COMPUTER NETWORK HISTORY
The concept of
computer networks was born in the 1940s in America from a computer development
project MODEL I in Bell lab and Harvard University research group led by
professor H. Aiken. At first the project was just to use a computer device that must be shared. To do some process without wasting a lot of time is made a process batch
(Batch Processing), so some programs can run in a computer with the queue rules.
In the 1950s when the type of computer began
to enlarge until the creation of a super computer, then a computer must serve
multiple terminals. For that found the concept of time-based distribution
process known as TSS (Time Sharing System), then for the first time the form of
network (computer) applied. In TSS systems some terminals are connected in series to a host computer. In the process of TSS began to appear a fusion of computer technology and
telecommunications technology that originally developed separately.
Entering the 1970s, after the burden of work
increased and the price of large computer devices began to feel very expensive,
then begin to use the concept of distribution process (Distributed Processing). As in Figure 2, in this process several host computers work on a large
work in parallel to serve multiple terminals that are connected in series to
each host computer. Dala distribution process is absolutely necessary in-depth integration
between computer technology and telecommunications, because in addition to the
process that must be distributed, all host computers are required to serve its
terminals in a command from the central computer.
Furthermore, when the
prices of small computers have begun to decline and the concept of the
distribution process is mature, then the use of computers and networks have
started diverse from starting to handle the process together and communication
between computers (Peer to Peer System) just without going through the central
computer. For that began to develop local network technology known as LAN.
Similarly, when the Internet began to be introduced, then most of the
stand-alone LANs began to connect and formed a network of WAN giants.
TYPE
OF COMPUTER NETWORK
In general, computer
networks are divided into five types, namely;
1.
Local Area Network (LAN)
Local Area Network
(LAN), is a privately owned network within a building or campus measuring up to
several kilometers. LANs are often used to connect personal computers and
workstations within the office of a company or factories to share resources (eg
printers) and exchange information.
2.
Metropolitan Area Network (MAN)
Metropolitan Area
Network (MAN), is basically a larger LAN version and typically uses the same
technology as LAN. MAN may include adjacent company offices as well as a city
and can be utilized for personal (private) or public purposes. MAN is able to
support data and voice, can even be connected with cable television network.
3.
Wide Area Network (WAN)
Wide Area Network
(WAN), its reach covers a large geographical area, often including a country
and even a continent. WAN consists of a collection of machines that aim to run
user programs (applications).
4.
Internet
Actually there are many
networks in this world, often using different hardware and software. People who
connect to the network often expect to be able to communicate with other people
connected to other networks. Such desires require inter-network connections
that are often unsound and different.Usually to do this required a machine
called a gateway to make connections and implement the necessary translation,
both hardware and software. This collection of interconnected networks is what
is called the internet.
5.
Network Without Wires
Wireless network is a
solution to communication that can not be done with a network that uses cable.
For example, people who want to get information or communicate despite being on
a car or an airplane, the absolute wireless network is necessary because cable
connections are not possible in a car or plane. Nowadays wireless networks are
already rife in use by using satellite services and are able to provide faster
access speeds than wired networks.
TOPOLOGY
COMPUTER NETWORKS
Topology is a way of
connecting one computer with another computer to form a network. The most
widely used means are bus, token-ring, star and peer-to-peer network. Each of
these topologies has its own characteristics, with its own advantages and
disadvantages.
1.
BUS Topology
Bus topology shown in
the schematic above. There are advantages and disadvantages of this type:
Advantages:
Disadvantages:
- Save cable -
Detection and isolation error is very small
- Simple cable layout -
Traffic density
- Easy to develop - If
one client is damaged, then the network can not work.
- Remote repeater
required
2.
TokenRING Topology
TokenRING topology is
seen in the above scheme. The token-ring method (often called the ring only) is
a way of connecting the computer so that it is ring (circle). Each node has the
same level.The network will be called a loop, data is sent to each node and
each
the information
received by the node is checked for its address whether the data is for it or
not.There are advantages and disadvantages of this type:
Advantages:
Disadvantages:
- Cable savings - Error
sensitive
- Network development
is more rigid
3.
STAR topology
Is a centralized
control, all links must pass through the center that distributes the data to
all the nodes or clients it chooses. Central node called primary or server
stratum and other called secondary station or client server. Once the network
connection is started by the server then each client server at any time can use
the network connection without waiting for commands from the server. There are
advantages and disadvantages of this type:
Advantages:
- Most flexible
- Installation / change
station is very easy and does not disturb other parts of the network
- Centralized control
- Ease of detection and
isolation of errors / damage
- Ease of network
management
Loss:
- Wired waste
- Need special handling
- Centralized control
(HUB) is a critical element
4. Peer-to-peer Network
topology
Peer means co-worker.
Peer-to-peer network is a computer network consisting of several computers
(usually no more than 10 computers with 1-2 printers). In this network system
the priority is the use of programs, data and printers simultaneously. Computer
user named Dona can use the program installed on Dino's computer, and they can
both print to the same printer at the same time.
This network system can
also be used at home. Computer users who have 'old-fashioned' computers, such
as AT, and want to buy a new computer, say Pentium II, no need to throw away
old computers. He simply installed a netword card on both computers and then
connected with a special cable used for network systems. Compared with the
above three ways, this network system is simpler so it is easier to learn and
use.