Page 12 - DCAP207_NETWORKS_DCAP406_COMPUTER_NETWORKS
P. 12

Unit 1: Introduction to Computer Networks




          You can create files and store them in one computer, then access those files from the other  Notes
          computer(s) connected to it.

          1.4 Networking Goals


          (a)  The main goal of networking is Resource sharing, and it is to make all the programs, data
               and equipment available to anyone on the network without the regard to the physical
               location of the resource and the user.

          (b)  A second goal is to provide high reliability by having alternative sources of supply. For
               example, all files could be replicated on two or three machines, so if one of them is
               unavailable, the other copies could be available.
          (c)  Another goal is saving money. Small computers have a much better price/performance
               ratio than larger ones. Mainframes are roughly a factor of ten times faster than the fastest
               single chip microprocessors, but they cost thousand times more. This imbalance has caused
               many system designers to build systems consisting of powerful personal computers, one
               per user, with data kept on one or more shared file server machines. This goal leads to
               networks with many computers located in the same building. Such a network is called a
               LAN (local area network).
          (d)  Another closely related goal is to increase the systems performance as the work load
               increases by just adding more processors. With central mainframes, when the system is
               full, it must be replaced by a larger one, usually at great expense and with even greater
               disruption to the users.
          (e)  Computer networks provide a powerful communication medium. A file that has been
               updated/modified on a network can be seen by the other users on the network
               immediately.

          Self Assessment

          Fill in the blanks:
          1.   The main goal of networking is …………………….

          2.   In a distributed system, the existence of multiple autonomous computers
               is……………………… to the user.
          3.   The computers on a ………………………. may be linked through cables, telephone lines,
               radio waves, satellites or infrared light beams.
          4.   You can create files and store them in one computer, then ………………… those files from
               the other computer(s) connected to it.
          5.   A ………………….. system is a special case of a network, one whose software gives it a
               high degree of cohesiveness and transparency.

          1.5 Network Hardware


          There are two important dimensions for classifying networks — transmission technology and
          scale.
          Transmission technology can be classified into two types:

          1.   Broadcast networks.
          2.   Point-to-point networks.



                                           LOVELY PROFESSIONAL UNIVERSITY                                    5
   7   8   9   10   11   12   13   14   15   16   17