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.
Many organizations concerned with K-12 educational issues and the planningfor the use of technology recognize the value of data communicationsthroughout the educational system. State sponsored documents such as theCalifornia Department of Education, Srategic Plan for Information Technologyrecommend the planning of voice, video and data networks to support learningand educational administration, but they do not provide specific technicaldirection.
The institutions that built the Internet and connected early in itsdevelopment are early adopters of technology, with technical staff dedicatedto the planning for and implementation of leading edge technology. The K-12community traditionally has not had this level of staffing available fortelecommunications planning. This document is intended to bridge that gapand provides a recommended technical direction, an introduction to the rolethe Internet now plays in K-12 education and technical guidelines forbuilding a campus data communications infrastructure that providesinternetworking services and connections to the Internet.
For a more general introduction to the Internet and its applications anduses, the reader is referred to any of the references listed in the followingRFCs:
In 1993, the Bank Street College of Education conducted a survey of 550educators who are actively involved in using telecommunications. (Honey,Margaret, Henriquez, Andres, "Telecommunications and K-12 Educators: Findingsfrom a National Survey," Bank Street College of Education, New York, NY,1993.) The survey looked at a wide variety of ways telecommunicationstechnology is used in K-12 education. Their findings on Internet usage aresummarized below.
"Slightly less than half of these educators have accessto the Internet, which is supplied most frequently by a university computeror educational service."
"Internet services are used almost twice as oftenfor professional activities as for student learning activities."
"Sendinge-mail is the most common use of the Internet, followed by accessing news andbulletin boards and gaining access to remote computers."
The followingchart shows the percentage of respondents that use each network applicationto support professional and student activities.
Applications Professional Student Activities ActivitiesElectronic mail 91 79News or bulletin board 63 50Remote access to other computers 48 32Database access 36 31File transfer 34 19The value of the Internet and its explosive growth are a direct result of thecomputer communications technology used on the network. The same networkdesign principals and computer communications protocols (TCP/IP) used on theInternet can be used within a school district to build campuswide networks.This is standard practice within higher education, and increasingly in K-12schools as well. The benefits of the TCP/IP protocols are listed below.
The benefits of internetworking technology have been demonstrated throughtwenty years of use by thousands of organizations. This same experience alsoprovides tested technical models for network design that can be adapted toK-12 campuswide networking in schools of all sizes and technical development.
The vision of a modern communications network serving all primary andsecondary schools has been articulated and discussed in many forums. Manyschools and a few school districts have implemented ad hoc network systems inresponse to their own perception of the importance of this resource. Thissection of the Internet School Networking (ISN) Working Group RFC presents astandard network implementation model to assist county offices of educationand school districts in their planning so that all such implementations willbe compatible with each other and with national networking plans intended toenrich K-12 education.
The future goal of "an integrated voice, data, and video network extending toevery classroom" is exciting, but so far from what exists today that theinvestment in time and dollars required to realize such a goal will begreater than most districts can muster in the near term. We suggest that agreat deal can be done immediately, with relatively few dollars, to providemodern communications systems in and between all schools around the nation.
Our present goal is to define a highly functional, homogeneous, and wellsupported network system that could interconnect all K-12 schools anddistrict, county, and statewide offices and that will enable teachers andadministrators to begin to use new communications tools and network-basedinformation resources. It takes considerable time to adapt curricula andother programs to take full advantage of new technology. Through the use ofstandard models for implementation of current network technologies, schoolscan begin this process now.
Many states have already developed communications services for their schools.A notable example is Texas which provides terminal access to centralinformation resources from every classroom over a statewide network.Modem-accessible systems are available in many states that serve to encourageteachers 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 anticipationof emerging and future bandwidth intensive information resource applicationsand the functionality that they will require, we believe it is essential toprovide direct network access to the National Research and Education Network(NREN) Internet (The Internet is a "network of networks" that interconnectsinstitutions of higher education, research labs, government agencies, and arapidly growing number of technology and information vendors.) from computersin 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 moderncomputers. These protocols support a very wide variety of applications, fromelectronic messaging to client/server data access. The use of Internetprotocols will ensure that all networked computers will have direct access tothe vast range of existing information and education resources on theInternet, as well as to the emerging National Information Infrastructure.
1) Any physical infrastructure development should be general and flexibleenough to be reused as technology improves. For example, a school officemight have a simple terminal today which could be wired to a network adapterserving the school building. Later a Macintosh, DOS, or Windows-based PCmight replace the terminal, and the type of connection to the network wouldchange 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 to40% of the cost of individual network hookups;
2) Existing computers and terminals in schools and district offices should beintegrated as much as possible into the communication system. This installedbase represents a large investment, albeit in many cases a somewhat dated setof equipment. Wholesale replacement of that base would be a large additionalburden on funding resources.
A consequence of the above is that the user interface and the servicesavailable will vary depending on the type of equipment used to access thenetwork. For example, DOS PCs, Macintosh computers, or Unix workstationswould be connected directly to Local Area Networks (LANs) and would beprovided with communications software to support a broad set of functions,many of which will have graphical user interfaces and will make use ofclient/server technology. Apple-II computers, "dumb" terminals, or othersuch devices could be connected to intelligent network hubs that would allowaccess to network server computers or information resources, but almostcertainly will not support the full range of functionality provided by adirect network connection. In the short term, this is a limitation that wemust accept;
3) Network servers will be located where they can be managed and supported,and also provide access paths with adequate bandwidth. A system ofhierarchical servers should be created in larger school districts, withautomatic transfer of common information from a central system to thesecondary systems each night, or at appropriate intervals. Local serverswill allow each school to provide on-line information particular to itsprograms and community. This model optimizes use of network bandwidth aswell;
4) School interconnect topologies (links) must be both cost effective andmanageable. Communication between schools, district offices, county officesof education, and the State Department of Education must be reliable and ofsufficient capacity to support the primary applications as well as allowdevelopment of new applications.
Capacity is measured both by total data traffic volume and by responsetime when information is requested over the network. Reliability is measuredby 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 morethan 10% of the communications bandwidth is used during a typical work day.This is intended to leave adequate capacity for good response time to shortterm communication demands.
Many schools already have some form of communications infrastructure inplace. In some cases this infrastructure can be adapted to newertechnologies; in other cases it may have to be replaced over time. Theseissues are explored further following presentation of the basic model thatserves as a guideline for future communications system development.
The strategic decision to use Internet protocols in developing schoolnetworks provides the opportunity to avoid the major expense of building newstatewide backbone infrastructures in the near term.
Interconnection of schools, districts, county offices of education andthe State Department of Education can be accomplished by acquiring Internetconnection service from any of the existing Internet service providers in thestate. ("Connecting to the Internet", Susan Estrada, O'Reilly &Associates, Inc. (ISBN 1-56592- 061-9) lists Internet service providers inCalifornia and the nation.) It is critical that Internet connection servicemeet criteria for reliability and capacity but connection to any Internetservice provider will provide communication capability to all other Internetsubscribers within the state, the nation, and the world.
Internet technology is designed to allow very flexible intersitetopologies, but a hierarchical topology is the simplest to engineer.Generally this will mean hierarchical connection of school facilities todistrict offices, in many cases further aggregated at county offices, andfinally a link to an Internet service provider. Coordination of circuitservices and a single point of connection to an Internet service providerserves both to minimize overall costs and increase opportunities to make useof newer technologies.
The basic school network implementation model is quite simple: create alocal area network (LAN) within each school building or cluster of buildings,provide at least one network server for that LAN, interconnect that LAN withthe local school district offices where a similar LAN should be installed andwhere centrally managed information resources should exist, and connect thedistrict offices to the nearest Internet service provider, possibly throughthe county office of education.
Primary technical support for network monitoring and problem resolution,and for managing network resource servers should come from the district orcounty offices initially to avoid unnecessary duplication at the local level.As expertise is developed at the local level, more of the responsibility fordaily operation and problem resolution can be assumed by individual schools.
It is impossible to cover all conceivable scenarios for implementation ofthis model in specific schools. However, it is possible to state generalprinciples that should be followed in designing school networkimplementations. The discussion below is organized into sectionscorresponding to the basic model summarized in the previous paragraph. Itincludes a description of the general principles that are important to eachlevel of the implementation.
A "school" is used here to mean a building or cluster of buildings that aremanaged as a unit and typically are on contiguous, district owned property.Implementation of a LAN in this setting will involve installation of acabling system to distribute the network throughout the structure(s),installation of premise wiring to support connections of computers andterminals to the network distribution system, installation of one or morenetwork server machines in a central location (Other protocols, such asAppleTalk 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 resourceservers.), and provision of a network router and telecommunications circuitor 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 moreexpensive and it is not available for as wide a range of computers.) Bothare quite inexpensive and easy to install and maintain. Ethernet isadaptable to most modern computers and is built-in to high performanceworkstations such as Sun, Hewlett-Packard, SGI, or Digital EquipmentCorporation computers. LocalTalk is built-in to all Macintosh computers andis adaptable to DOS PC computers as well. Ethernet is roughly 20 to 40 timesfaster than LocalTalk. Therefore ethernet is recommended for all computerconnections, when possible, and for the school LAN "backbone" or networkdistribution system.
Individual computers will require network or communications adapters andappropriate software. Table 1 gives basic recommendations for the computersmost commonly found in schools. Basic communications software is availablein the public domain for many personal computers at no cost. Moresophisticated software is being developed by a number of vendors forapplications such as electronic mail, distance learning, and multimediadatabase access. For example, the California Technology Project isdeveloping very easy to use software for Macintosh and DOS or Windows PCcomputers that will enable access to a wide variety of information resourcesand services. Schools should look at all the available software and basechoices on required functionality and support costs as well as acquisitioncosts.
In locations where computers will be purchased, the choice of computertype should be driven by the availability of software for the particularapplication(s) to be supported. Almost all modern computers can be attachedto the type of network described in this document.
Equipment Type Network Adapter Communication SoftwareSimple terminal "Network Access Server" Built-in to the
located centrally. networkaccess server.Apple II, Amiga, Serial asynchronous Serial communicationsTandy, Commodore, port that will allow software that emulatesolder IBM PCs, etc. connection to the a simple terminal. above.Newer IBM PC Ethernet adapter card 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 equivalentMacintosh (external) and shared plus "telnet" andcomputers LocalTalk to ethernet "ftp". For example, router, for example the NCSA Telnet. Shiva FastPath. Additional software for special applications, e.g., "electronic mail client."Newer Apple May use same as the Same as the above.Macintosh above. For highercomputers 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
A major component of the implementation will be installation of cablingto connect individual computers or clusters of computers to the LAN. Therecommended 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 ofcomputers, typically found in a teaching lab or library, may beinterconnected within the room where they are installed, and the clusterconnected to the hub site with a single cable as shown in Figures 3 & 4.
The recommended premise wiring is "unshielded twisted pair" (UTP) wirethat meets the Electronic Industries Association (EIA) category 5 standardsfor high speed data communication service. (See EIA/TIA-568 "CommercialBuilding Telecommunications Wiring Standard.") While 2 pair cable may beadequate for most purposes, industry standards recommend installation of 4pair cable. The difference in cost is minimal so we recommend installationof 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 initialcost is amajor factor. Such jacks can be replaced with category 5 versionslater as needed.) located near the computer. The other end terminates on astandard "110 distribution block" (In older sites, M66 distribution blocksmay already be installed. These can be used for the time being but will notsupport newer higher speed technologies.) at the hub site utility closet. Alabeling scheme must be chosen and strictly adhered to so that cables can beidentified 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 telephoneservices. It is essential that a separate wall area be set aside within thecloset for data service interconnections. Typically there will be a "field"of interconnect blocks for termination of all premise wires, another fieldfor termination of trunk cables (used for low speed data terminals), and athird field for hub equipment ports. Interconnections between premise wiringblocks and hub or trunk blocks are installed as needed in order to providethe appropriate service to each location where communication service isrequired.
[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 aqualified data wiring contractor. This is a critical aspect of the programand must be planned and installed professionally with both current and futurerequirements in mind. (See "Virtual Schoolhouse - A Report to theLegislature on Distribution Infrastructures for Advanced Technologies in theConstruction of New Schools, K through 12" (Department of General Services,State of California, February, 1993) for example conduit and utility closetplans.) To be prepared for future distribution of video signals, schoolnetwork planners should consider installation of RG-59 coaxial cable to thoselocations where video may be required at the same time that the UTP premisewiring is being installed. The coaxial cable would terminate on a wall platemounted "F" connector in the classroom, and would be left unterminated in theutility closet. Future technologies may support video signals over othermedia so the installation of RG-59 cable should be limited to near termpotential requirements.
It will be cost effective to install premise wiring to as many locationsas might ever serve a computer. This will include administrative offices aswell as classrooms, laboratories as well as libraries. In high densitylocations such as offices, consideration should be given to installation oftwo UTP cables to each outlet location in order to provide the potential forseveral computers or workstations. Terminating both cables on the same wallplate will add little to the overall wiring project costs and will addgreatly to the flexibility of the system. Premise wiring that is not to beused initially will not be connected to any electronics in the hub site.
Hub sites should be utility closets or other protected, non-occupiedareas. Hub sites can be created by construction of small closets or cabinetsin low use areas. A hub site must be located within 300 feet of anyconnection. Typically, multiple hub sites are required in large ormulti-story buildings.
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, then10-base-T wiring can be used from a central hub to connect each hub site, asshown in Figure 5. If longer distances are required, either thin-net orstandard thick ethernet can be used. Fiber optic cable can be used ifdistance requires it and funding permits. (If fiber optic cable isinstalled, consideration should be given to including both multimode fiberfor current and future data requirements and single mode fiber for video andfuture very high speed data systems.) Specific design of the "backbone"network distribution system will depend on the layout of the buildings to beserved.
With proper design as many as 250 computers can be connected to a singleethernet segment. Most often the practical maximum number will be much lowerthan 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. Beyondthat size the network must be subdivided using "subnetworks". Design of asuch a system is not difficult, but is beyond the scope of this document.
The network distribution system cabling should include unshieldedmulti-pair trunk cabling as well as ethernet trunk cabling. The multi-pairtrunk cable will be needed to connect terminals or older computers emulatingterminals to a central "network access server" (NAS). A typical NAS canserve from 8 to 128 such connections. It is most cost effective to provideone per LAN, if needed. The NAS connects directly to the ethernet LAN.
It is highly recommended that each school install a "network server" tosupport local storage of commonly used information, software, electronicmail, and other functions that may require high speed communication to theusers computer. Since the connection to the outside network will be muchslower than the school LAN, it will be most efficient to access informationlocally. In particular, software that is to be shared among the schoolscomputers must be stored locally since it would be very tedious to transferit across the slower external link. The network server will be connecteddirectly to the ethernet network.
The location of the server should be chosen carefully to ensure itsprotection from abuse and environmental damage. Traditionally the schoollibrary is the focus of information gathering and storage activities and manyschool libraries have clusters of computers or terminals already installed.The library would be a very logical place to locate the network servercomputer. The Network Router (see below) might also be located there if asuitable utility space is not available.
The network server will be a small but powerful computer with a largeamount of disk storage capacity, typically 1-4 gigabytes. It will runsoftware capable of supporting access by a large number of userssimultaneously. It could also support dial-in access from teachers orstudents homes using standard inexpensive modems. (Access control with userauthentication is essential if dial-in service is to be provided.) If morethan 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 adistrict, a single central modem pool maintainted at the district officeswill be the most cost effective.
A single communication circuit will connect the school LAN to the localschool district offices. In the school, there will be a Network Routerattached between the LAN and this circuit. On the LAN side, the connectionwill be a typical ethernet cable. On the external side, the connection willdepend on the type of communication circuit used, as discussed in step 2below.
All schools within a district should be connected individually to thenetwork router at the school district offices. This "star topology" will bemuch easier to manage and the capacity of each schools connection can beincreased appropriately as needs change.
