THE CONCEPT OF NETWORKING

 

The idea of networking is probably as old as telecommunications itself. Nowadays, we have computer talking to each other over vast assemblages of wires, fiber optics, microwaves etc. in this lesson we would be dealing with the means and ways by which the process of communication is accomplished through computers.

 

We can define network as a collection of computers that are able to com- municate with each other, often by relying on the services of a number of dedicated hosts that transmit data between the participants. Hosts are very often computers but one can also think of intelligent printers as hosts. Small agglomerations of hosts are also called sites.

 

EVOLUTION OF COMPUTER NETWORKS

 

Apart form the centralized computing paradigm dominated by monolith mainframes until late 1970 s, the initial use of modern networks was for file and print services in academic environments. With these services users could access files remotely from a file server and send print requests to a remote printer controlled by a dedicated machine called print server

 

Gradually the utility of these network services started getting appreciated- d in commercial environments and small offices and later large offices started setting up networks for file and print services. Soon networks were also being used for application services so that applications could be loaded on the user machine from a dedicated machine called application server.

 

With the falling prices of small computers and PCs, system designers started using these small machines to build large low-cost networks based on what is called client-server architecture. In this, the user machines are called clients and the are served by dedicated machines called servers.

 

ADVANTAGES OF NETWORKING

There are many advantages offered by networking. some of them are as follows:

 

• Resource Sharing

 

The main advantage of the networking is that it enables resource sharing which is of a great advantage to the organizations in particular. The primary goal of networking is to make all programs, equipment, and especially data available to anyone on the network without regard to the physical location of the resource and the user. In other words, the mere fact that a user happens to be 1000 km away from his data should not prevent him from using the data.

 

• High Reliability

 

High reliability is provided by networking by having alternate sources of supply. For example, all files could be replicated on two or three floppies or machines in the sense that if one copy has some problem the other can be used accordingly. For military, banking, air traffic control, and many other applications, the ability to continue operating in the face of hard ware problems is another hard disk can rescue the people in such areas from unnecessary trouble.

 

• Saving Money

Today most of the networks consist mainly of smaller computers rather than the large mainframes, which used to be the concept in earlier days. this is so because small computers have a much better price/performance ratio than large ones. The mainframes are roughly a factor of ten faster than Personal Computers (PCs), but they cost a thousand times more. This imbalance has caused many system designers to build systems consisting of personal computers giving rise to the concept of one computer per user, with data kept on one or more shared file server machines. The whole arrangement is based on the client-server model.

 

• Scalability

Another advantage offers by networking is scalability. This can be defined as the ability of the network to increase system performance gradually as the workload grows just by adding more processors.

This scalability becomes much easier in case of the smaller computers. This is so because in case of centralized mainframes, when the system becomes full, it is replaced by a larger one, usually at great expenses and even causing disruption to the users. With the new client-server networking model, mew clients can be added as needed as and whenever needed without causing mush disruption and inconvenience to the users.

 

• Communication Medium

 

A computer network acts as a powerful communication medium among widely separated people. Today a network has the ability to connect two or more people placed remotely apart form each other.

 

In the future, the advantage of network to enhance human-to-human communication will probably prove more important than technical goals such as improved reliability. Today the popularity of the internet shows how important is networking in the communication between the remotely placed people.

 

• Access To Remote Information

 

Starting in the 1990s, computer networks began to start delivering services to private individual at homes thus enabling people to access remote information. Today access to remote information is coming in many forms. One area in which it is already happening is the access to financial institutions. Many people pay their bills, manage their bank accounts, and handle their accounts electronically. Today our own MTNL has also launched the facility of payment of the bills over the internet thus saving the people from the pain of standing in the long queues. Today with the advent of e-commerce, which is business over the network, home shopping is also becoming popular. This provides the facility to inspect the on-line catalogs of thousands of companies.

 

Another application called the World Wide Web provides easy access to the information systems like the arts, business, cooking, government health, history, hobbies, recreation, science, sports, travel, and other such million of topics.

 

• Person-To-Person Communication

 

Until now, we have now talked of applications that involve interactions between a person and a remote database. The second broad category of network use is person-to-person interactions and this has been made possible with our own Electronic mail or  E-mail, as it is popularly known. Today the E-mail is widely used by millions of people. In the near future E-mail is going to provide the facility o exchanging audio and video material over the net besides the textual part. Real-time E-mail allows remote users to communicate with no delay, possibly seeing and hearing each other as well. This technology makes it possible to have virtual meetings called videoconferences among far-flung people. Virtual meetings could be used for remote school, getting medical opinions from distant specialists, and numerous other applications. Worldwide newsgroups, which involve discussions on every conceivable topic, are already finding a commonplace among a select group of people, and this will grow to include the whole o the world population at large, In these discussion, one person posts a message and all the other subscribers of that particular newsgroup, can read it.

