Page 111 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Exposure to Computer Disciplines

Notes Data transmitted may be digital messages originating from a data source, for example a computer
or a keyboard. It may also be an analog signal such as a phone call or a video signal, digitized into a
bit-stream for example using pulse-code modulation (PCM) or more advanced source coding
(analog-to-digital conversion and data compression) schemes. This source coding and decoding
is carried out by code equipment.

Computer networking or Data communications (Datacom) is the engineering discipline
concerned with the communication between computer systems or devices. A computer network
is any set of computers or devices connected to each other with the ability to exchange data.
Computer networking is sometimes considered a sub-discipline of telecommunications, computer
science, information technology and/or computer engineering since it relies heavily upon the
theoretical and practical application of these scientific and engineering disciplines. The three
types of networks are: the Internet, the intranet, and the extranet. Examples of different network
methods are:
 Local area network (LAN), which is usually a small network constrained to a small
geographic area. An example of a LAN would be a computer network within a building.
 Metropolitan area network (MAN), which is used for medium size area. examples for a city
or a state.
 Wide area network (WAN) that is usually a larger network that covers a large geographic
area.
 Wireless LANs and WANs (WLAN & WWAN) are the wireless equivalent of the LAN and
WAN.
All networks are interconnected to allow communication with a variety of different kinds of media,
including twisted-pair copper wire cable, coaxial cable, optical fiber, power lines and various
wireless technologies. The devices can be separated by a few meters (e.g. via Bluetooth) or nearly
unlimited distances (e.g. via the interconnections of the Internet). Networking, routers, routing
protocols, and networking over the public Internet have their specifications defined in documents
called RFCs.
6.1.1 Views of Networks

Users and network administrators typically have different views of their networks. Users
can share printers and some servers from a workgroup, which usually means they are in
the same geographic location and are on the same LAN, whereas a Network Administrator
is responsible to keep that network up and running. A community of interest has less
of a connection of being in a local area, and should be thought of as a set of arbitrarily
located users who share a set of servers, and possibly also communicate via peer-to-peer
technologies.

Network administrators can see networks from both physical and logical perspectives.
The physical perspective involves geographic locations, physical cabling, and the network
elements (e.g., routers, bridges and application layer gateways that interconnect the physical
media. Logical networks, called, in the TCP/IP architecture, subnets, map onto one or
more physical media. For example, a common practice in a campus of buildings is to make
a set of LAN cables in each building appear to be a common subnet, using virtual LAN
(VLAN) technology.
Both users and administrators will be aware, to varying extents, of the trust and scope characteristics
of a network. Again using TCP/IP architectural terminology, an intranet is a community of interest

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