02-05-2011, 12:37 PM
PRESENTED BY:
NASEEM AHMED KHAN
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DATA COMMUNICATION
Data Communications is the transfer of data or information between a source and a receiver. The source transmits the data and the receiver receives it.
Or
The transmission of data from one computer to another, or from one device to another.
The five components of Data Communication System
The five components are :
1. Message - It is the information to be communicated. Popular forms of information include text, pictures, audio, video etc.
2. Sender - It is the device which sends the data messages. It can be a computer, workstation, telephone handset etc.
3. Receiver - It is the device which receives the data messages. It can be a computer, workstation, telephone handset etc.
4. Transmission Medium - It is the physical path by which a message travels from sender to receiver. Some examples include twisted-pair wire, coaxial cable, radiowaves etc.
5. Protocol - It is a set of rules that governs the data communications. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating.
Data Transfer Rate
The speed with which data can be transmitted from one device to another. Data transmission speeds are usually given in bits per second, or bytes per second. For fast connections, this is sometimes expressed as kilobits ,megabits (million bits) or megabytes (million bytes) per second. These are usually abbreviated as Mbps and MBps, respectively.
Computer Networking
Computer networking is the engineering discipline concerned with the communication between computer systems or devices.
Or
A computer network is any set of computers or devices connected to each other with the ability to exchange data
Introduction to Network Types
Common examples of area network types are:
LAN - Local Area Network
WAN - Wide Area Network
Wireless networks (WLAN, WWAN)
MAN - Metropolitan Area Network
LAN - Local Area Network
A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room).
WAN - Wide Area Network
As the term implies, a WAN spans a large physical distance. The Internet is the largest WAN, spanning the Earth.
A WAN is a geographically-dispersed collection of LANs. A network device called a router connects LANs to a WAN.
An example of this is a multinational business that uses a WAN to interconnect their offices in different countries.
Wireless Networks (WLAN, WWAN)
A wireless network is basically the same as a LAN or a WAN but there are no wires between hosts and servers. The data is transferred over sets of radio transceivers (a transmitter and receiver combined in one unit). These types of networks are beneficial when it is too costly or inconvenient to run the necessary cables.
Metropolitan Area Network
A network spanning a physical area larger than a LAN but smaller than a WAN, such as a city. A MAN is typically owned an operated by a single entity such as a government body or large corporation.
Network Topology
A network topology describes the layout of the wire and devices as well as the paths used by data transmissions.
Types of Network Topologies
Network topologies are categorized into the following basic types:
BUS
RING
STAR
Bus Topology:
Bus topology is one the easiest topologies to install, it does not require lots of cabling.
Bus topology uses one common cable (backbone) to connect all devices in the network in linear shape.
In this type of network topology, all the nodes of a network are connected to a common transmission medium having two endpoints.
Bus topology is easy to handle and implement and is best suited for small networks
Ring Topology: Ring topology is one of the old ways of building computer network design
In ring network topology computers and other networking devices are attached to each other in such a way that they have devices adjacent to each other (Left and right side).
All messages are travelled in the same directory either clockwise or anticlockwise.
In case of failure of any device or cable the whole network will be down and communication will not be possible.
Ring diagram
Star Topology: This is the most commonly used network topology design you will come across in LAN computer networks. In Star, all computers are connected to central device called hub, router or switches using Unshielded Twisted Pair (UTP) or Shielded Twisted Pair cables.
GATEWAY
A gateway is a network point that acts as an entrance to another network
A gateway is a combination of hardware and software that translates between two different protocols and acts as the connection point to the Internet.
A very popular example is connecting a Local Area Network or Wireless LAN to the Internet or other Wide Area Network. In this case the gateway connects a LAN to the provider-specific network which in turn connects to the Internet.
