Computer network is a system consisting of computers, software and other network devices that work together to achieve a common purpose. The purpose of the computer network are:
* Sharing of resources: for example, shared usage of the printer, CPU, 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 to request and provide services (service). Parties who request / receive services is called a client (client) and which give / send a service called the waiter (server). This architecture is called client-server system, and used in almost all computer network applications. [Edit] Classification
Based on the scale:
* Local Area Network (LAN): a computer network that connects a computer with another computer with a limited distance.
* Metropolitant Area Network (MAN): the same principle with the LAN, only the distance is larger, ie 10-50 km.
* Wide Area Network (WAN): the distance between cities, countries, and continents. This is the same with the Internet.
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 while the other as a client. There also are no special computer to function as a server only. Therefore, based on its function then there are two types of computer networks:
* Client-server
That is a computer network with a dedicated computer as a server. A service / service can be provided by a computer or more. An example is a domain such as www.detik.com served by many web server computer. Or it could be a lot of service / services provided by a single computer. Examples are jtk.polban.ac.id servers that constitute a computer with a multi-service namely mail server, 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 file sharing between computers on the Network Windows Network Neighbourhood there are 5 computers (we named A, B, C, D and E) that gives the right of access to the files they have. At one point A from B to access a file share named data_nilai.xls and also gives access to the files soal_uas.doc C. When A access the files from B then A serves as a client and when A gives access to the file C then A serves as a server. Both functions were performed by A at the same time, the network like this is called peer to peer.
Based on network topology, computer networks can be divided into:
* Bus Topology
* Topology star
* Ring topology
* Mesh topology
* Topology tree
* Linear Topology
Based on the criteria, computer networks can be divided into four namely:
1. Based on the distribution of sources of information / data
* Centralized Network
This network consists of client and server computer where the client computer that serves as an intermediary to access sources of information / data derived from a single computer server
* Distributed Network
Is a mix of some centralized network so that there are several computer servers that are interconnected with the client to form a specific network system.
2. Based on geographic coverage can be divided into:
* LAN Network
is the tissue that connects 2 computers or more in coverage such as laboratories, offices, and in a cafe.
* Network MAN
Is a network that covers a large city and its local area. Examples of local telephone networks, cellular telephone systems, as well as relay some ISP Internet network.
* Network WAN
Is a network with coverage throughout the world. An example network of PT Telkom, PT. Indosat, as well as networks such as GSM Cellular Satelindo, Telkomsel, and much more.
3. Based on the role and relationship of each computer in data processing.
* Client-Server Networks
In this network there are 1 or more server computers and client computers. Computers that will be a computer server or a client computer and can be switched through the network software protocol. The client computer as an intermediary to be able to access data on a server computer while the computer server providing the information required by the client computer.
* Network Peer-to-peer
In this network there are no client computer and server computer because all computers can perform transmission and reception of information so that all computers function as clients as well as the server.
4. Based on data transmission media
* Wired Network (Wired Network)
In this network, to connect one computer to another computer takes the form of cable connecting the network. Network cable to function within sends information in the form of electrical signals between the network computer.
* Wireless Network (WI-FI)
Is a network with medium in the form of electromagnetic waves. In this network is not required cable to connect between computers because it uses electromagnetic waves which will transmit signals between a computer information network.
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