantages of a wireless LAN is the
reduction in wiring. No cabling is necessary for the user device to communicate
with the network. This makes a wireless LAN a perfect solution for many
different applications.

On
the other hand, the security of wireless Ethernet is poor as anyone within
range can use it unless kept secured with a security password or key. Besides,
a wireless LAN signal may be interfered when it is affected by walls,
electronic equipment, distance from router or number of computers connected.Token
Ring LAN technology was developed by IBM in the middle 1980s as a fast and
reliable alternative to Ethernet. Token Ring technology uses a different concept,
known as token passing, for allowing network adapters to transmit data on the
media.The Token Ring LAN uses the
star-wired ring topology for the hardware and a round-robin protocol for the
software. Token Ring operates in Ring Topology, in a logical ring, where the central device which is used to connect
the network devices (Servers, Workstations, Printers, Scanners etc.) hosts an
internal ring, where access to the network media for a network device is given
only by the possession of a token that is passed from device to device on the
ring. The star-wired ring is capable of supporting only one channel of
information which only flows in one direction around the ring, moving from
workstations to workstations. It uses a token passing protocol, so that the
machine can only use the network when it has control of the token.The
central device which is used to connect the network devices is called as a
Multistation Access Unit (MAU). MAU accepts data from a workstation and
transmits this data to the next workstation in the ring.   Token
Ring is more sophisticated than Ethernet., and it includes a number of built-in diagnosis and
correction mechanisms that can help troubleshoot network problems. Token Ring
networks does not produce the collisions that can take place in the Ethernet network. This is because only one machine can use the
network at any given time. The main difference of Ethernet and Token Ring is that, Ethernet uses Star Topology and Token ring uses logical Ring Topology.The
principal benefits of Token Ring are there will be no collisions occurs. This
is because there is only one token in the entire network, so only one
workstation may transmit at a time. When a workstation has completed its
transmission, it passes the token on to the downstream neighbouring
workstation. Only the workstation holding the token can transmit, so there is
no need for any workstations to listen for a collision. However,
when it is under lightly loaded condition, there is some efficiency with Token
Ring because a workstation must wait for the token to come around before
transmitting. A major disadvantage of the token ring access protocol is the
complexity of the software needed to maintain the token. This software had to
address important question such as “What happens if the token ring disappears?”
“If the token ring disappears, who generates a new token?” “Is it possible for
two stations to generate a token, thus resulting in two tokens on the ring?” Token
Ring LAN have almost always lagged behind CSMA/CD networks with regard to
transmission speed. When CSMA/CD first became popular, the typical transmission
speed was 10 Mbps. Token ring when it first appeared, had a transmission speed
of only 4 Mbps.