NAME: R.KEERTHI SREE
DEPARTMENT: BACHELOR OF COMPUTER APPLICATIONS
COLLEGE: MARUDHAR KESARI JAIN COLLEGE FOR WOMEN,VANIYAMBADI.
Computer Network
ABSTRACT:
A computer network is a set of computers connected together for
the purpose of sharing resources. The most common resource shared today is connection
to the Internet. Other shared resources can include a printer or a file server. A computer network is a digital
telecommunications network which allows nodes to share resources. In computer
networks, network computing devices exchange data with each other using a data.
The connection nodes are established using either a wired media or wireless
media.
WIRED COMMUNICATION:
·
A
wired network is a common type of wired configuration.most wired networks use
Ethernet cables to transfer data between
connected PCs.
·
In
a small wired network,a single router may be used to connect all the computers.
·
A large
networks often involve multiple routers or switches that connect to each other.
·
Examples for wired network are telephone network, cable television
,internet access,fiber optic communication, twisted pair, coaxial cable,
optical fiber.
WIRELESS COMMUNICATION:
·
Wireless
networking is a method by which homes, telecommunication network and business
installations avoid the costly process of introducing cables into a building or
as a connection between various equipment locations.
·
Examples
for wireless network are cellphone networks, Wireless Local Area Network(WLAN),wireless sensor networks, satellite
communication networks and terrestrial microwave networks.
TOPOLOGIES OF COMPUTER NETWORK:
·
Computer networks
can be broken down historically into topologies, which is a technique of connecting computers.
·
The most common
topology today is a collapsed ring.
This is due to the success of a network protocol called the Ethernet.
·
This protocol, or
network language, supports the Internet, Local Area Networks, and Wide Area
Networks.
·
The different types
of topologies are as follows:
Ø Star topology
Ø Bus Topology
Ø Ring Topology
STAR TOPOLOGY:
·
A star
topology is a design of a network where a central node extends a
cable to each computer on the network.
·
On a star network, computers are connected
independently to the center of the network.
·
If a cable is broken, the other computers can
operate without problems. A star topology requires a lot of cabling.
·
A star topology is a topology for a Local Area
Network(LAN) .
BUS TOPOLOGY:
·
A bus
topology is another type of design where a single cable connects
all computers and the information intended for the last node on the network
must run through each connected computer.
·
If a cable is broken, all computers connected
down the line cannot reach the network. The benefit of a bus topology is a
minimal use of cabling.
RING TOPOLOGY:
·
In the ring topology,the computers are
connected via a single cable, but the end nodes also are connected to each
other.
·
In this design, the signal circulates through
the network until it finds the intended recipient.
·
If a network node is not configured properly,
or it is down temporarily for another reason, the signal will make a number of
attempts to find its destination.
INVENTIONS
OF COMPUTER NETWORKS:
|
ü
In the late
1950s, early networks of computers included the military radar system Semi-Automatic
Ground Environment(SAGE)
ü
In 1959, Anatolii
Ivanovich Kitov proposed to the Central Committee
of the Communist Party of the Soviet Union a detailed
plan for the re-organisation of
the control of the Soviet armed forces and of the Soviet economy on the basis
of a network of
computing centres.
ü
In 1960, the
commercial airline reservation system semi-automatic
business research environment (SABRE) went
online with
two connected mainframes.
ü
In 1962, J.C.R.
Licklider developed a working group he
called the "Intergalactic Computer Network", a precursor to the
ARPANET, at Advanced Research projects Agency(ARPA).
ü
In 1964,
researchers at Dartmouth College developed the Dartmouth Time Sharing
System for distributed users of large
computer systems. The same year, at Massachusetts
Institute of Technology , a research group
supported by General Electric
and Bell Labs used
a computer to route and manage telephone connections.
ü
Throughout the
1960s, Leonard Kleinrock, Paul
Baran, and Donald Davies independently developed network systems that
used packets to transfer
information between computers over a network.
ü
In 1965, Thomas
Marill and Lawrence G. Roberts created
the first wide area network(WAN).
This was an immediate precursor
to the ARPANET,
of which Roberts became program manager.
ü
Also in
1965, Western Electric introduced
the first widely used telephone switch
that implemented true computer control.
ü
In 1969, the University
of California at Los Angeles, the Stanford
Research Institute, the University of
California at
Santa
Barbara,and the University of Utahbecame connected as the beginning of the ARPANET network using 50 kbit/s circuits.
ü
In 1972,
commercial services using X.25were
deployed, and later used as an underlying infrastructure for expanding
TCP/IP networks.
ü
In 1973, Robert
Metcalfe wrote a formal memo at Xerox
PARC describing Ethernet, a networking system that was based on the
Aloha
network, developed in the 1960s by Norman
Abramson and colleagues at the University
of Hawaii.
ü
In July
1976, Robert Metcalfe and David
Boggs published their paper "Ethernet:
Distributed Packet Switching for Local
Computer Networks and collaborated
on several patents received in 1977 and 1978. In 1979, Robert Metcalfe
pursued making
Ethernet an open standard.
ü
In 1976, John
Murphy of datapoint corporation created ARCNET, a token-passing network first used to share storage devices.
ü In 1995, the transmission speed capacity for Ethernet increased from
10 Mbit/s to 100 Mbit/s. By 1998, Ethernet supported
transmission speeds of a Gigabit.
Subsequently, higher speeds of up to 100 Gbit/s were added (as of 2016). The
ability of
Ethernet to scale easily (such as
quickly adapting to support new fiber optic cable speeds) is a contributing
factor to its
continued use.
CHARACTERISTICS
OF COMPUTER NETWORK:
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