K-12 Internetworking Guidelines
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From: Joan Gargano <jcgargano@ucdavis.edu>
Subject: K-12 Internetworking Guidelines
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ISN Working Group Joan Gargano
Internet Draft University of California, Davis
June 26, 1994 David Wasley
University of California, Berkeley
K-12 Internetworking Guidelines
Status Of This Memo
This Internet Draft provides technical guidance to the K-12
educational community on school networking and connections to the
Internet. Distribution of this memo is unlimited.
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
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Internet Draft s are draft documents valid for a maximum of six
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any Internet Draft.
This Internet Draft expires December 31, 1994.
Gargano, Wasley [Page 1]
Internet Draft K-12 Internetworking Guidelines June 1994
I. Introduction
Many organizations concerned with K-12 educational issues and the
planning for the use of technology recognize the value of data
communications throughout the educational system. State sponsored
documents such as the California Department of Education's
"Strategic Plan for Information Technology" recommend the planning
of voice, video and data networks to support learning and
educational administration, but they do not provide specific
technical direction.
The institutions that built the Internet and connected early in its
development are early adopters of technology, with technical staff
dedicated to the planning for and implementation of leading edge
technology. The K-12 community traditionally has not had this level
of staffing available for telecommunications planning. This
document is intended to bridge that gap and provides a recommended
technical direction, an introduction to the role the Internet now
plays in K-12 education and technical guidelines for building a
campus data communications infrastructure that provides
internetworking services and connections to the Internet.
For a more general introduction to the Internet and its applications
and uses, the reader is referred to any of the references listed in
the following RFCs:
1392 "Internet Users' Glossary"
1432 "Recent Internet Books"
1462 "What is the Internet"
1463 "Introducing the Internet - A Short Bibliograpy of
Introductory Internetworking Readings for the Network
Novice"
II. Rationale for the Use of Internet Protocols
In 1993, the Bank Street College of Education conducted a survey of
550 educators who are actively involved in using telecommunications.[1]
The survey looked at a wide variety of ways telecommunications
technology is used in K-12 education. Their findings on Internet
usage are summarized below .
"Slightly less than half of these educators have access
to the Internet, which is supplied most frequently by a
university computer or educational service.
________________________________________________________________________
1 Honey, Margaret, Henriquez, Andres, "Telecommunications and K-12
Educators: Findings from a National Survey," Bank Street College
of Education, New York, NY, 1993.
Gargano, Wasley [Page 2]
Internet Draft K-12 Internetworking Guidelines June 1994
"Internet services are used almost twice as often for
professional activities as for student learning
activities."
"Sending e-mail is the most common use of the Internet,
followed by accessing news and bulletin boards and
gaining access to remote computers."
The following chart shows the percentage of respondents that use
each network application to support professional and student
activities.
Applications Professional Student
Activities Activities
Electronic mail 91 79
News or bulletin board 63 50
Remote access to other 48 32
computers
Database access 36 31
File transfer 34 19
The value of the Internet and its explosive growth are a direct
result of the computer communications technology used on the
network. The same network design principals and computer
communications protocols (TCP/IP) used on the Internet can be used
within a school district to build campuswide networks. This is
standard practice within higher education, and increasingly in K-12
schools as well. The benefits of the TCP/IP protocols are listed
below.
Ubiquity TCP/IP is available on most, if not all, of the
computing platforms likely to be important for
instructional or administrative purposes. TCP/IP
is available for the IBM compatible personal
computers (PCs) running DOS or Windows and all
versions of the Apple Macintosh. TCP/IP is
standard on all UNIX-based systems and
workstations and most mainframe computers.
Applications TCP/IP supports many applications including, but
not limited to, electronic mail, file transfer,
interactive remote host access, database access, file
sharing and access to networked information
resources. Programming and development expertise
is available from a wide variety of sources.
Gargano, Wasley [Page 3]
Internet Draft K-12 Internetworking Guidelines June 1994
Flexibility TCP/IP is flexible, and new data transport
requirements can be incorporated easily. It can
accommodate educational and administrative
applications equally well so that one set of network
cabling and one communications system may be
used in both the classroom and the office.
Simplicity TCP/IP is simple enough to run on low-end
computing platforms such as the Apple MacIntosh
and PCs while still providing efficient support for
large minicomputer and mainframe computing
platforms. TCP/IP benefits from over twenty years
of refinement that has resulted in a large and
technically sophisticated environment.
Capacity TCP/IP supports local area network and wide area
network services within the entire range of network
data rates available today, from dial-up modem
speeds to gigabit speed experimental networks.
Communications can occur reliably among machines
across this entire range of speeds.
Coexistence TCP/IP can coexist successfully with other
networking architectures. It is likely that offices
and classrooms that already have networks may be
using something other than TCP/IP. Networks of
Apple Macintosh computers will probably be using
Appletalk; networks of PCs may be using any of the
common network operating systems such as Novell
Netware or LANManager. Mainframe computers
may be using IBM's System Network Architecture
(SNA). None of these proprietary protocols provides
broad connectivity on a global scale. Recognizing
this, network technology vendors now provide many
means for building networks in which all of these
protocols can co-exist.
Multimedia TCP/IP networks can support voice, graphics and
video as part of teleconferencing and multimedia
applications.
Compatibility All of the major Universities, as well as
thousands of commercial and governmental
organizations use TCP/IP for their primary
communications services. Commercial networks
such as Compuserve and America Online are also
connected to the Internet. Many State Departments
of Education have sponsored statewide initiatives to
connect schools to the Internet and many K-12
school districts have connected based upon local
needs.
Gargano, Wasley [Page 4]
Internet Draft K-12 Internetworking Guidelines June 1994
NREN The High Performance Computing Act of 1991 and
the Information Infrastructure and Technology Act
of 1992 provide the foundation for building the
national telecommunications infrastructure in
support of education and research. The National
Research and Education Network (NREN) will be
based upon Internet technology.
The benefits of internetworking technology have been demonstrated
through twenty years of use by thousands of organizations. This
same experience also provides tested technical models for network
design that can be adapted to K-12 campuswide networking in schools
of all sizes and technical development.
III. A Technical Model for School Networks
The vision of a modern communications network serving all primary
and secondary schools has been articulated and discussed in many
forums. Many schools and a few school districts have implemented ad
hoc network systems in response to their own perception of the
importance of this resource. This section of the ISN RFC presents a
standard network implementation model to assist county offices of
education and school districts in their planning so that all such
implementations will be compatible with each other and with national
networking plans intended to enrich K-12 education.
The future goal of "an integrated voice, data, and video network
extending to every classroom" is exciting, but so far from what
exists today that the investment in time and dollars required to
realize such a goal will be greater than most districts can muster
in the near term. We suggest that a great deal can be done
immediately, with relatively few dollars, to provide modern
communications systems in and between all schools around the nation.
Our present goal is to define a highly functional, homogeneous, and
well supported network system that could interconnect all K-12
schools and district, county, and statewide offices and that will
enable teachers and administrators to begin to use new
communications tools and network-based information resources. It
takes considerable time to adapt curricula and other programs to
take full advantage of new technology. Through the use of standard
models for implementation of current network technologies, schools
can begin this process now.
Many states have already developed communications services for their
schools. A notable example is Texas which provides terminal access
to central information resources from every classroom over a
statewide network. Modem-accessible systems are available in many
states that serve to encourage teachers to become familiar with
network resources and capabilities. Although modem-access may be
Gargano, Wasley [Page 5]
Internet Draft K-12 Internetworking Guidelines June 1994
the only practical option today in some areas, it always will be
limited in functionality and/or capacity. In anticipation of
emerging and future bandwidth intensive information resource
applications and the functionality that they will require, we
believe it is essential to provide direct network access to the
National Research and Education Network (NREN) Internet[2] from
computers in every classroom.
The Internet communication protocols, commonly known as "TCP/IP,"
are the "glue" that will allow all computers to communicate. As
noted above, software that implements Internet protocols is
available for all modern computers. These protocols support a very
wide variety of applications, from electronic messaging to
client/server data access. The use of Internet protocols will
ensure that all networked computers will have direct access to the
vast range of existing information and education resources on the
Internet, as well as to the emerging National Information
Infrastructure.
Approach
The implementation we suggest would use current proven and cost
effective technology and would be expandable and upgradable to newer
technology with minimum additional investment. This approach
requires careful, modular design to meet the following criteria:
1) Any physical infrastructure development should be general and
flexible enough to be reused as technology improves. For
example, a school office might have a simple terminal today
which could be wired to a network adapter serving the school
building. Later a Macintosh, DOS, or Windows-based PC might
replace the terminal, and the type of connection to the network
would change accordingly. However, the wiring between the
office and the network "hub" site could remain the same if it
is designed properly to begin with. This is an important
consideration since wiring typically represents 20 to 40% of
the cost of individual network hookups;
2) Existing computers and terminals in schools and district
offices should be integrated as much as possible into the
communication system. This installed base represents a large
investment, albeit in many cases a somewhat dated set of
equipment. Wholesale replacement of that base would be a
large additional burden on funding resources.
________________________________________________________________________
[2] The Internet is a "network of networks" that interconnects institu-
tions of higher education, research labs, government agencies, and
a rapidly growing number of technology and information vendors.
Gargano, Wasley [Page 6]
Internet Draft K-12 Internetworking Guidelines June 1994
A consequence of the above is that the user interface and the
services available will vary depending on the type of equipment
used to access the network. For example, DOS PC s, Macintosh
computers, or Unix workstations would be connected directly to
Local Area Networks (LANs) and would be provided with communi-
cations software to support a broad set of functions, many of
which will have graphical user interfaces and will make use of
client/server technology. Apple-II computers, "dumb" terminals,
or other such devices could be connected to intelligent network
hubs that would allow access to network server computers or
information resources, but almost certainly will not support
the full range of functionality provided by a direct network
connection. In the short term, this is a limitation that we
must accept;
3) Network servers will be located where they can be managed and
supported, and also provide access paths with adequate
bandwidth. A system of hierarchical servers should be created
in larger school districts, with automatic transfer of common
information from a central system to the secondary systems each
night, or at appropriate intervals. Local servers will allow
each school to provide on-line information particular to its
programs and community. This model optimizes use of network
bandwidth as well;
4) School interconnect topologies (links) must be both cost
effective and manageable. Communication between schools,
district offices, county offices of education, and the State
Department of Education must be reliable and of sufficient
capacity to support the primary applications as well as allow
development of new applications.
Capacity is measured both by total data traffic volume and by
response time when information is requested over the network.
Reliability is measured by the percentage of time that the
network is able to transport data. Reliability should be well
over 99.7%. Capacity should be such that no more than 10% of
the communications bandwidth is used during a typical work day.
This is intended to leave adequate capacity for good response
time to short term communication demands.
Many schools already have some form of communications
infrastructure in place. In some cases this infrastructure can
be adapted to newer technologies; in other cases it may have to
be replaced over time. These issues are explored further
following presentation of the basic model that serves as a
guideline for future communications system development.
Implementation Model
There is no one "blueprint" for a network that will drop into every
school. Each school will have particular physical constraints,
functional needs, an existing technology base, funding constraints,
Gargano, Wasley [Page 7]
Internet Draft K-12 Internetworking Guidelines June 1994
and opportunities for collaboration with vendors and support groups
in its area. What is presented here is a set of general guidelines
that can be followed in the planning of a school network
implementation.
The strategic decision to use Internet protocols in developing
school networks provides the opportunity to avoid the major expense
of building new statewide backbone infrastructures in the near term.
Interconnection of schools, districts, county offices of education
and the State Department of Education can be accomplished by
acquiring Internet connection service from any of the existing
Internet service providers in the state[3] . It is critical that
Internet connection service meet criteria for reliability and
capacity but connection to any Internet service provider will
provide communication capability to all other Internet subscribers
within the state, the nation, and the world.
Internet technology is designed to allow very flexible intersite
topologies, but a hierarchical topology is the simplest to engineer.
Generally this will mean hierarchical connection of school
facilities to district offices, in many cases further aggregated at
county offices, and finally a link to an Internet service provider.
Coordination of circuit services and a single point of connection to
an Internet service provider serves both to minimize overall costs
and increase opportunities to make use of newer technologies.
The basic school network implementation model is quite simple:
create a local area network (LAN) within each school building or
cluster of buildings, provide at least one network server for that
LAN, interconnect that LAN with the local school district offices
where a similar LAN should be installed and where centrally managed
information resources should exist, and connect the district offices
to the nearest Internet service provider, possibly through the
county office of education.
Primary technical support for network monitoring and problem
resolution, and for managing network resource servers should come
from the district or county offices initially to avoid unnecessary
duplication at the local level. As expertise is developed at the
local level, more of the responsibility for daily operation and
problem resolution can be assumed by individual schools.
It is impossible to cover all conceivable scenarios for
implementation of this model in specific schools. However, it is
possible to state general principles that should be followed in
designing school network implementations. The discussion below is
organized into sections corresponding to the basic model summarized
in the previous paragraph. It includes a description of the general
principles that are important to each level of the implementation.
________________________________________________________________________
[3] "Connecting to the Internet", Susan Estrada, O Reilly & ssociates
Inc. (ISBN 1-56592-061-9) lists Internet serviceproviders in
California and the nation.
Gargano, Wasley [Page 8]
Internet Draft K-12 Internetworking Guidelines June 1994
Step 1: School Local Area Network Implementation
A "school" is used here to mean a building or cluster of buildings
that are managed as a unit and typically are on contiguous, district
owned property. Implementation of a LAN in this setting will
involve installation of a cabling system to distribute the network
throughout the structure(s), installation of premise wiring to
support connections of computers and terminals to the network
distribution system, installation of one or more network server
machines in a central location[4] , and provision of a network router
and telecommunications circuit or radio link to connect that school
to the district offices.
The most common LAN technologies in use today are ethernet and
LocalTalk[5] . Both are quite inexpensive and easy to install and
maintain. Ethernet is adaptable to most modern computers and is
built-in to high performance workstations such as Sun, Hewlett-
Packard, SGI, or Digital Equipment Corporation computers. LocalTalk
is built-in to all Macintosh computers and is adaptable to DOS PC
computers as well. Ethernet is roughly 20 to 40 times faster than
LocalTalk. Therefore ethernet is recommended for all computer
connections, when possible, and for the school LAN "backbone" or
network distribution system.
1.1 Network Adapters and Software
Individual computers will require network or communications adapters
and appropriate software. Table 1 gives basic recommendations for
the computers most commonly found in schools. Basic communications
software is available in the public domain for many personal
computers at no cost. More sophisticated software is being
developed by a number of vendors for applications such as electronic
mail, distance learning, and multimedia database access. For
example, the California Technology Project is developing very easy
to use software for Macintosh and DOS or Windows PC computers that
will enable access to a wide variety of information resources and
services. Schools should look at all the available software and
base choices on required functionality and support costs as well as
acquisition costs.
In locations where computers will be purchased, the choice of
computer type should be driven by the availability of software for
the particular application(s) to be supported. Almost all modern
computers can be attached to the type of network described in this
document.
________________________________________________________________________
[4] Other protocols, such as AppleTalk or Novell s IPX, may be supported
on aschool s local area network (LAN) as needed for local function
such as printer sharing or local resource servers.
[5] IEEE 802.5 Token Ring is not recommended for new installations. It
is more expensive and it is not available for as wide a range of
computers.
Gargano, Wasley [Page 9]
Internet Draft K-12 Internetworking Guidelines June 1994
Equipment Type Network Adapter Communication
Software
________________________________________________________________________
Simple terminal "Network Access Server" Built-in to the
located centrally. networkaccess server.
Apple II, Amiga, Serial asynchronous Serial communications
Tandy, Commodore, port that will allow software that emulates
older IBM PC s, et connection to the a simple terminal.
above.
Newer IBM PC Ethernet adapter car TCP/IP "TSR" software,
with "10-base-T" port. for example "FTP
"Thin-net" port may be Software" package.
used in lab clusters. Additional software for
special appl.
Older Apple PhoneNet adapter MacTCP or equivalent
Macintosh computers (external) and shared plus "telnet" and "ftp".
LocalTalk to ethernet For example, NCSA
router, for example the Telnet. Additional
Shiva FastPath. software for special
applications, eg.
"electronic mail
client."
Newer Apple May use same as the Same as the above.
Macintosh computers above. For higher
performance, use an
ethernet adapter card
with "10-base-T port.
"Thin-net" port may be
used in lab clusters.
Unix workstations Ethernet adapter card, Typically comes with
if not already built in. the basic system.
Additional software
may be needed
for special
applications.
________________________________________________________________________
Table 1: Network Adapters and Software for Typical Computers
1.2 Premise wiring
A major component of the implementation will be installation of
cabling to connect individual computers or clusters of computers to
the LAN. The recommended topology is a "star" where each computer
Gargano, Wasley [Page 10]
Internet Draft K-12 Internetworking Guidelines June 1994
is wired directly to a "hub site" within the building as shown in
Figures 1 & 2. A cluster of computers, typically found in a
teaching lab or library, may be interconnected within the room where
they are installed, and the cluster connected to the hub site with a
single cable as shown in Figures 3 & 4.
The recommended premise wiring is "unshielded twisted pair" (UTP)
wire that meets the Electronic Industries Association (EIA) category
5 standards for high speed data communication service[6] . While 2
pair cable may be adequate for most purposes, industry standards
recommend installation of 4 pair cable. The difference in cost is
minimal so we recommend installation of the latter. One end of each
cable terminates in a category 5 RJ-45 jack [7] located near the
computer. The other end terminates on a standard "110 distribution
block "[8] at the hub site utility closet. A labeling scheme must be
chosen and strictly adhered to so that cables can be identified at
both ends later, as needed.
[Figure 1: Individual ethernet connection to the network]
[Figure 2: LocalTalk connection to the network]
In most cases, the hub site utility closet will be shared with
telephone services. It is essential that a separate wall area be
set aside within the closet for data service interconnections.
Typically there will be a "field" of interconnect blocks for
termination of all premise wires, another field for termination of
trunk cables (used for low speed data terminals), and a third field
for hub equipment ports. Interconnections between premise wiring
blocks and hub or trunk blocks are installed as needed in order to
provide the appropriate service to each location where communication
service is required.
[Figure 3: A cluster of computers connected to the network]
[Figure 4: A Macintosh cluster connection to the network]
Installation of wiring in a building typically is performed by a
qualified data wiring contractor. This is a critical aspect of the
program and must be planned and installed professionally with both
________________________________________________________________________
[6] See EIA/TIA-568 "Commercial Building Telecommunications Wiring
Standard."
[7] A standard RJ45 jack can be used for ethernet or lower speeds if
initial cost is amajor factor. Such jacks can be replaced with
category 5 versions later as needed.
[8] In older sites, M66 distribution blocks may already be installed.
These can be used for the time being but will not support newer
higher speed technologies.
Gargano, Wasley [Page 11]
Internet Draft K-12 Internetworking Guidelines June 1994
current and future requirements in mind[9] . To be prepared for
future distribution of video signals, school network planners should
consider installation of RG-59 coaxial cable to those locations
where video may be required at the same time that the UTP premise
wiring is being installed. The coaxial cable would terminate on a
wall plate mounted "F" connector in the classroom, and would be left
unterminated in the utility closet. Future technologies may support
video signals over other media so the installation of RG-59 cable
should be limited to near term potential requirements.
It will be cost effective to install premise wiring to as many
locations as might ever serve a computer. This will include
administrative offices as well as classrooms, laboratories as well
as libraries. In high density locations such as offices,
consideration should be given to installation of two UTP cables to
each outlet location in order to provide the potential for several
computers or workstations. Terminating both cables on the same wall
plate will add little to the overall wiring project costs and will
add greatly to the flexibility of the system. Premise wiring that
is not to be used initially will not be connected to any electronics
in the hub site.
Hub sites should be utility closets or other protected, non-occupied
areas. Hub sites can be created by construction of small closets or
cabinets in low use areas. A hub site must be located within 300
feet of any connection. Typically, multiple hub sites are required
in large or multi-story buildings.
1.3 Network Distribution System
All hub sites within a school must be interconnected to complete the
school LAN. The design of this network distribution system will
depend greatly on the physical layout of the school buildings. We
assume that ethernet technology will be used since higher speed
technology is still quite expensive.
[Figure 5: A complete small school LAN]
If all hub sites are within 300 cable feet of a central location,
then 10-base-T wiring can be used from a central hub to connect each
hub site, as shown in Figure 5. If longer distances are required,
depend on the layout of the buildings to be served.
________________________________________________________________________
[9] See "Virtual Schoolhouse - A Report to the Legislature on
Distribution Infrastructures for Advanced Technologies in the
Construction of New Schools, K through 12" (Department of General
Services, State of California, Feb 1993) for example conduit and
utility closet plans.
Gargano, Wasley [Page 12]
Internet Draft K-12 Internetworking Guidelines June 1994
either thin-net or standard thick ethernet can be used. Fiber optic
cable can be used if distance requires it and funding permits[10].
Specific design of the "backbone" network distribution system will
With proper design as many as 250 computers can be connected to a
single ethernet segment. Most often the practical maximum number
will be much lower than this due to the amount of data sent onto the
network by each computer. For planning purposes, one can assume
100-125 computers per segment. Beyond that size the network must be
subdivided using "subnetworks." Design of a such a system is not
difficult, but is beyond the scope of this document.
The network distribution system cabling should include unshielded
multi-pair trunk cabling as well as ethernet trunk cabling. The
multi-pair trunk cable will be needed to connect terminals or older
computers emulating terminals to a central "network access server"
(NAS). A typical NAS can serve from 8 to 128 such connections. It
is most cost effective to provide one per LAN, if needed. The NAS
connects directly to the ethernet LAN.
1.4 Local Network Server
It is highly recommended that each school install a "network server"
to support local storage of commonly used information, software,
electronic mail, and other functions that may require high speed
communication to the user s computer. Since the connection to the
outside network will be much slower than the school LAN, it will be
most efficient to access information locally. In particular,
software that is to be shared among the school s computers must be
stored locally since it would be very tedious to transfer it across
the slower external link. The network server will be connected
directly to the ethernet network.
The location of the server should be chosen carefully to ensure its
protection from abuse and environmental damage. Traditionally the
school library is the focus of information gathering and storage
activities and many school libraries have clusters of computers or
terminals already installed. The library would be a very logical
place to locate the network server computer. The Network Router
(see below) might also be located there if a suitable utility space
is not available.
The network server will be a small but powerful computer with a
large amount of disk storage capacity, typically 1-4 gigabytes. It
will run software capable of supporting access by a large number of
users simultaneously. It could also support dial-in access from
________________________________________________________________________
[10] If fiber optic cable is installed, consideration should be given
to including both multimode fiber for current and future data
requirements and single mode fiber for video and future very high
speed data systems.
Gargano, Wasley [Page 13]
Internet Draft K-12 Internetworking Guidelines June 1994
teacher s or student s homes using standard inexpensive modems[11] .
If more than a few modems are to be installed, a NAS might prove
more cost effective. If dial-in access is to be provided to more
than a few school sites within a district, a single central modem
pool maintainted at the district offices will be the most cost
effective.
1.5 External Connection
A single communication circuit will connect the school LAN to the
local school district offices. In the school, there will be a
Network Router attached between the LAN and this circuit. On the
LAN side, the connection will be a typical ethernet cable. On the
external side, the connection will depend on the type of
communication circuit used, as discussed in step 2 below.
Step 2: Interconnection of Schools with District Offices
All schools within a district should be connected individually to
the network router at the school district offices. This "star
topology" will be much easier to manage and the capacity of each
school s connection can be increased appropriately as needs change.
Several standard communication circuit services may be used to
effect this connection. The least expensive for situations where
only limited use is needed will be dial-up using high speed modems.
However, this type of connection is not recommended for serious
usage due to its very limited capacity. Also, since most schools
receive telephone service under business tariffs, usage will be
measured and the cost will be dependent on how long the connection
is maintained. This will be true in general for other "switched
services" as well such as "switched-56" and ISDN. Dedicated
(permanently installed) communications circuits are strongly
recommended since they will allow unattended access to and from the
school network at all hours. This will be particularly important if
information files are to be down-loaded during the night to local
network servers or teachers and students are to access the school s
information resources from home.
Table 2 shows the most common options for dedicated circuit
services. Costs are indicated in relative terms since they vary
greatly by location and as tariffs are modified. The exact costs
must be determined by contacting local communications service
providers. Total cost must take into account the equipment needed
at each location as well.
________________________________________________________________________
[11] Access control with user authentication is essential if
dial-in service is to be provided.
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Type of Circuit Data Rate Relative cost
________________________________________________________________________
Voice grade leased 20 kilobits per sec modest[12]
telephone line (Kb/s)
ADN-56 56 Kb/s high
ISDN, where 64 or 128 Kb/s modest[13]
available
Low power radio 64 to 256 Kb/s high startup
cost
Frame Relay 56 Kb/s to 1.5 Mb/s modest to high
DS1 1.5 megabits per sec very high
________________________________________________________________________
Table 2: External Connection Communications Options
Frame Relay communication services are becoming available in many
areas. Frame Relay is a shared, packet based data transport
service. A school site would contract for Frame Relay service as
part of a larger service group that includes the school district
office and may include the Internet service provider. All members
of that group would share the communications capacity. The
advantage of this service is that only one end of the circuit needs
to be ordered (each member orders a connection to the common
service) and the capacity offered to each member can be upgraded
independently. Also, in many areas the cost of Frame Relay service
is not dependent on distance to the service provider which will make
service to rural schools much less expensive than equivalent
services. Overall system costs will be minimized since the central
router at the district office will need fewer connections.
If Frame Relay is chosen, the overall service group must be
carefully engineered. For example, since all schools would share
the connection to the district office (and possibly to the Internet
service provider), that must be a high capacity connection. For the
initial design, the aggregate capacity of all school links should
not exceed the capacity into the district office (or the Internet
service provider) by more than a factor of 3 or there may be
noticeable congestion and variability in response times across the
system. There are many other factors that must be considered as
well, such as the virtual connection topology and how best to
connect to an Internet service provider. Therefore, it is
________________________________________________________________________
[12] Measured service charges must be taken into account.
[13] At this time, most ISDN tarriffs include message unit charges
which can make theuse of ISDN prohibitively expensive for
full-time connectivity.
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recommended that an experienced network engineer be utilized to
develop an operational plan for Frame Relay if it is chosen as the
school interconnection service.
Future options for interconnecting schools and district offices will
include[14] :
o Community Access Television (CATV) cable systems offering
either shared or dedicated bi-directional data communication
services,
o metropolitan area fiber optic communications service
providers,
o Switched Multi-megabit Digital Service (SMDS) providing data
transport service at speeds up to 34 megabits per second.
o Asynchronous Transfer Mode (ATM) connection services
supporting voice, data, and video communications at speeds
into the gigabit per second range.
The costs for the last three options are unknown at this time, but
may be generally higher than those indicated in Table 2. The cost
for the CATV option may be negotiable as part of the local CATV
contract with the community.
As demands for network speed develop due to heavy use of multimedia
or other bandwidth intensive application, higher speed
communications circuits can replace the initial circuits with
minimal change in the equipment or LAN. This gives great
flexibility in tailoring service to funding levels and application
needs.
Step 3: School District Office LAN and Support Systems
The School District offices should form the focal point for
interconnection of all schools in the district. Within the District
offices, network operations can be monitored and problem resolution
managed. One or more network servers can provide essential network
support as well as central archiving of common information and
software.
A critical role of the district office will be to manage Internet
"Domain Name System " (DNS)[15] service for the district s schools.
DNS is required of all Internet networks. It defines the basic
________________________________________________________________________
[14] Many more options will become available as new technologies come
to market.
[15] See RFCs 1034 and 1035 for the full explanation of DNS.
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network level identity of each computer, workstation, server, and
active network component. This function is described more fully
below under Network Management and Operational Monitoring.
The district offices should be wired in a manner similar to a
typical school, as shown above. This will allow teachers,
superintendents, and principals to communicate and share information
easily. In addition, an NAS connected to a central pool of modems
could provide dial-in access to the district network.
Step 4: Interconnection of the School District with the Internet
Connection of the entire school district to the Internet will take
place through the district office interconnect site, as shown in
Figure 6. This hierarchical model can be extended another level to
interconnection of the school district offices through the county
office of education facilities. Many administrative information
resources could be located at the county level, and there might be
cost savings if the entire county connects to an Internet service
provider through a single point. The bandwidth required for this
single connection, however, will be much greater than that required
for each school district since traffic will be aggregated.
This hierarchical topology also provides a logical model for network
support and information resource management. The school district or
county offices can provide continuous monitoring of the network and
provide high level technical expertise for problem resolution,
relieving the individual schools of this burden. Interactions with
communications circuit providers and Internet service providers will
be more effective if handled through a central "trouble desk."
Similarly, it is highly desirable that network users have a single,
well known point of contact in case of problems or questions.
Internet service should be acquired from the most cost effective,
reliable Internet service provider. Circuit services can be similar
to those shown in Table 2 above. The higher speed services should
be considered if traffic demands increase and funding permits.
Circuit costs usually will be lowest when connecting to the provider
with the nearest "point of presence" (POP), but newer technologies
such as Frame Relay and SMDS[16] make circuit costs less dependent on
distance. The Internet connection will require a high quality
router that can be configured to interact correctly with the service
provider s routers. In most cases, this can be the same router
used to support the local school connections.
[Figure 6: Interconnection of schools to the Internet through local
School District Offices]
________________________________________________________________________
[16] At this time, SMDS services are not widely available.
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Integration of Existing School Networks
Many schools have developed LAN systems in support of particular
classroom activities or administrative functions. In some cases the
technologies used are not those recommended for new installations.
If these older LAN systems are capable of transporting Internet
protocols they may be integrated into a new LAN system and replaced
later as funding permits.
For example, IEEE 802.5 Token Ring is often used to interconnect DOS
PC-type computers and IBM minicomputer servers. Token Ring networks
can transport Internet protocols and software is available for DOS
computers to support basic Internet functions. Many Internet
routers support optional Token Ring adapters. This is the
recommended way that existing Token Ring LANs can be integrated into
a wider school LAN system in order to extend Internet information
resources to those PC users.
Another example is a Novell Network system using ethernet as a LAN.
The ethernet LAN, if implemented well, is perfectly capable of
transporting Internet protocols as well as Novell protocols,
simultaneously. Each PC or Macintosh can be given software that
will allow both Novell and Internet services to be used as needed.
This coexistence is important so that, for example, a person using a
PC that depends on the Novell server for disk file space can
transfer a large file from a remote Internet server to the PC s
pseudo-disk. It also permits each user to run client software such
as Eudora (electronic mail), Gopher (information services), and
Mosaic (World Wide Web information services) which require direct
Internet access. To integrate the Novell ethernet LAN into the
wider school LAN system a simple ethernet repeater can be used in a
manner similar to Figure 3 above.
An alternative to supporting both protocols that is sometimes
suggested in cases such as the one cited above in which a network
server already exists is to use the server as a "network application
gateway." This approach is strongly discouraged. It is essential
that each computer and workstation support Internet protocol data
communication directly so that modern client/server applications can
be supported where the server or servers may be located anywhere on
the Internet. The "gateway" approach severely restricts the
workstation s potential ability to access multimedia and other
important information resources.
Some technologies, such as "arcnet," may not be capable of
supporting Internet protocols but may offer "terminal emulation"
shared access to something like a "modem pool." The modem adapter
might be rewired to connect to ports on a network access server
instead. This would provide simple access to information resources
for the arcnet users.
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In any case, older LAN technologies should not be expanded and
should be phased out as funding permits. It is critical that there
be a relatively homogeneous installed base of technology in order
that new applications of information resources can be provided to
the entire school community.
Network Management and Operational Monitoring
All networks require some level of network management in order to
ensure reliable service. Monitoring of the health of the network
can help identify problems before they become detrimental to network
users. It also can help predict trends in traffic patterns and
volume.
Internet technology network management consists primarily of
determining the proper routing parameters for optimal and reliable
network operation, assignment of network Internet Protocol (IP)
addresses and maintenance of a network-accessible database of node
names corresponding to each address[17] , and monitoring the daily
operation of the network. These functions typically are performed
by the staff of a Network Operations Center (NOC).
Domain Name System
The Internet Domain Name System (DNS) is the mechanism for
documenting and distributing information about the name and address
of each computer attached to the network (network nodes). The DNS
service is provided by software that runs on the main network
server. It uses a database that is created and maintained by the
NOC staff.
An Internet address is the numerical identifier for a node and it
must be unique among all nodes associated with the network.
Furthermore, if the network is to be part of the global Internet,
all addresses must be legitimate within the worldwide Internet
system.
Associated with each numerical address can be one or more "node
names." Although computers have no difficulty using numerical
addresses, it is often easier for computer users to remember and use
the node names rather than the numerical addresses. In particular,
electronic mail addresses use node names. DNS node names are
hierarchical and by appropriately using this hierarchy "subdomains"
can be assigned to each school site or district office. In this
way, naming can be structured to be flexible as well as meaningful
in the context of the whole organization.
________________________________________________________________________
[17] See RFC 1480 for a discussion of Internet naming conventions
for school networks.
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A plan for the assignment of IP network addresses and node names
should be developed early in the planning for the network
installation. Initially, the database serving the DNS should reside
on the "district server" so that there is one site at which all
assignments are officially registered. As the network grows and
expertise is developed, secondary DNS service can be run on the
servers at larger school sites.
The main DNS server for the district should be located as close to
the Internet connection (topologically) as possible. This proximity
is to help ensure that network problems within the district network
will have minimal impact on access to the server. This design is
illustrated in Figure 1 where the district server is on an ethernet
connected directly to the main distribution router.
Associated with the assignment of node names and addresses should be
a database of specific information about the computers connected to
the network. When trying to resolve problems or answer user
questions, it is very important to know where the computers and
other nodes are located, what type of computer and software are in
use, and what type of network connection is installed. With proper
software this database can be used to extract the DNS database
discussed above.
Network Monitoring
Internet network monitoring serves three primary purposes:
1) Constant observation of the "health" of the network, network
components, and external network connectivity. Standard Simple
Network Management Protocol (SNMP) support is built-in to most
active components today. Even network servers and workstations
can be monitored in this way. Operations staff can be provided
with network monitoring stations that will display alerts
immediately upon detecting a wide variety of problems or
anomalies;
2) Collection of statistics on the performance of the network and
patterns of traffic in order to identify needed enhancements or
re-engineering. Using the same SNMP capabilities mentioned
above, data on packet forwarding and total traffic volume can
be collected and used to generate periodic reports on network
utilization;
3) More rapid problem resolution. When problems do occur, SNMP
tools can help to pinpoint the source of the problem(s). Such
problems include transient routing anomalies, DNS query
failures, or even attempts at breaking into network accessible
host computers.
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Since network management and monitoring is a technically
demanding task and requires special equipment and software, it
should be a centralized function in the initial design of school
network systems, as discussed above.
IV. Network Support
Summary
The model for school network implementation described above is based
on broad experience with this technology in higher education and
administrative environments. Many schools have already installed
networks very similar to this model. We believe that it is a
practical first step towards bringing a powerful resource to bear
for enriching all of the nation s school programs.
None of the suggestions above preclude or postpone in any way future
development of an integrated voice, data, and video network for the
nation s schools. Use of existing Internet carriers does not in any
way preclude future development of a separate "backbone" for the K-
12 community if such a "backbone" is determined to be cost effective
or required for enhanced functionality. Rather, the infrastructure
recommended above can be the foundation at the local level in
preparation for future high capacity networks.
The installation of a campuswide network or Internet connectivity
will also require a commitment to ongoing network support and its
related resource requirements. There are two major areas of network
support, network operations and user services. These support
functions are usually performed through the establishment of a
Network Operations Center (NOC) and Network Information Center
(NIC), however both functions can be performed by the same
individual or groups of individuals.
Network Operations Center (NOC)
The Network Operations Center (NOC) oversees the performance of the
physical network and some of its software support systems. The
staff may install networks, configure network devices and provide
configurations for computers attached to an organization-wide
network. Real-time monitoring of the network can be performed using
the Simple Network Management Protocol and many vendors produce
monitoring systems that graphically display network performance, log
events and usage, and produce trouble tickets. The use of this type
of network monitoring allows NOC staff to quickly detect problems
and greatly reduces the personnel required to perform this function.
Routine monitoring of the network can help to anticipate problems
before they develop and lead to reconfigurations and upgrades as
indicated. If problems do arise, NOC personnel may go on-site to
troubleshoot a problem and repair it. If the problem is not local,
NOC personnel will work with school district, County or regional
network technical staff to resolve the problem.
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NOC personnel also assign addresses to network computers and devices
and maintain the Domain Nameservice (DNS) for their organization.
Domain Nameservice is a machine registry service that runs on a
network server and enables access to machines by easy to remember
names, rather than a network number. DNS is required for any
organization connected to the Internet and critical to the
establishment of an electronic mail system.
It is most cost effective to have the Network Operation Center serve
an entire organization or region. In order to ensure timely service
all the way out to the most remote LAN, it is recommended that an
organization assign local area network administration duties to on-
site personnel to interact with NOC staff and assist with the
maintenance of the network. In the case of a school district,
administrative support staff, teachers, librarians or school based
technical staff can each take responsibility for a LAN or group of
LANs. If a problem arises, it can be reported to the LAN
administrator. The LAN administrator can determine if the problem
is local or remote and if NOC staff need to be notified. If so, the
LAN administrator acts as the single point of contact for the NOC to
provide a good communications channel for information and ensure
efficient coordination of problem resolution. This method of
delegating responsibility provides for a high level of service for
each LAN and optimally uses the time of NOC staff to provide
economies of scale.
Network Information Center (NIC)
The Network Information Center (NIC) provides information and
support services to facilitate the use of the network. The NIC
often provides a help-desk service to answer questions about use of
the network, references to useful resources and training in new
tools or applications. The NIC may also provide services such as an
on-line directory of network users and their electronic mail
addresses, bulletin board services of information and notices about
the network and on-line training materials. These NIC services
could be provided on a school district or County level. Most of the
information would not be site specific and can be delivered
electronically using electronic mail, electronic conferencing, on-
line bulletin boards or other document delivery mechanisms. These
types of services may be well suited for a school or school district
librarian.
Other types of support services may be performed by NIC personnel
such as maintenance of the electronic mail system or Postmaster
duties, coordination of an on-line bulletin board or campuswide
information system (CWIS) and management of an on-line conferencing
system. These duties are more technical in nature and will require
technical staff to maintain them.
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Postmaster
Every organization which uses electronic mail should have an
Electronic Mail Postmaster and a mailbox, postmaster, for the
receipt of messages regarding use of the electronic mail system,
mail problems and general inquiries about reaching people within the
organization. The Postmaster is responsible for reading postmaster
mail and responding to inquiries. These duties can be performed by
non-technical staff with forwarding of messages to the appropriate
technical support person as required.
CWIS Administrator
Campuswide information systems or bulletin boards are one of the
most useful applications on the network. These systems allow people
to share timely notices, documents and other resources with large
groups of people. These systems typically provide a hierarchical or
tree like structure of menus that lead to on-line documents or other
services. Common types of information include deadline notices,
grant announcements, training schedules, lists of available
resources such as videos in a library or reference materials.
[Figure 7: Distributed Network Information Servers]
Information need not be stored all in one location. Figure 7 shows
a set of distributed servers. These servers can receive new
information automatically from a central server and can also contain
information generated locally that may pertain only to the local
school. Users of the information need not know where the
information is stored: the information access software will present
choices on an integrated menu.
A CWIS or bulletin board must have an administrator or sponsor to
oversee the design and maintenance of the system so that it is easy
to navigate and find information, provides a professional
presentation of information and ensures that information remains
timely and relevant. This function can be performed by NIC staff,
or trained librarians or administrative staff as appropriate.
Management of On-line Conferences
On-line conferences provide a way for groups of people to share
information, discuss ideas and pose questions. Conferences usually
are set up to serve the needs of a group of people sharing a common
interest. For example, an on-line conference might be established
for teachers to discuss a new science teaching framework or a
teacher may establish a conference for the discussion of the Civil
War as part of an American History class. Some conferences are on-
going and may exist for years. Others are short term and may exist
for only one semester. Conferences may be created using the
electronic mail system or a facility called Usenet News.
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On-line conferencing systems require a server computer on the
network that collects messages posted to a conference and
distributes them when requested. Usually these systems are managed
by a systems administrator and someone must configure the system to
establish and delete groups upon request. Other management duties
include scheduling the deletion of old messages and archiving
especially valuable conversations. Typically these duties are
performed by a systems administrator or technical staff.
Staffing Considerations
The duties described above do not necessarily require hiring new
staff and they may be shared by people already within an
organization. Small schools or districts may rely on County Office
of Education Information Systems staff to perform all functions.
Larger schools or districts may have staff to take on any
combination of duties and rely on the County Office of Education for
others. Access to the network and the use of electronic
communications allows people throughout the organization to perform
these functions remotely. The assignment of responsibility for any
of these duties is flexible and should be approached with the goal
of providing the highest quality of service in the most cost
effective and workable manner.
VI. References
Honey, Margaret, Henriquez, Andres, "Telecommunications and K-12
Educators: Findings from a National Survey", Bank Street
College of Education, New York, NY, 1993.
Susan Estrada, "Connecting to the Internet", O Reilly & Associates,
Inc. (ISBN 1-56592-061-9)
Carole Teach, editor, "Building the Future: K-12 Network Technology
Planning Guide", California Department of Education, Research,
Evaluation & Technology Division, 1994.
VII Special Thanks
Special thanks to Brian Lloyd of Lloyd Internetworking, Inc.
for his contributions to this document. Brian was one of the
contributors to the California Department of Education "K-12
Network Technology Planning Guide" which served as the motivation
for writing most of this document. Brian contributed significantly
to Section II, "Rationale for the Use of Internet Protocols" and
thoroughly reviewed Section III, "A Technical Model for School
Networks", providing valuable feedback.
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VIII. Authors Addresses
Joan C. Gargano
Information Technology
Distributed Computing Analysis and Support
University of California
Davis, CA 95616
jcgargano@ucdavis.edu
David L. Wasley
Data Communication & Network Services
Information Systems and Technology
University of California
Berkeley, CA 94720
dlw@berkeley.edu
This Internet Draft expires December 31, 1994.
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