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diff --git a/doc/rfc/rfc1709.txt b/doc/rfc/rfc1709.txt new file mode 100644 index 0000000..c9569aa --- /dev/null +++ b/doc/rfc/rfc1709.txt @@ -0,0 +1,1459 @@ + + + + + + +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) + + + + + +ISN Working Group [Page 1] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + +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. + + + +ISN Working Group [Page 2] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 3] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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. + + + + + +ISN Working Group [Page 4] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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. + + + + + + + + +ISN Working Group [Page 5] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + +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 + + + +ISN Working Group [Page 6] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 7] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 8] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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. + + + + + + + + + + + + + + + +ISN Working Group [Page 9] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + +Equipment Type Network Adapter Communication + Software +________________________________________________________________________ + +Simple terminal "Network Access Server" Built-in to the + located centrally. networkaccess server. + +Apple II, Amiga, Serial asynchronous Serial communications +Tandy, Commodore, port that will allow software that emulates +older IBM 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 + + + + + + +ISN Working Group [Page 10] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + +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] + + + + +ISN Working Group [Page 11] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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, + + + +ISN Working Group [Page 12] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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. + + + + + +ISN Working Group [Page 13] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 14] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 15] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 16] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 17] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 18] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 19] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 20] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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. + + + + + + + + + +ISN Working Group [Page 21] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + +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. + + + + + + + +ISN Working Group [Page 22] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + +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] + + + + + +ISN Working Group [Page 23] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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 + + + +ISN Working Group [Page 24] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + + 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. + + + + + + + + + + + + + + + + + + + + + + + + +ISN Working Group [Page 25] + +RFC 1709 K-12 Internetworking Guidelines November 1994 + + +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 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +ISN Working Group [Page 26] + |