The need for the computers is increasing day by day. Every person is becoming dependent on computers. If each person having computer has separate auxiliary devices then the cost of operating computers would increase, so to overcome this cost, resource sharing is required. Moreover, the need for faster means of communications between different computers is also arising. So to solve all these problems we have computer networks. In a computer network different devices are being shared by different computers connected over the network. Moreover, the communication of computer help us to share important information.
To maintain the computer network we need both the hardware devices and the software. The most common hardware media for data communication are twisted-pair cables, coaxial fibre, fibre-optics cable and wireless links. The various softwares which help the various nodes over the network of communication are called network operating systems. Some common network operating systems are Windows 95, Windows 2000, Novel Netware and Banyan Vines.
What is Networking ?
In the world of computers, networking is a practice of linking two or more computing devices together in order to share resources, exchange files or allow electronic communication.
Networking involves designing, implementing, upgrading, managing the computer networks. Computer Networking is a discipline concerned with communication between computer systems. It involves at least two computers capable of being networked with each other.
Computer Networks:
Computers have become an integral part of every organization. These computers may be located at different locations within building/campus/organization. Each computer may perform different set of tasks and may work in a different environment without interacting with each other. This may result in overlapping of some tasks/work of computations. If computers are connected by a network, many of the overlapping tasks will be minimized and we will be able to extract the information from each computer and share the existing information.
Computer Network is a collection of interconnected independent computers and peripherals connected by communication facilities for exchanging information and sharing resources. A computer network can be anything ranging from two interconnected computers to thousands of interconnected computers. In our definition, by the term independent we mean that there is no master/slave relationship between the computers i.e. computers behave independently without forcible control. For example – a central computer with time sharing terminal and shared memory multiprocessor are not computer networks. The connection between the computers can be permanent via cables or temporary through telephone line or other communication links.
An important feature of modern computer networks is Network transparency. By this we mean that a user can access resources without need to know whether resources are located on local machine that is the one user is currently using a remote machine that is a computer else where on the network.
Computers are used for different purposes. We use various types of networks everyday. Each time we use a credit card, get cash from ATM machine, we are using some type of a network. The basic reasons for using computer networking are :
- To share resources such as file printers, disk storage, scanners, CPU
- To share application software like accounting software
- To exchange information such as email, message documents
- To have communication such as chatting, on-line meeting
Let us consider an example of an office the need for a Computer Network. We assume that the office has twenty computers and two printers each connected to a computer. There are eighteen users who can’t print directly from their desk except those whose computers are directly connected to printer. Any user who wants to take printout has to save his work on some portable media like floppy disk or CD-ROM etc and carry the storage media to the computer to which printer is attached. But if computers are networked each user will be able to print to any of the two printers and share other computer’s resources like scanners, softwares, storage space etc. Thus it results in saving time and cost.
Computer Networks allow users to access remote programs and remote databases either of the same organization or from other enterprises. Computer Networking provide communication facility faster than other ways of communication.
Network Criteria:
It should meet the follow criteria to be efficient and effective –
- Performance
- Reliability
- Recovery
- Consistency
- Security
These are explained as below –
1. Performance – The performance of a network is the rate of transfer of error free data. It is measured by response time which is the time gap between sending a request and getting a response. In order to have a better performance, the response time of a network should be small. In other words, performance and response time are inversely related to each other. The network that does not offer adequate performance will not perform the job properly for which it is designed. Its performance depend on following factors :
- Type Of Transmission Media
The transmission media determines the speed at which data can travel. For example – Optical fibre offers better transmission speed as compared with coaxial/twisted pair cable. If other factors that effect the performance are the same then a network using the optical fibre as the transmission media will be better than network using coaxial/twisted pair cable as the transmission media. - Hardware And Software
The hardware used in the networking effect the transmission speed. For example – a network with high speed computers provide better performance as compared with low speed computers. The software in network provides various services like transmitting a message from one node to another, ensuring error free delivery etc. A well designed software will provide better services. So a network using well designed software as NOS (Network Operating System) improves its performance. - Number Of Users
The number of users effect its performance. More is the number of users slower will be the network.
2. Reliability – Reliability is measured by the frequency of failure i.e. how often a network fails which may be due to failure of hardware, NOS.
3. Consistency – Consistency is the predictability of response time and accuracy of data. The accuracy of data determines if the network is reliable or not. If a system loses data then user will not have confidence in the information and user will not prefer to use such system.
4. Recovery – Recovery is network’s ability to return to prescribed level of operation after network failure. This level is where amount of lost data is zero/minimum. Recovery tells how quickly a network recovers from failure.
5. Security – Security refers to protecting network resources against unauthorized access and viruses. A network should be secured by providing various techniques like password, encryption techniques and antivirus programs etc.