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					Essential communication systems and computer networks.

      Network (Network System) refers to a computer from two or more.
Together, such as connecting computers within classrooms within the building,
between the towns.
And thus to the connected computers around the world called. "The Internet"
      In the present communication has its roots in an attempt to connect to
the computer.
Together with a computer-based communication systems. Later, when the
computer more and more demand.
Contacts between multiple computers at the same time the network (Network

      Office automation systems (Office Automation System) is a method of
That their application is being used in the office. The system. Personnel to
work at least through.
Automated tools to link information and communication systems. The tools

     Office is an office automation is the key element.

Networking System is a network that links between computer systems across
the enterprise.

Electronic Data Interchange is to communicate information between each
other. Based on the information.
Via electronic networks.

Internet Working together is the network that spreads across the globe. Into a
larger network.
Paperless System is a system that no longer plays an important role in the
paper is to provide information.

The advantage of data communications.

1. Store information easily and quickly communicate.

2. The accuracy of the information.

3. The speed of operation.

4. Cost-effective.

Standard for computer networking.

         The office is required to exchange data between them. Each desk is.
As one point of the analysis process to identify the information and send it to
other tables. Or to other units.
The result is a network of processing. Or multiple computers plugged into the
With the office automation system, it is processed in various points and then
send information to each other via
Computer networks.

       Reasons for networking computers together. The price of the computers
were down.
And to increase the capacity of the system as a whole. The computer
equipment alone.
I work in one. However, when combined, will run up and can share resources
and exchange.
Information between them.

       Transmission of data between computers on the network. Need to have
a central computer.
All brands and models of equipment or systems can be linked together.
Network. Will be implemented.
Various tasks such as data transmission. Access to the network. Printing by
using the network.

       With international standards organization that has set the standard for
the connection.
Open communication (Open Systems Interconnection: OSI), which is the
standard used to transmit data.
Between any two terminals on the network communication systems. Are
divided into levels (Layer) has seven levels, but
Each level will have to set the standard in its own dealings. And one dealing
with the same level.
One of the other end. Higher level of orders received and processed at a lower
level than necessary.
Need to know the details of the lower level.

       Communication in different levels will require the control to the system
is properly
Standards by communicating data packets. Will involve three levels including
the bottom.

1. The level of physical (Physical Layer) level is associated with the data a bit.
Associated with.
Voltage range of periods.
2. Datalink (Data Link Layer) is the conversion of the data transmission. With
Indeed given up. The data is formatted as a block like frame (Frame), with error
3. Entewarsc level (Network Layer) to transmit data packets to the Entewarsc
They may travel freely. The mailing address of the recipient and sender of this
method is called Datagrame.

       Currently, there are many Internet users around the world. Each is a
different computer models.
The communication between a computer language that will require a
compatible computer.
The language is known technically as the "Protocol" (Protocol) protocol
standard used in
Communication on the Internet is called TCP / IP, which is prevalent
throughout the world with a network.
Internet protocol is getting very popular nowadays.

       The TCP / IP protocol will be sent to the computer's other parts.
(Called packets: packet) and sends it to the Internet. The distribution of those
Many of the routes to be combined at the destination. And bring together a
complete data again.

       A working model of the TCP / IP protocol that is divided and sub-section
delivery can help.
Prevent errors that may occur in the communication. If the information. Is a
partial loss.
Is not all lost. The destination computer can be. Detection of the lost data and
The source computer sends only the data that was lost again.

      TCP / IP protocol was invented by the U.S. government and is used to
prevent peer computer networks.
Damage that may occur as in the case of the computer center in the state for
one attack taking place.
Damage the computer network of the rest, it can also be connected together.
Because the data is transferred along the line.
Another way, the network instead.

The definition of a computer network.
       Computer networks (Computer Network) is a group of computers and
computer equipment.
Which are interconnected through communication or any other media. Users
in the network can communicate.
Exchange and use of various network devices together.

       The role of computer networks. And increasingly important because of
the microcomputer has been used.
Widely. Hence the need to connect those computers together. To increase the
capacity of the system.
Gave rise to various applications and reduce overall system cost. Network is
small and interconnected with
Computer only a couple of machines for use in the home. Or in small firms. To
the global network to cover.
Almost all countries. The network can connect as many computers around the
world together, we call it. Internet.

The structure of a computer network.

