A computer network is a telecommunication channel through which we can share our data. It is also called data network. The best example of a computer network is Internet. Computer network does not mean a system with the control unit and other systems as its slave. It is called a distributed system
A network must be able to meet certain criteria, these are mentioned below:
- Performance
- Reliability
- Scalability
Performance
It can be measured in following ways:
- Transit time : It is the time taken to travel a message from one device to another.
- Response time : It is defined as the time elapsed between inquiry and response.
Other ways to measure performance are:
- Efficiency of software
- Number of users
- Capability of connected hardware
Reliability
It decides the frequency at which network failure take place. More the failures are, less is the network’s reliability.
Security
It refers to the protection of data from the unauthorized user or access. While traveling through the network, data passes many layers of network, and data can be traced if attempted. Hence security is also a very important characteristic for Networks.
Properties of Good Network
- Interpersonal Communication : We can communicate with each other efficiently and easily example emails, chat rooms, video conferencing etc.
- Resources can be shared : We can use the resources provided by network such as printers etc.
- Sharing files, data : Authorised users are allowed to share the files on the network.
Basic Communication Model
Communication model is used to exchange data between two parties. For example communication between a computer, server and telephone (through modem).
Source
Data to be transmitted is generated by this device, example: telephones, personal computers etc.
Transmitter
The data generated by the source system are not directly transmitted in the form they are generated. The transmitter transforms and encodes the information in such a form to produce electromagnetic waves or signals.
Transmission System
A transmission system can be a single transmission line or a complex network connecting source and destination.
Receiver
Receiver accepts the signal from the transmission system and converts it to a form which is easily managed by the destination device.
Destination
Destination receives the incoming data from the receiver.
Data Communication
The exchange of data between two devices through a transmission medium is Data Communication. The data is exchanged in the form of 0’s and 1’s. The transmission medium used is wire cable. For data communication to occur, the communication device must be part of a communication system. Data Communication has two types Local and Remote which are discussed below :
Local :
Local communication takes place when the communicating devices are in the same geographical area, same building, face-to-face between individuals etc.
Remote :
Remote communication takes place over a distance i.e. the devices are farther. Effectiveness of a Data Communication can be measured through the following features :
- Delivery : Delivery should be done to the correct destination.
- Timeliness : Delivery should be on time.
- Accuracy : Data delivered should be accurate.
Components of Data Communication
- Message : It is the information to be delivered.
- Sender : Sender is the person who is sending the message.
- Receiver : Receiver is the person to him the message is to be delivered.
- Medium : It is the medium through which message is to be sent for example modem.
- Protocol : These are some set of rules which govern data communication.