Several standard communication circuit services may be used to effectthis connection. The least expensive for situations where only limited useis needed will be dial-up using high speed modems. However, this type ofconnection is not recommended for serious usage due to its very limitedcapacity. Also, since most schools receive telephone service under businesstariffs, usage will be measured and the cost will be dependent on how longthe 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 recommendedsince they will allow unattended access to and from the school network at allhours. This will be particularly important if information files are to bedown-loaded during the night to local network servers or teachers andstudents 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 andas tariffs are modified. The exact costs must be determined by contactinglocal communications service providers.
Total cost must take into account the equipment needed at each locationas well.
Type of Circuit Data Rate Relative costVoice grade leased 20 kilobits per sec (Kb/s) modest*telephone lineADN-56 56 Kb/s highISDN, where 64 or 128 Kb/s modest**availableLow power radio 64 to 256 Kb/s high startup costFrame Relay 56 Kb/s to 1.5 Mb/s modest to highDS1 1.5 megabits per sec very high
Frame Relay communication services are becoming available in many areas.Frame Relay is a shared, packet based data transport service. A school sitewould contract for Frame Relay service as part of a larger service group thatincludes the school district office and may include the Internet serviceprovider. 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 beordered (each member orders a connection to the common service) and thecapacity offered to each member can be upgraded independently. Also, in manyareas the cost of Frame Relay service is not dependent on distance to theservice provider which will make service to rural schools much less expensivethan equivalent services. Overall system costs will be minimized since thecentral router at the district office will need fewer connections.
If Frame Relay is chosen, the overall service group must be carefullyengineered. For example, since all schools would share the connection to thedistrict office (and possibly to the Internet service provider), that must bea high capacity connection. For the initial design, the aggregate capacityof all school links should notor there may be noticeable congestion andvariability in response times across the system. There are many otherfactors that must be considered as well, such as the virtual connectiontopology and how best to connect to an Internet service provider. Therefore,it is recommended that an experienced network engineer be utilized to developan operational plan for Frame Relay if it is chosen as the schoolinterconnection service.
Future options for interconnecting schools and district offices will include:
(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 begenerally higher than those indicated in Table 2. The cost for the CATVoption may be negotiable as part of the local CATV contract with thecommunity.
As demands for network speed develop due to heavy use of multimedia orother bandwidth intensive application, higher speed communications circuitscan replace the initial circuits with minimal change in the equipment or LAN.This gives great flexibility in tailoring service to funding levels andapplication needs.
The School District offices should form the focal point forinterconnection of all schools in the district. Within the District offices,network operations can be monitored and problem resolution managed. One ormore network servers can provide essential network support as well as centralarchiving of common information and software.
A critical role of the district office will be to manage Internet "DomainName System" (DNS) (See STD 13, RFCs 1034, 1035 for the full explanation ofDNS, and also, RFC 1480.) service for the districts schools. DNS is requiredof all Internet networks. It defines the basic network level identity ofeach computer, workstation, server, and active network component. Thisfunction is described more fully below under Network Management andOperational Monitoring.
The district offices should be wired in a manner similar to a typicalschool, as shown above. This will allow teachers, superintendents, andprincipals to communicate and share information easily. In addition, an NASconnected to a central pool of modems could provide dial-in access to thedistrict network.
Connection of the entire school district to the Internet will take placethrough the district office interconnect site, as shown in Figure 6. Thishierarchical model can be extended another level to interconnection of theschool district offices through the county office of education facilities.Many administrative information resources could be located at the countylevel, and there might be cost savings if the entire county connects to anInternet service provider through a single point. The bandwidth required forthis single connection, however, will be much greater than that required foreach school district since traffic will be aggregated.
This hierarchical topology also provides a logical model for networksupport and information resource management. The school district or countyoffices can provide continuous monitoring of the network and provide highlevel technical expertise for problem resolution, relieving the individualschools of this burden. Interactions with communications circuit providersand Internet service providers will be more effective if handled through acentral "trouble desk". Similarly, it is highly desirable that network usershave 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 thoseshown in Table 2 above. The higher speed services should be considered iftraffic demands increase and funding permits. Circuit costs usually will belowest 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 ondistance. The Internet connection will require a high quality router thatcan beconfigured to interact correctly with the service providers routers.In most cases, this can be the same router used to support the local schoolconnections.