1. Local network (Local Area Network: LAN).
2. The city network. (Metropolitan Area Network: MAN).
3. Wide Area Network (Wide Area Network: WAN.
Close-up computer network connections.

         If you want to put a personal computer connected to the system.
Using existing capabilities.
That is how easy it can be done as follows.

1. Connected via Com1, Com2 and LPT is a computer that is connected through
the channel.
The COM1 or COM2 in order to move data between them.
2. Connected to the printer buffer. To share the printer to make use of
Printers (Printer) for more benefits.
3. The switch to using the data cable. As a way to extend a helping hand with a
simple to use.
Switch acts like a telephone information line.
4. Connect multiple users via multiple channels. Many users of small systems.
On the microprocessor.
There are many computer systems such as UNIX, Linux systems can be
connected to the substation.
Many systems are sharing the cost.

The Computer Network (Network Topology).

        Network Bus (Bus Network) is a network that connects computers and
other devices.
The cable is long so it has a connector to connect to a computer. And the
device to the cable.
Cable to transmit data to a computer that can transmit data only in a certain
period of time.

        Network Star (Star Network) is a network-connected computer. The
device is.
The center of the network by bringing together the various stations with the
central switch. Communication between stations.
Be made by contacting the circuit of the switch. Function of the central switch.
The central
Of the interface circuitry between the various stations to communicate with
each other.

         Network Ring (Ring Network) is a network connection. With a
computer and Noble.
Long line in the ring. Traffic on the network ring. It uses only one direction.
When the computer.
One send it to the next computer. If the information received does not match
the source computers.
A computer will pass to the next step will be. This repeatedly until it reaches
the destination computer.
Identified by an address from the source.

         Network tree (Tree Network) is a network with a mix of various
network structures.
Into a larger network. The data can be sent to all stations. Communication is
via an intermediary.
To all the other stations because the stations are located on the link. Transfer
the same data.

Elements of the network include

Hardware (Hardware).

PC (Client Computer).
Servers (Server).
Hub (Hub).
Bridge (Bridge).
Router (Router).
Gateway (Gateway).
Modem (Modem).
Network Card (Network Card).
Software (Software).

Network operating system (Network Operating Sytems).
Application of the network (Network Application Sytems).
Carries the information (Media Transmission).

         Transmission line or Cable Network is one in which the passage of
Between Workstation and Server are similar to cable or telephone lines, but
the choice depends on the type of Cable.
Cable should pay attention to safety (Safety) and noise. (Interference), it is
essential that the data transmission.
Should not be a conductor of light, fire and prevent interference of magnetism.
And radio.
The transmission of information. Divided as follows.

Coaxial Cable Coax cables or wires can also be used in the Network. Applied to
the system.
Mainframe with cable TV and Coax cable is comprised of the core. And
insulated copper wire.
(The spray) a layer of insulated. In a change from copper wire to wire money to
several thousand.
Lines to prevent interference of the so-called "Cross Talk", a signal interference
caused side effects.

Twisted Pair Cable is the cable signal transmission line consists of two copper
wires twisted to a spiral.
(Twist) and insulated, divided into two types with the Shield and the Shield will
have no insulation in the.
Shielding. Or prevent interference by the Cable line is that both "Shielded
Twisted Pair (STP)" and "Unshielded Twisted Pair (UTP)".

Cable Shielded Twisted Pair (STP), also known as. "Twisted pair of insulated," a
Twist the insulated outer layer of thickness. To prevent interference of the
waves. Electromagnet

Cable Unshielded Twisted Pair (UTP), also known as. "Twisted pair cable. Are
not insulated. "
Twisted pair cable is insulated with a thin outer layer, making it easy to bend
the wire with an inexpensive UTP cabling.
And easy to find, but the shielding. Not as good as the STP.

Cable Fiber Optic Cable is a new type of optical fiber. The glass tube. Small and
Called "CORE" is surrounded by a layer of glass fiber, called "CLADDING" Data
transfer rates up to 565 megabits per second or more shielding is very good.
The size of a small and lightweight, but expensive.
     In addition to various forms of data communication lines, then the data is
sent wirelessly (Wireless Transmission).
This data transmission through the atmosphere without any signs, such as
microwave, satellite communications systems.
Mobile phones, which are electromagnetic signals with different frequencies.
Make communication faster.
And covering all corners of the world.

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