Thursday, August 7, 2008


A. Preliminary
Computer networks is not something new today. Almost in every company there is a computer network to facilitate information flow within the company. Internet is gaining popularity today is a giant computer network which is a network of computers connected and can interact with each other. This can happen because of the development of network technologies very rapidly, so that within a few years the number of users of computer networks belonging to the Internet doubled.

B. Computer Networking
1. Definition
Computer network is a collection of computers, printers and other equipment are connected. Information and data moves through the wires to allow users of computer networks can exchange documents and data, print on the same printer and share the hardware / software that connects to the network. Each computer, printer or peripherals that connect denganjaringan called nodes. A computer network can have two, tens, thousands or even millions of nodes. A network typically consists of 2 or more computers that are interconnected among each other, and share resources such as CD-ROM, printers, exchange files, or the ability to electronically communicate with each other. Computers that connect those, made possible with the media cables, telephone lines, radio waves, satellite, or infrared rays.

2. Network Types
There are 3 kinds of Networks / Network are:

a. Local Area Network (LAN) / Local Area Network.
A LAN is a network that is limited by a relatively small area, generally bounded by the area like an office environment in a building, or a school, and usually not far from about 1 km square. Several models of LAN configuration, one computer is usually made in a file server. Which is used to store software (software) that regulate network activity, or as software that can be used by komputerkomputer that is connected to the network. The computers are connected to the network (network) is usually called a workstation. Usually workstation capabilities over the bottom of the file server and have other applications on the hard drive in addition to applications for the network. Most LANs use the media cable for connecting between one computer to another computer.

b. Metropolitan Area Network (MAN) / Metropolitan area network

A MAN, usually covering a larger area than a LAN, for example between regions within a province. In this case the network connecting several small networks into larger areas of environment, for example as follows: Bank network in which several branches of a bank in a big city is connected between each other. For example, Bank BNI in the entire region or Surabaya Ujung Pandang.

c. Wide Area Network (WAN) / Large Scale area network

Wide Area Networks (WAN) is a network that already use a scope usually means satellite or submarine cable as an example of the whole network BANK BNI in Indonesia or in other countries. Using the WAN facilities, a bank in Bandung can contact its branch offices in Hong Kong, just a few minutes. WAN usually rather complicated and very complex, using many means to connect between LAN and WAN to the Global Communications such as the Internet. But somehow between LAN, MAN and WAN are not much different in some respects, only the scope of the area is just a different one among others.

3. Protocol

Protocol is a set of rules that govern communications between computers on a network, the rules include guidelines that apply to the ways or methods of accessing a network, physical topology, the types of cable and data transfer speeds.

Protocols supported are as follows:
1. Ethernet
2. Local Talk
3. Token Ring
5. ATM


Ethernet protocol is by far the most widely used, the Ethernet access method called CSMA / CD (Carrier Sense Multiple Access / Collision Detection). This is a system where each computer listens to the cable network before sending anything into it. If the network is clear, the computer will transmit the data, if there is another transmission on the cable, the computer will wait and will try to re-transmission if the network has been clean. Sometimes, two computers transmit at the same time, when this happens, each computer will be back and will wait a random chance to transmit data back. This method is known to the coalition, and will not affect the speed of transmission on the network.

The Ethernet protocol allows for linear bus, star, or tree. Data can be transmitted over twisted pair cable, coaxial, or fiber optic cable at speeds of 10 Mbps.