[Figure 6: Interconnection of schools to the Internet through localSchool District Offices]
Many schools have developed LAN systems in support of particular classroomactivities or administrative functions. In some cases the technologies usedare not those recommended for new installations. If these older LAN systemsare capable of transporting Internet protocols they may be integrated into anew LAN system and replaced later as funding permits.
For example, IEEE 802.5 Token Ring is often used to interconnect DOSPC-type computers and IBM minicomputer servers. Token Ring networks cantransport Internet protocols and software is available for DOS computers tosupport basic Internet functions. Many Internet routers support optionalToken Ring adapters. This is the recommended way that existing Token RingLANs can be integrated into a wider school LAN system in order to extendInternet information resources to those PC users.
Another example is a Novell Network system using ethernet as a LAN. Theethernet LAN, if implemented well, is perfectly capable of transportingInternet protocols as well as Novell protocols, simultaneously. Each PC orMacintosh can be given software that will allow both Novell and Internetservices to be used as needed. This coexistence is important so that, forexample, a person using a PC that depends on the Novell server for disk filespace can transfer a large file from a remote Internet server to the PCspseudo-disk. It also permits each user to run client software such as Eudora(electronic mail), Gopher (information services), and Mosaic (World Wide Webinformation services) which require direct Internet access. To integrate theNovell ethernet LAN into the wider school LAN system a simple ethernetrepeater can be used in a manner similar to Figure 3 above.
An alternative to supporting both protocols that is sometimes suggestedin cases such as the one cited above in which a network server already existsis to use the server as a "network application gateway". This approach isstrongly discouraged. It is essential that each computer and workstationsupport Internet protocol data communication directly so that modernclient/server applications can be supported where the server or servers maybe located anywhere on the Internet. The "gateway" approach severelyrestricts the workstations potential ability to access multimedia and otherimportant information resources.
Some technologies, such as "arcnet," may not be capable of supportingInternet protocols but may offer "terminal emulation" shared access tosomething like a "modem pool". The modem adapter might be rewired to connectto ports on a network access server instead. This would provide simpleaccess to information resources for the arcnet users.
In any case, older LAN technologies should not be expanded and should bephased out as funding permits. It is critical that there be a relativelyhomogeneous installed base of technology in order that new applications ofinformation resources can be provided to the entire school community.
All networks require some level of network management in order to ensurereliable service. Monitoring of the health of the network can help identifyproblems before they become detrimental to network users. It also can helppredict trends in traffic patterns and volume.
Internet technology network management consists primarily of determiningthe proper routing parameters for optimal and reliable network operation,assignment of network Internet Protocol (IP) addresses and maintenance of anetwork-accessible database of node names corresponding to each address (SeeRFC 1480 for a discussion of Internet naming conventions for schoolnetworks.), and monitoring the daily operation of the network. Thesefunctions typically are performed by the staff of a Network Operations Center(NOC).
The Internet Domain Name System (DNS) is the mechanism for documenting anddistributing information about the name and address of each computer attachedto the network (network nodes). The DNS service is provided by software thatruns on the main network server. It uses a database that is created andmaintained by the NOC staff.
An Internet address is the numerical identifier for a node and it must beunique among all nodes associated with the network. Furthermore, if thenetwork is to be part of the global Internet, all addresses must belegitimate 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 ofteneasier for computer users to remember and usethe node names rather than thenumerical addresses. In particular, electronic mail addresses use nodenames. DNS node names are hierarchical and by appropriately using thishierarchy "subdomains" can be assigned to each school site or districtoffice. In this way, naming can be structured to be flexible as well asmeaningful in the context of the whole organization.
A plan for the assignment of IP network addresses and node names shouldbe developed early in the planning for the network installation. Initially,the database serving the DNS should reside on the "district server" so thatthere is one site at which all assignments are officially registered. As thenetwork grows and expertise is developed, secondary DNS service can be run onthe servers at larger school sites.
The main DNS server for the district should be located as close to theInternet connection (topologically) as possible. This proximity is to helpensure that network problems within the district network will have minimalimpact on access to the server. This design is illustrated in Figure 1 wherethe district server is on an ethernet connected directly to the maindistribution router.
Associated with the assignment of node names and addresses should be adatabase of specific information about the computers connected to thenetwork. When trying to resolve problems or answer user questions, it isvery important to know where the computers and other nodes are located, whattype of computer and software are in use, and what type of network connectionis installed. With proper software this database can be used to extract theDNS database discussed above.
1) Constant observation of the "health" of the network, networkcomponents, and external network connectivity. Standard Simple NetworkManagement Protocol (SNMP) support is built-in to most active componentstoday. Even network servers and workstations can be monitored in this way.Operations staff can be provided with network monitoring stations that willdisplay alerts immediately upon detecting a wide variety of problems oranomalies;
2) Collection of statistics on the performance of the network and patterns oftraffic in order to identify needed enhancements or re-engineering. Usingthe same SNMP capabilities mentioned above, data on packet forwarding andtotal traffic volume can e collected and used to generate periodic reports onnetwork utilization;
3) More rapid problem resolution. When problems do occur, SNMP tools canhelp to pinpoint the source of the problem(s). Such problems includetransient routing anomalies, DNS query failures, or even attempts at breakinginto network accessible host computers.
Since network management and monitoring is a technically demanding task andrequires special equipment and software, it should be a centralized functionin the initial design of school network systems, as discussed above.
The model for school network implementation described above is based onbroad experience with this technology in higher education and administrativeenvironments. Many schools have already installed networks very similar tothis model. We believe that it is a practical first step towards bringing apowerful resource to bear for enriching all of the nations school programs.
None of the suggestions above preclude or postpone in any way futuredevelopment of an integrated voice, data, and video network for the nationsschools. Use of existing Internet carriers does not in any way precludefuture development of a separate "backbone" for the K-12 community if such a"backbone" is determined to be cost effective or required for enhancedfunctionality. Rather, the infrastructure recommended above can be thefoundation at the local level in preparation for future high capacitynetworks.
The installation of a campuswide network or Internet connectivity willalso require a commitment to ongoing network support and its related resourcerequirements. There are two major areas of network support, networkoperations and user services. These support functions are usually performedthrough the establishment of a Network Operations Center (NOC) and NetworkInformation Center (NIC), however both functions can be performed by the sameindividual or groups of individuals.
The Network Operations Center (NOC) oversees the performance of thephysical network and some of its software support systems. The staff mayinstall networks, configure network devices and provide configurations forcomputers attached to an organization-wide network. Real-time monitoring ofthe network can be performed using the Simple Network Management Protocol andmany vendors produce monitoring systems that graphically display networkperformance, log events and usage, and produce trouble tickets. The use ofthis type of network monitoring allows NOC staff to quickly detect problemsand greatly reduces the personnel required to perform this function. Routinemonitoring of the network can help to anticipate problems before they developand lead to reconfigurations and upgrades as indicated. If problems doarise, 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 andmaintain the Domain Nameservice (DNS) for their organization. DomainNameservice is a machine registry service that runs on a network server andenables access to machines by easy to remember names, rather than a networknumber. DNS is required for any organization connected to the Internet andcritical to the establishment of an electronic mail system.
It is most cost effective to have the Network Operation Center serve anentire organization or region. In order to ensure timely service all the wayout to the most remote LAN, it is recommended that an organization assignlocal area network administration duties to on-site personnel to interactwith NOC staff and assist with the maintenance of the network. In the caseof a school district, administrative support staff, teachers, librarians orschool based technical staff can each take responsibility for a LAN or groupof 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 ifNOC staff need to be notified. If so, the LAN administrator acts as thesingle point of contact for the NOC to provide a good communications channelfor information and ensure efficient coordination of problem resolution.This method of delegating responsibility provides for a high level of servicefor each LAN and optimally uses the time of NOC staff to provide economies ofscale.
