Page 132 - DCAP516_COMPUTER_SECURITY

Computer Security

Notes The primary purpose of a computer network is to share resources. The main goal of
networking is Resource sharing. A second goal is to provide high reliability by having
alternative sources of supply. Another goal is saving money. 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. Computer
networks provide a powerful communication medium.
There are two important dimensions for classifying networks — transmission technology
and scale.

Transmission technology can be classified into two types:
Broadcast networks.
Point-to-point networks.

Broadcast networks: These networks have a single communication channel shared by all
the machines on the network.
Point-to-point networks consist of many connections between individual pairs of machines.
Multiple routes and intermediate machines may exist between a pair of machines; so
routing algorithms play an important role here.

A collection of interconnected networks is called an internetwork or just Internet. The
Internet refers to a specific worldwide Internet that is widely used to connect universities,
government offices, companies and private individuals.

A network topology is the basic design of a computer network. It details how key network
components such as nodes and links are interconnected.

There are three primary types of network topologies which refer to the physical and
logical layout of the Network cabling. They are star, ring and bus topology.

10.9 Keywords

Archive: A computer site advertises and stores a large amount of public domain, shareware
software and documentation.
Broadcast Networks: They have a single communication channel, which is shared by all the
computers on the network and therefore, any message transmitted by a computer on the network
is received by all the computers connected to the channel.
Error Control: The receiving end after completion of receiving the information must also be
capable of dealing with and recognizing the corruption.
Local Area Network: A LAN is a form of local (limited distance), shared packet network for
computer communications.
Metropolitan Area Network: In MAN, different LANs are connected through a local telephone
exchange using one or two cables but not switching elements.

Service Primitives: The primitives enable the service provider to perform some action or report
on an action taken by a peer entity.
Wide Area Network: A WAN may be defined as a data communications network that covers a
relatively broad geographic area to connect LANs together between different cities with the
help of transmission facilities provided by common carriers, such as telephone companies.

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