 

• Interactive Entertainment

 

            The third category is entertainment, which is a huge and growing industry. The most sought after application here is video-on-demand, In the future, it may be possible to select any movie or television program ever made, in any country, and have it displayed.

On your screen instantly. New films may become interactive, where the user is occasionally prompted for the story direction with alternate scenarios for all cases. Live television may also become interactive, with the audience participating in quiz shows, choosing among contestants, and on one team trying to shoot down the players on the opposite team, and so on.

In short, the ability to merge information, communication, and entertainment will surely give rise to a massive industry based on computer networking.

 

USES OF COMPUTER NETWORKS

 

There are numerous uses of computer networks, all of them are as follows:

 

• PRIVATE NETWORK

 

Many organizations have a substantial number of computers in operations, often located far apart. For example, a company with many factories may have compute at each location to keep track of inventories, monitor productivity, and do the local pay roll. The issue hears is resource sharing and the goal is to make all program, equipment, and especially data available to any one on the network without regard to the physical location of the resource and the user Network provides high reliability by having alternative sources of supply. For example, all files could be replicated on two or three machines; if one of them is unavailable the copies could be used.

 

Networks are helpful in saving money. Small computer have a much better price/performance ratio than large ones. Mainframes are roughly a factor 10 faster then personnel computer but they cost a thousand times more. In this model, the users are called clients and the whole arrangement is called client server model.

 

• COMMUNICATION

 

Communication using computer has brought a revolution in the world of Information Technology, particularly in the field of personal computer. We have always heard of networking or the term network. A network is a way or means of transmitting or receiving (exchange) information from one or more sources.

 

In computing networks, the origin of the information request utilizes the services of a network to locate and return the information. This is done with addresses. In the two previous examples of the car salesman and the employment agent, a telephone number can be considered the address of their associate or client. Addresses in computer networking are used in the same manner. These addresses identify the network resource. There are two popular architectures for networking-hierarchical and peer.

 

Peer networking does not need pre-defined network addressing. Instead, each resource on the network is seen as a peer. Each network resource is peer to the other network resources. When a new network resource joins the network it introduces it and notifies its peer of any other network resources that it knows about-peer networks are open and share network information.

 

• NETWORK HARDWARE

 

It is now time to turn our attention from the application and social aspect of the networking to the technical issues involved in network design. There is generally accepted taxonomy into which all computer networks fit, the tow dimension stands out as important: transmission technology and scale.

 

The network hardware components used are

(a) Transmission channel

(b) Network Interface Card (NIC)

(c) Servers

(d) Workstations

 

(a)        Transmission Channel

 

Generally following four types of channels are used for data communication in a LAN.

 

– Open Wire

– Twisted Pair

– Coaxial Cable

– Optical Fiber

 

(b)               Network Interface Card (NIC)

           

            Network interface units connect each device in the LAN network to shared transmission device. It contains the rules or logic to access the LAN. NIC is also used to implement LAN protocols and for device attachments. Its function depends on the type of topology used in LAN. In microcomputers, NIC may be installed as an add-on card.

 

(c)                Servers

 

            One of the major benefits of implementation of LAN is sharing expensive resources such as storage devices, printer etc. This is achieved through providing servers on the LAN. It is a dedicated computer, which controls one or more resources. This contains both hardware and software interface for LAN. Three major categories of servers used in LANs are:

 

(i) File Server

(ii) Printer Server

(iii) Modem Server

 

• NETWORK SOFTWARE

 

Operating System is required to operate on the LAN system, manage the tremendous workload with a number of various types of server attached to it. It has basically two-aspect (i) Server software (ii) workstation software. As in case of other multi-user operating systems, LAN operating system also facilitates the sharing of expensive resources such as printer, storage space etc. among all LAN users provides security for data and permits connection to other networks. There are various types of LAN operating system for example Novel Netware, WINDOWS NT, etc.

 

The first computer networks were designed with the hardware as the main concern and the software as an afterthought. This strategy no longer works. Network software is now highly structured. Most networks are organized as a series of layers or levels, each one built upon the one below it the number of layers, the name of each layer, the contents of each layer, and the function of each layer differ from network to network. How ever, in all networks, the purpose of each layer is to offer services to the higher layers, shielding those layers from the details of how the offered service are actually implemented. Layer N on one-machine carries on a conversation with layer on another machine. The rule and conventions used in this conversation are collective known as the layer N protocol. A protocol is an agreement between the communicating parties on how communication is to proceed.