rfc1709.txt

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   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



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   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



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   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



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   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



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   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



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   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.