Thursday, July 21, 2011

Communication Data and Computer Networks

  1. Computer Networking
The computer network is a collection of computers, printers and other devices are connected in one unit. Every computer printer or peripherals connected to the network are called nodes.
In general, a computer network is divided into five types, namely:
1. Local Area Network (LAN), a privately owned network within a building or campus-sized to several kilometers.
2. Metropolitan Area Network (MAN), is basically a LAN version is larger and usually use the same technology as the LAN. MAN can include corporate offices are adjacent or also a town.
3. Wide Area Network (WAN), mecakup reach a wide geographical area, often covering a country or even continent. WAN consists of a collection of machines that aim to run the programs (applications) user.
4. Internet, basically the Internet is a collection of interconnected networks. This happens because people are connected to the network often expect to be able to communicate with others who connect other network. To do this requires a machine called the gateway to engage and implement the necessary translation, both hardware and software.
5. Wireless Networking, a solution to communication that can not be done with a wired network.

Computer Network Topology
Topology is a way of connecting one computer to another computer so that form a network. Way that is currently widely used is the bus, token-ring, and star. Each has a characteristic topology, with the advantages and disadvantages.
1. Bus Topology
Profit ;
• Save cables
• Simple wiring layout
• Easy to develop
• Detection and isolation of error is very small
• Density of traffic
• If one client is damaged, then the network could not function.
• Required repeater for long distance

2. Token Ring Topology
Token-ring method (often called a ring anyway) is how to connect computers so shaped ring (circle). Each node has the same degree. Network will be called as a loop, data is sent kesetiap node and any information received by the node address is checked whether the data for him or not.
• Save Cables
• Be sensitive to errors

• Developing a network of more rigid
3. Star Topology
Centralized control, all links must pass through the channel center all of the data node or the client chooses. Central node is called a primary station or server and ainnya called secondary stations or client server. Once the network connection initiated by the server, each client server at any time can use a network connection without waiting for commands from the server.

• Most flexible
• Installation of the station is very easy and does not interfere with other parts of the network
• Centralized Control
• Ease of detection and fault isolation / damage
• ease of network management

• Cable Boros
• Need special handling
• Centralized Control (HUB) be a critical element
  1. Data Communications
Data communication is part of telecommunications that are specifically related to the transmission or transfer of data and information among computers and other devices in digital form that is sent through a data communications medium. Data means information that is presented by the digital signal.

Data Communication Components
  1. Conductor / sender, is any device that sends data
  2. Recipient, is any device that receives data
  3. Data is information that will be moved
  4. Media delivery, is a medium or channel used to transmit data
  5. Protocol, is the rules that serve to harmonize the relationship

A protocol is a rule that defines some functions that exist in a computer network, such as sending messages, data, information and other functions that must be met by the sender and receiver side so that communication can take place properly, although the existing system in the different networks together once.

The popular standard protocols OSI (Open Systems Interconnecting) specified by ISO (International Standard Organization).
The function of the protocol is to connect the sender and receiver side in communicating and exchanging information in order to run properly and correctly.
Consist of 7 layers (layers) which defines the function. For each layernya may consist of a number of different protocols, each providing service for which the function of that layer.
1. Application Layer
2. Presentation Layer
3. Session Layer
4. Transport Layer
5. Network Layer
6. Data-link Layer
7. Physical Layer

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