The Network Information Center (NIC) provides information and supportservices to facilitate the use of the network. The NIC often provides ahelp-desk service to answer questions about use of the network, references touseful resources and training in new tools or applications. The NIC may alsoprovide services such as an on-line directory of network users and theirelectronic mail addresses, bulletin board services of information and noticesabout the network and on-line training materials. These NIC services couldbe provided on a school district or County level. Most of the informationwould not be site specific and can be delivered electronically usingelectronic mail, electronic conferencing, on-line bulletin boards or otherdocument delivery mechanisms. These types of services may be well suited fora school or school district librarian.
Other types of support services may be performed by NIC personnel such asmaintenance of the electronic mail system or Postmaster duties, coordinationof an on-line bulletin board or campuswide information system (CWIS) andmanagement of an on-line conferencing system. These duties are moretechnical in nature and will require technical staff to maintain them.
Every organization which uses electronic mail should have an ElectronicMail Postmaster and a mailbox, postmaster, for the receipt of messagesregarding use of the electronic mail system, mail problems and generalinquiries about reaching people within the organization. The Postmaster isresponsible for reading postmaster mail and responding to inquiries. Theseduties can be performed by non-technical staff with forwarding of messages tothe appropriate technical support person as required.
Campuswide information systems or bulletin boards are one of the mostuseful applications on the network. These systems allow people to sharetimely notices, documents and other resources with large groups of people.These systems typically provide a hierarchical or tree like structure ofmenus that lead to on-line documents or other services. Common types ofinformation include deadline notices, grant announcements, trainingschedules, lists of available resources such as videos in a library orreference materials.
[Figure 7: Distributed Network Information Servers]
Information need not be stored all in one location. Figure 7 shows a setof distributed servers. These servers can receive new informationautomatically from a central server and can also contain informationgenerated locally that may pertain only to the local school. Users of theinformation need not know where the information is stored: the informationaccess software will present choices on an integrated menu.
A CWIS or bulletin board must have an administrator or sponsor to overseethe design and maintenance of the system so that it is easy to navigate andfind information, provides a professional presentation of information andensures that information remains timely and relevant. This function can beperformed by NIC staff, or trained librarians or administrative staff asappropriate.
On-line conferences provide a way for groups of people to shareinformation, discuss ideas and pose questions. Conferences usually are setup to serve the needs of a group of people sharing a common interest. Forexample, an on-line conference might be established for teachers to discuss anew science teaching framework or a teacher may establish a conference forthe discussion of the Civil War as part of an American History class. Someconferences are on-going and may exist for years. Others are short term andmay exist for only one semester. Conferences may be created using theelectronic mail system or a facility called Usenet News.
On-line conferencing systems require a server computer on the networkthat collects messages posted to a conference and distributes them whenrequested. Usually these systems are managed by a systems administrator andsomeone must configure the system to establish and delete groups uponrequest. Other management duties include scheduling the deletion of oldmessages and archiving especially valuable conversations. Typically theseduties are performed by a systems administrator or technical staff.
The duties described above do not necessarily require hiring new staff andthey may be shared by people already within an organization. Small schoolsor districts may rely on County Office of Education Information Systems staffto perform all functions. Larger schools or districts may have staff to takeon any combination of duties and rely on the County Office of Education forothers.
Access to the network and the use of electronic communications allowspeople throughout the organization to perform these functions remotely. Theassignment of responsibility for any of these duties is flexible and shouldbe approached with the goal of providing the highest quality of service inthe most cost effective and workable manner.
Honey, Margaret, Henriquez, Andres, "Telecommunications and K-12Educators: Findings from a National Survey", Bank Street College ofEducation, 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 TechnologyPlanning Guide", California Department of Education, Research, Evaluation& Technology Division, 1994.
Special thanks to Brian Lloyd of Lloyd Internetworking, Inc. for hiscontributions to this document. Brian was one of the contributors to theCalifornia Department of Education "K-12 Network Technology Planning Guide"which served as the motivation for writing most of this document. Briancontributed significantly to Section II, "Rationale for the Use of InternetProtocols" and thoroughly reviewed Section III, "A Technical Model for SchoolNetworks", providing valuable feedback.
Security issues are not discussed in this memo.
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