INTRODUCTION TO COMPUTER NETWORKS
A set of devices often mentioned as nodes connected by media link is called a Network. A node can be a device which is capable of sending or receiving data generated by other nodes on the network like a computer, printer etc. These links connecting the devices are called Communication channels.
Computer network is a telecommunication channel using which we can share data with other computers or devices, connected to the same network. It is also called Data Network. The best example of computer network is Internet.
A network must be able to meet certain criteria’s, these are mentioned below:
i. Performance
ii. Reliability
iii. Scalability
Computer Networks: Performance
It can be measured in the 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 enquiry and response. Other ways to measure performance are:
• Efficiency of software
• Number of users
• Capability of connected hardware
Computer Networks: Reliability
It decides the frequency at which network failure take place. More the failures are, less is the network’s reliability.
Computer Networks: Security
It refers to the protection of data from any unauthorized user or access. While travelling through 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 a Good Network
1. Interpersonal Communication: We can communicate with each other efficiently and easily. Example: emails, chat rooms, video conferencing etc, all of these are possible because of computer networks.
2. Resources can be shared: We can share physical resources by making them available on a network such as printers, scanners etc.
3. Sharing files, data: Authorized users are allowed to share the files on the network.
USES OF COMPUTER NETWORKS
1. Computer Networks: Business Applications
Following are some business applications of computer networks:
i. Resource Sharing:
The goal is to make all programs, equipment’s (like printers etc.), and especially data, available to anyone on the network without regard to the physical location of the resource and the user.
ii. Server-Client model:
One can imagine a company’s information system as consisting of one or more databases and some employees who need to access it remotely. In this model, the data is stored on powerful computers called Servers. Often these are centrally housed and maintained by a system administrator. In contrast, the employees have simple machines, called Clients, on their desks, using which they access remote data.
iii. Communication Medium:
A computer network can provide a powerful communication medium among employees. Virtually every company that has two or more computers now has e-mail (electronic mail), which employees generally use for a great deal of daily communication
iv. eCommerce:
A goal that is starting to become more important in businesses is doing business with consumers over the Internet. Airlines, bookstores and music vendors have discovered that many customers like the convenience of shopping from home.
2. Computer Networks: Home Applications
Some of the most important uses of the Internet for home users are as follows:
• Access to remote information
• Person-to-person communication
• Interactive entertainment
• Electronic commerce
3. Computer Networks: Mobile Users
Mobile computers, such as notebook computers and Mobile phones, is one of the fastest-growing segments of the entire computer industry. Although wireless networking and mobile computing are often related, they are not identical, as the below figure shows.
