Computer Network

Computer network is a system consisting of computers and other network devices that work together to achieve a common goal. The purpose of the computer network are:

•  Sharing of resources: for example, shared use of printers, CPUs, memory, hard drive
•  Communication: eg electronic mail, instant messaging, chat
•  Access to information: for example web browsing

In order to achieve the same goal, each part of the computer network and provide service request (service). Party requesting the service is called a client (client) and that provide services called the servant (the server). This architecture is called client-server systems, and is used in almost all computer network applications.

Classification Based on the scale:

•      Personal Area Network (PAN)
•      Campus Area Network (CAN)
•      Local Area Network (LAN): a computer network that connects a computer with another computer with a limited distance.
•      Metropolitant Area Network (MAN): principle the same as LAN, only the larger distance, ie 10-50 km.
•      Wide Area Network (WAN): the distance between cities, countries, and continents. This is the same with the Internet.
•      Global Area Network (GAN)

Based on the function: Basically every computer network is functioning as a client and server. But there is a network that has a dedicated computer as a server and the other as a client. There is also a computer that has no special function as a server only. Therefore, based on their function there are two types of computer networks:

     * Client-server

Network is the computer with a dedicated computer as a server. A service / service can be provided by a computer or more. An example is a domain like www.detik.com lots served by the web server computer. Or it could be a lot of service / services provided by a single computer. Examples are jtk.polban.ac.id server that is a multi-service computer with the mail servers, web servers, file servers, database servers and others.

     * Peer-to-peer

Namely computer networks where each host can be a server and also a client simultaneously. For example in the file sharing between computers on the Windows Network Neighborhood Network have 5 computers (we give the name of A, B, C, D and E) that provide access rights to the files they have. At one point A to access the file share of B named data_nilai.xls and also gives access to the file soal_uas.doc C. When accessing a file from B then A serves as a client and as a give file access to C then A serves as a server. Both functions were performed by the same A network like this is called peer to peer.