What is Computer Networking? Goal, Component, Advantages of Networking?

    Define the term Computer Network. What is the goal of computer networking?

Computer Network:

i)                     A collection of autonomous computers interconnected by a single technology.

ii)                  Interconnected means they are able to exchange information.

iii)                Copper wire, fiber optics, microwaves, inferred and communication satellite can be used for connection.

GOALS OF NETWORKING

Ø  Resource and load sharing

ü  Programs do not need to run on a single machine

Ø  Reduced cost

ü  Several machines can share printers, tape drives, etc.

Ø  High reliability

ü  If a machine goes down, another can take over

Ø  Mail and communication

   Identify the five components of a data communications system.

 1.      Message. The message is the information (data) to be

communicated.  Popular forms of information include text, numbers, pictures, audio, and video.

2.      Sender: The sender is the device that sends the data message.  It can be a computer, workstation, telephone handset, video camera, and so on.

3.      Receiver. The receiver is the device that receives the message. It can be a computer, workstation, telephone handset, television, and so on.

4.      Transmission medium. The transmission mediums the physical path by which a message travels from sender to receiver.  Some examples of transmission media include twisted-pair wire, coaxial cable, fiber-optic cable, and radio waves.

5.      Protocol.  A protocol is a set of rules that govern data communications.  It represents an agreement between the communicating devices.  Without a protocol, two devices may be connected but not communicating, just as a person speaking French cannot be understood by a person who speaks only Japanese.

3.      What are the advantages of distributed processing?

Lower costs: Long-distance communication costs are declining at a slower rate than the cost of computer power. Distributed processing can reduce the volume of data that must be transmitted over long-distances and thereby reduce long-distance costs.

Performance: very often a collection of processors can provide higher performance and better price/performance ratio than a centralized computer.

 
Distribution: many applications involve, by their nature, spatially separated machines (banking, commercial, automotive system).

Reliability: if some of the machines crash, the system can survive.
Incremental growth: as requirements on processing power grow, new machines can be added incrementally.

Sharing of data/resources: shared data is essential to many applications (banking, computer supported cooperative work, reservation systems); other resources can be also shared (e.g. expensive printers).

Communication: facilitates human-to-human communication.

     What is the main difference between a distributed system and a network?

Computer Networks:

}  A computer network is an interconnected collection of autonomous computers able to exchange information.

}  A computer network usually require users to explicitly login onto one machine, explicitly submit jobs remotely, explicitly move files/data around the network.

•      Distributed System

}  In distributed system a collection of independent computers appears to its user as a single coherent system where a layer of software on top of the operating system.

}  The existence of multiple autonomous computers in a computer network is transparent to the user.

}  The operating system automatically allocates jobs to processors, moves files among various computers without explicit user intervention.

}  Thus, the distinction between a network and a distributed system lies with software rather than hardware.