What is a Network?
A network consists of two or more computers that are linked in order to share resources
(such as printers and CD-ROMs), exchange files, or allow electronic communications. The
computers on a network may be linked through cables, telephone lines, radio waves,
satellites, or infrared light beams.
The three basic types of networks include:
Local Area Network
A Local Area Network (LAN) is a network that is confined to a relatively small area. It
is generally limited to a geographic area such as a writing lab, school, or building.
Rarely are LAN computers more than a mile apart.
In a typical LAN configuration, one computer is designated as the file server. It
stores all of the software that controls the network, as well as the software that can be
shared by the computers attached to the network. Computers connected to the file server
are called workstations. The workstations can be less powerful than the file server, and
they may have additional software on their hard drives. On most LANs, cables are used to
connect the network interface cards in each computer. See the Topology,
Cabling, and Hardware sections of
this tutorial for more information on the configuration of a LAN.
A Metropolitan Area Network (MAN) covers larger geographic areas, such as cities or
school districts. By interconnecting smaller networks within a large geographic area,
information is easily disseminated throughout the network. Local libraries and government
agencies often use a MAN to connect to citizens and private industries.
One example of a MAN is the MIND Network located in Pasco County, Florida. It connects all
of Pasco's media centers to a centralized mainframe at the district office by using
dedicated phone lines, coaxial cabling, and wireless communications providers.
Wide Area Network
Wide Area Networks (WANs) connect larger geographic areas, such as Florida, the United
States, or the world. Dedicated transoceanic cabling or satellite uplinks may be used to
connect this type of network.
Using a WAN, schools in Florida can communicate with places like Tokyo in a matter of
minutes, without paying enormous phone bills. A WAN is complicated. It uses multiplexers to connect local and metropolitan
networks to global communications networks like the Internet. To users, however, a WAN
will not appear to be much different than a LAN or a MAN.
Advantages of Installing a School Network
- Speed. Networks provide a very rapid method for sharing and transferring files.
Without a network, files are shared by copying them to floppy disks, then carrying or
sending the disks from one computer to another. This method of transferring files
(referred to as sneaker-net) is very
- Cost. Networkable versions of many popular software programs are available at
considerable savings when compared to buying individually licensed copies. Besides
monetary savings, sharing a program on a network allows for easier upgrading of the
program. The changes have to be done only once, on the file server, instead of on all the
- Security. Files and programs on a network can be designated as "copy
inhibit," so that you do not have to worry about illegal copying of programs. Also,
passwords can be established for specific directories to restrict access to authorized
- Centralized Software Management. One of the greatest benefits of installing a
network at a school is the fact that all of the software can be loaded on one computer
(the file server). This eliminates that need to spend time and energy installing updates
and tracking files on independent computers throughout the building.
- Resource Sharing. Sharing resources is another area in which a network exceeds
stand-alone computers. Most schools cannot afford enough laser printers, fax machines,
modems, scanners, and CD-ROM players for each computer. However, if these or similar
peripherals are added to a network, they can be shared by many users.
- Electronic Mail. The presence of a network provides the hardware necessary to
install an e-mail system. E-mail aids in personal and
professional communication for all school personnel, and it facilitates the dissemination
of general information to the entire school staff. Electronic mail on a LAN can enable
students to communicate with teachers and peers at their own school. If the LAN is
connected to the Internet, students can communicate with others throughout the world.
- Flexible Access. School networks allow students to access their files from
computers throughout the school. Students can begin an assignment in their classroom, save
part of it on a public access area of the network, then go to the media center after
school to finish their work. Students can also work cooperatively through the network.
- Workgroup Computing. Workgroup software
(such as Lotus Notes) allows many users to work on a document or project concurrently. For
example, educators located at various schools within a county could simultaneously
contribute their ideas about new curriculum standards to the same document and
Disadvantages of Installing a School Network
- Expensive to Install. Although a network will generally save money over time, the
initial costs of installation can be prohibitive. Cables, network cards, and software are
expensive, and the installation may require the services of a technician.
- Requires Administrative Time. Proper maintenance of a network requires
considerable time and expertise. Many schools have installed a network, only to find that
they did not budget for the necessary administrative support.
- File Server May Fail. Although a file server is no more susceptible to failure
than any other computer, when the files server "goes down," the entire network
may come to a halt. When this happens, the entire school may lose access to necessary
programs and files.
- Cables May Break. The Topology section of this
tutorial presents information about the various configurations of cables. Some of the
configurations are designed to minimize the inconvenience of a broken cable; with other
configurations, one broken cable can stop the entire network.
[ Main | Overview | Protocol | Hardware | Cabling | Topology | Software ]
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