Notes, Exercises, Videos, Tests and Things to Remember on Computer Network and Communication
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Ever since the beginning of time, people have had an uncontrollable need to communicate. Our nature drives us to exchange ideas, information and opinions. Without communication, we can’t learn, without learning, we can’t grow.and without growth, we shrivel up and disappear.
Creativity and communication drive the human race more than any other force. They arethe essential elements of life.
Networking is the ultimate level of communication. It transcends words and pictures to provide the pathway for thoughts, ideas and dreams. Networking that exists today is the result of millions of years of evolution and growth.
If we go through the history of communication, Charles Babbage and Countess of Lovelace are listed as the pioneer in the field of the present communicating world. Suddenly, the alphabet shrunk from twenty-six characters to two i.e. 0 and 1.
The world was thrust into a technological era that would spawn numerous networking inventions including the telephone, phonograph, motion pictures and the television. Finally, data communications were born a century later when computers were linked across distances.
NASA uses data communications to control the space shuttle and realign geosynchronous satellites, surgeons perform computerized operations from miles away, and because of data communications, today’s workforce is better to balance home and work by working from home or telecommuting. Data communications have had a profound effect on humanity.
The world will go on changing. It will become a small global village. In the new information age, humans will become very big fish in a very small pond.
A more comprehensive definition of the network: “A collection of distributed, intelligent machines that share data and information through interconnected lines of communication is called network”.
Fig: Computer Network
When two or more computers are brought together in connection with cable or without cable, that may extend within a limited room or to the entire world, then the computers are said to be in network connection. They merely perform the task of data sharing, transmission of data and communication.
Network elements fall into a place to create a compact LAN. Network communications provide the electronic pathway that computers use to communicate with each other. These elements include physical cabling, data signals and LAN standards.
Networking represents the rules of the road, defining protocols that instruct different machines how to speak (Internetwork Packet Exchange/Sequence Packet Exchange) for NetWare, TCP/IP (Transmission Control Protocol/Internet Protocol) for the Internet and AppleTalk for Macintosh computers.
Finally, network services simply define the things networks can do. Service requesters (clients) ask for resources and service providers (servers) grant them in the case of Client Server architecture. Common network services include file services, print services and messaging. A service provider is any combination of hardware and software that fulfills a particular job or function.
Network elements define the pathway and protocols for electronic communications. We are more concerned with what the message look like and how it travels from point A to point B in the imaginary computers in the network.
Here are three basic elements of networks:
Network services are the things that a network can do. These are the services provided by the computer. The major services that a network can provide are:
1. File Service:File Services includes file transfer and storage, data migration, file update synchronization and archiving. These features are the most popular reasons for networking.
2. Print Service:
Print Services produce shared access to valuable printing devices. A printer that is used as sharing in the network acts as the print server.
3. Message Service:
Message Services facilitate e-mail, manage integrated email and voicemail and co-ordinate object-oriented applications. Messaging is an exciting new player at the network party.
4. Application Service:
Application Services allows you to centralize high-profile applications. The server holds the applications (generally network versions) and they are accessed by the users in the network.
5. Database Service:
Database Services involve the coordination of distributed data and replication. The main server holds the data and determines the number of users that can access the database and modify the data. It also provides the print facility of the data in the network.
The term protocol refers to the set of rules and procedures that govern the transmission of messages over a physical networking medium. Topology describes the geographic orientation and arrangement of networking components.
Together, protocol and topology combine to create a networking standard. These standards are developed and controlled by the Institute of Electrical and Electronics Engineers (IEEE). The four major industry standards are:
Topologies define the geographic arrangement of server and workstations. File servers and workstations are arranged according to a variety of factors: speed, cost, reliability, distance and load requirements. Each topology is ideally used for different combinations of these factors:
Ethernet Standard for Bus Topology
The Ethernet topology was developed at the University of Hawaii, to connect computers on the various islands. It was a radio-based design. The term Ethernet is a compound word of either meaning air and net meaning network. Later, Robert Metcalfe went to Xerox’s Palo Alto Research Center (PARC) laboratories.
The radio portion was eliminated and changed to co-axial cabling. This was the string from station to station. This station to station topology was named linear bus.
Token-Passing Standard or Protocol
The token-passing protocol relies on a control signal called the token. A token is a 24-bit packet that circulates throughout the network, from NIC to NIC, in an orderly fashion. If a workstation wants to transmit a message, first, it must seize the token. At that point, the workstation has complete control over the communications channel.
The existence of only one token eliminates the possibility of signal collisions. This means that the only station can speak at a time on a multi-station ring.
ARC Net Standard or Protocol
The Attached Resource Computer Network (ARC Net Standard was created in 1977, at the Datapoint Corporation by a scientist named John Murphy. This standard predates the token-passing design adopted by IBM but uses very much the same technology ARC Net does not offer the same overall connectivity as Ethernet, but its hardware components are standardized sufficiently so that any ARC Net device from any manufacturer can be used on any other ARC Net LAN.
Khanal, R.C. Khanal, R.C. Computer Concept for XII. Pashupatigriha Marga, Thapathali, Kathmandu, Nepal: Ekta Books Distributors Pvt. Ltd., 2010. 67-72.
Adhikari, Deepak Kumar.,et.al., Computer Science XII,Asia Publication Pvt.Ltd
Some other major network services that a network can provide are: