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RFC 1709 - K-12 Internetworking Guidelines


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Network Working Group                                         J. Gargano
Request for Comments: 1709               University of California, Davis
FYI: 26                                                        D. Wasley
Category: Informational               University of California, Berkeley
                                                           November 1994

                    K-12 Internetworking Guidelines

Status Of This Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

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" (also FYI 18)
   1432    "Recent Internet Books"
   1462    "What is the Internet" (also FYI 20)
   1463    "Introducing the Internet - A Short Bibliograpy of
           Introductory Internetworking on Readings for the Network
           Novice" (also FYI 19)

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.
   (Honey, Margaret, Henriquez, Andres, "Telecommunications and K-12
   Educators: Findings from a National Survey," Bank Street College of
   Education, New York, NY, 1993.)  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."

        "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.

   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.

   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 Internet School Networking
   (ISN) Working Group 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 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 (The Internet is a "network of networks" that
   interconnects institutions of higher education, research labs,
   government agencies, and a rapidly growing number of technology and
   information vendors.) 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.

      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 PCs, Macintosh
      computers, or Unix workstations would be connected directly to
      Local Area Networks (LANs) and would be provided with
      communications 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,
   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.  ("Connecting to the
   Internet", Susan Estrada, O'Reilly & Associates, Inc. (ISBN 1-56592-
   061-9) lists Internet service providers in California and the
   nation.)  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.

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 (Other protocols, such as AppleTalk or Novells IPX,
   may be supported on a school's local area network (LAN) as needed for
   local function such as printer sharing or local resource servers.),
   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.  (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.)  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.

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 PCs, etc.   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, e.g.,
                                                "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 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.  (See
   EIA/TIA-568 "Commercial Building Telecommunications Wiring
   Standard.")  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
   (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.) located near the computer.  The
   other end terminates on a standard "110 distribution block" (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.) 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
   current and future requirements in mind.  (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, February,
   1993) for example conduit and utility closet plans.)  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,

   either thin-net or standard thick ethernet can be used.  Fiber optic
   cable can be used if distance requires it and funding permits.  (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.) Specific design of the "backbone" network
   distribution system will depend on the layout of the buildings to be
   served.

   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 users 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 schools 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 teachers
   or students homes using standard inexpensive modems.  (Access control
   with user authentication is essential if dial-in service is to be
   provided.)  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 schools
   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 schools 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.

Type of Circuit         Data Rate                       Relative cost
________________________________________________________________________

Voice grade leased      20 kilobits per sec             modest*
telephone line           (Kb/s)

ADN-56                  56 Kb/s                         high

ISDN, where              64 or 128 Kb/s                 modest**
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
________________________________________________________________________

* Measured service charges must be taken into account.
** At this time, most ISDN tarriffs include message unit charges
   which can make theuse of ISDN prohibitively expensive for
   full-time connectivity.

          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 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:

   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.

   (Many more options will become available as new technologies come to
   market.)

   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) (See STD 13, RFCs 1034, 1035 for the full
   explanation of DNS, and also, RFC 1480.) service for the districts
   schools.  DNS is required of all Internet networks.  It defines the
   basic 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 (At this time, SMDS services are not widely
   available.) 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 providers 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]

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 PCs 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

   workstations 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.

   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 (See RFC 1480 for a discussion of
   Internet naming conventions for school networks.), 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.

   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.

      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 nations 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
   nations 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.

   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.

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.

   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.

V.  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", OReilly & 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.

VI.  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.

VII.   Security Considerations

   Security issues are not discussed in this memo.

VIII. Authors' Addresses

   Joan C. Gargano
   Information Technology
   Distributed Computing Analysis and Support
   University of California
   Davis, CA   95616

   EMail: jcgargano@ucdavis.edu

   David L. Wasley
   Data Communication & Network Services
   Information Systems and Technology
   University of California
   Berkeley, CA   94720

   EMail: dlw@berkeley.edu

 

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