We have studied the concept of networks as well as a worldwide computer network called the Internet. In this chapter, we will study the interesting and important topic of computer networking. We all use telephones for talking to each other and for conveying information quickly. Telephones are located all over the world and are conveying information. By one another by one or the other mean of communication.
Telephones all over the world form a telephone network. Similarly, computer networking is the process of creating a network of computers and computer devices by linking them to one another for accessing and sharing resources. Let us now study the advantages of computer networking.
- Computer networking allows the sharing of costly resources. For example, one costly color laser printer can be shared by all the computers on the computer network in an office.
- It also allows access to and timely updation of critical databases used by a large number of users at different locations at a time.
Examples – railways and airline reservation systems.
Now, we will discuss some important and basic networking terms.
Medium: The physical medium or communication channel which is used for information transfer among computers. Examples: Twisted wires, Co-axial cables, Optical fiber cables, and microwave and satellite communication.
Server: A Server is a powerful computer that has a fast processor, large memory storage and special server software, etc. It provides some services or resources to other computers known as clients.
Client: A Client is a computer that accesses the services or shared resources on a network provided by the server.
Hub: A Hub is a central hardware device in a network that manages traffic across the network. A hub divides the bandwidth or communication speed equally among the computers connected thereto.
Switch: A Switch is a central hardware device that manages the flow of information among the PCs and devices connected to it. The rate of flow of information is linked to the speeds backed up by the switch and the devices.
NIC: More commonly referred to as a LAN card, the network interface card is a hardware device that enables a computer to connect to a network and send/receive data.
Network Peripherals: Network Peripherals are computer peripherals that are either connected to the network’s hub or switch by a suitable connector and cable.
Examples are – plotter, scanner and Printer.
Network Operating system: it is an Operating system required by all the computers on the network. NOS makes the network work by coordinating, enabling services, and sharing resources among the networking computer.
Examples are – Microsoft Windows NT, Windows 98, 2000, Windows XP, and Novell Netware.
Router: It is a network hardware device that is used in WAN (Wide Area Network) for routing data across the different parts of a network.
Protocol: It is a set of defined standard procedures that govern how data is transferred among computers on a network.
Example – TCP/IP (transmission Control Protocol/Internet Protocol).
TYPES OF NETWORKS
Computer networks are designed to meet some particular requirement and cover small or large distances a computer network in an organization can connect the entire computer in a building, in this offices all over a county or all over the world.
Based on the distances covered by the computer networks, they are classified into three types – LAN, MAN, and WAN.
LAN refers to Local Area Network. This covers a small area, typically an office or a building. The PCs and the network peripherals mostly use copper wires or wireless links for communication. As all the PCs are located in a building, the speed of communication is good and the communication errors and data loss is less. The cost of setting up a LAN is low as compared to the larger networks.
MAN refers to Metropolitan Area Network. It covers a metro or a city. A Metropolitan Area Network is used by an organization that has offices across a metro city. The cost of setting up a Man is more than that of setting up a LAN. MAN can be compared to a Cable TB Network.
WAN refers to Wide Area Network. WAN spreads across different cities or countries. These networks are used by large organizations and use one or more communication media such as leased lines, radio waves, fiber optic cables, and satellites. WAN can be compared to the Automated Teller Machine (ATM) network.
Another classification of computer networks based on the target users and the information content distinguishes networks as Internet and Internet.
Intra means within, thus the Internet means within a network. Internet is a network within a particular organization with some general as well as confidential information. This information is distributed in the form of web pages meant only for employees or internal users of an organization.
For example, an organization may have an Internet, where it gives information to its employees on organization policies, open discussion topics, forms, training material, etc.
Internet is made of words – Inter and Net which mean between networks. Internet is a network of worldwide computers that can share information with one another. Internet has servers of organizations, governments, educational institutions, business companies or an individual connected with one another and is open for public use. As compared to the Internet, the Internet provides more benefits and its coverage is more widespread.
Some big organizations have separate servers and network hardware for their Internet setups. Employees of the organization can access confidential information from their Company Intranet whereas the general public can access general information about the organization from the Internet.
CLILENT – SERVER NETWORKS, PEER-TO-PEER NETWORKS
On the basis of hardware and software usage, computer networks are classified into two types – Client-Server Networks, Peer-to-peer Networks.
CLIENT – SERVER NETWORKS
Client-Server networks have a server for providing some specific applications and services to network clients. There can be multiple servers, with each server providing a specific service or a single server providing various services.
A computer network with a geographical coverage may use multiple servers whereas a network with a smaller geographical coverage may use a signal server. A Client-Server based network is more common and mostly used in Computer Networks. Some examples of the services provided by Servers in Client-Server Networks are:
Authentication Servers: Verify the usernames and the passwords of the users logging into the network.
File and Print Servers: Manage user’s access to resources like files and printers.
Application Servers: Provide users access to applications based on the rights allotted to them.
Mail Servers: Provide authentication of mail users, manage their mailboxes, and routing of the messages to and from other mail users
Peer-to-Peer networks have computers that are equal in terms of their local resources and can work as a server and a client when required. Peer-to-Peer networks should be used when-
- There is a small number of users.
- The network coverage area is less, i.e., within an office or a building.
- The future expansion of the network is not expected.
- Security is not a critical factor in the network.
- Only a simple network setup and administration is required.