ERIC Identifier: ED389277 Publication Date: 1995-11-00
Author: Lederman, Tim Source: ERIC Clearinghouse on
Information and Technology Syracuse NY.
Local Area Networks for K-12 Schools. ERIC Digest.
A Local Area Network (LAN) allows computing equipment to share information
from any device on a network with other devices on the same network, and
includes cabling, network transmission devices, network interfaces, and
computing devices. Some examples of computing devices on a LAN include:
File Servers--Computers which "serve" as central storage facilities for data
and program files.
Print Servers--Computers with one or more printers attached that provide
printing "services" to other computers on the LAN. Some printers have special
interfaces which allow the printer itself to act as a print server on a network.
Modem/Fax/Communications Servers--Devices which allow computers on the LAN to
communicate outside the network through a standard local telephone system. It is
also possible, with appropriate communications servers and software, to allow
external computers to "dial-in" to a LAN and communicate (data and/or faxes)
with devices on the LAN.
Different kinds of computers use
different methods, or protocols, to communicate with each other. Macintosh
computers use the AppleTalk protocol. Macintosh as well as PCs can use TCP/IP to
share information on the Internet. Some PCs require a Network Operating System
(NOS) to communicate. For example, Novell Netware is a popular NOS with PC
SERVERS AND CLIENTS
A server computer provides a special
service (examples described above) while a client computer requests and receives
a service from a server. The same computer could be a client or a server,
depending upon the type of data communications taking place. For example, a
computer could serve one of its files to another computer, but it could also
receive a file from that computer.
USES FOR LANS IN A SCHOOL BUILDING
school bulletin boards
centralized file sharing
access to library databases
access to the library card catalog
sending and receiving faxes
cost-effective connection to external networks
school information system for administrators, teachers,
students, parents and the community
USES FOR LANS DISTRICT WIDE
District uses for LANs include
all of the above, but in particular:
file sharing (student information)
transmission of records (attendance, grades, discipline)
shared use of one district connection to the Internet
Note: The interconnection of multiple building LANs is often accomplished by
Wide Area Networking (WAN) through radio transmission or through leased data
lines from a telephone company.
TYPES OF LANS
Common types of LAN hardware are Ethernet and
Token Ring. Ethernet predominates because it is easily designed and is composed
of data transfer devices which are less expensive than similar Token Ring
devices. The performance of Ethernet and Token Ring are roughly the same in most
situations. While it is possible to interconnect Ethernet and Token Ring
networks in the same location, it adds to cost and complexity. It is best to
keep the configuration of a school's data communication infrastructure as simple
as possible. Another standard for data communication is ATM (Asynchronous
Transfer Mode). It is more expensive than Ethernet or Token Ring but allows
higher speeds and will eventually allow better integration of computer-data,
digitized voice (telephone), and video. Some suggestions for choosing a LAN
If a school does not have an existing high speed data network, choose
If a school has an extensive Ethernet or Token Ring LAN, continue with that
If a school has a small Token Ring LAN and a significant extension of the LAN
is being proposed, two cost projections should be made. One estimate should
include costs for extending the existing Token Ring LAN, and another for
replacing the entire LAN with Ethernet.
If a school or district receives maintenance assistance from an organization
which only supports Token Ring, it is sometimes appropriate, if not necessary,
to choose Token Ring.
Cabling medium. The most
cost-effective cabling is Category 5 twisted-pair cable. This cable works with
standard Ethernet (10 Million bits per second, 10 Mbps) and "fast" Ethernet (100
Mbps), and is capable of speeds up to 150 Mbps with existing technology. This
has become the cable of choice in most LAN designs. Fiber-optic cable transmits
more data, but materials and installation are much more expensive. Proper
installation of fiber-optic cable is difficult in an old building because the
cable should not be bent during installation or when finally terminated (an 8" minimum bending radius is allowed).
Wiring plan. The location of wiring cabinets/closets is dependent on suitable
locations in the building and distances between computers. The maximum distance
between a computer and a network wiring cabinet/closet is 10 meters. A
refrigerator-sized cabinet where cables come together and network transmission
equipment (and sometimes servers) are stored can be enclosed with doors and
stand in a large room, or it can be placed as an open rack in a small room or
closet. Wiring cabinets/closets can be interconnected with twisted-pair cable,
but fiber-optic cable is a better choice for a variety of reasons, especially
Number of network connections (plug-in points) per room. Every computer needs
a network connection and each connection is comprised of (1) a plug-in point in
the wall of the room, and (2) wiring from this point to the wiring
cabinet/closet. Short and long term technology goals need to be considered when
planning the number of network connections per room.
Regular classrooms: Provide from one to six network connections per regular
Special classrooms: A minimum of one network connection should be provided in
home economics, physical education, music, and art rooms. Some schools equip
these rooms, and special education and reading rooms, just like regular
classrooms and provide up to six network connections.
Technology classrooms: This room could be equipped like a regular classroom, but
some districts place emphasis on computer and communication technology in their
technology curricula, especially at the middle school level, and may often
provide a network connection ratio of one connection per two students (15
connections in a room which holds up to 30 students).
Computing classrooms: It is advantageous to maintain at least one classroom per
school which provides one computer per student (30 network connections for
classes of up to 30 students).
Library: The library can become an even more versatile center for access to
information, research, and creative endeavors if it is wired with network
connections. Networked computers can be used to access an online card catalog
within the school, or online catalogs from other schools in the district. If the
school has a connection to external networks, a LAN allows every computer in the
library (and in the school) to access online catalogs and databases from a
variety of locations. A connection to the Internet, for example, provides access
to college, university, and government libraries throughout the world. Networked
multimedia workstations in libraries, allow students to access multimedia
databases, encyclopedias, and other graphic/visual-oriented resources. Many
school libraries locate network connections in as many places as possible in the
library. Librarians recognize that computers will become increasingly prevalent
in libraries as cost-effective replacements for expensive and space-consuming
resources like serials, periodicals, newspapers, an reference books.
Administrative offices: At least one network connection per person should be
provided for administrative purposes. Two connections per person will allow for
the connection of printers and other network devices.
Other offices: The offices of school nurses, psychologists, career/guidance
counselors, home/school counselors, and other academic support personnel should
have at least one network connection per person.
ADDITIONAL THINGS TO REMEMBER WHEN DESIGNING A SCHOOL'S
Network outlets. Locate near the area where the computers are/will be
Electrical outlets. Locate near the network outlets. If electrical outlets
are installed for future use, be sure the building's power supply and power
distribution infrastructure is adequate to handle the added computers. Because
the cost of providing electrical service can be substantial (as much as half of
the cost of a LAN itself), it is prudent to consider this cost at the same time
as estimating the cost of the LAN.
Furniture and fixtures location. When developing a wiring plan, consider the
placement of furniture and stationary fixtures.
Wiring. When wiring for a LAN, run additional cabling for other purposes at
the same time because the cost benefits are often substantial. The installation
of cabling for the following purposes should be considered when installing LAN
telephone and intercom
Potential use of space. Include every room in the LAN design which might ever
house a class, group, or office. It is much less expensive to design and install
a network for an entire building than it is to "modularize" into smaller LAN
projects (classrooms in one project and offices in another project). Room use
may change over the years (large closets may become offices or small classrooms,
There are many aspects of LAN design to consider
when developing a technology plan for a school building or school district. This
digest has indicated several key design issues, however one should contact an
experienced consultant or network designer before finalizing a LAN design.
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