Childs Consulting Associates, Inc.

From the MEDIA SPECTRUM, vol 22, no. 3, article by John W. Childs,Ph.D., and Jeffrey L. Wale, M.Ed., of Childs Consulting Associates,Inc. Glossary of terms used added.

Local Area Network (LAN) and Wide Area Network (WAN)Telecommunications - Today and Tomorrow

Four considerations must be addressed in designing school data telecommunications networks:

1) Why are we seeking telecommunications connections among computer workstations?

2) What technology will we select to implement our local area network (LAN) and/or wide area network (WAN)?

3) What are the anticipated costs to install and operate the selected system?

4) When will we need to significantly alter, upgrade, or replace the system? (What is the educationally-useful life of the system?)

During the past ten years, Childs Consulting Associates, Inc. has assisted more than 100 clients in arriving at decisions about these four considerations for more than 300 separate school facilities. This article is based on that experience and the authors' perspectives on current and future (3-5 years) school needs and available technologies.

Consideration Number One: Why Are We Seeking Telecommunications Connections Among Computer Workstations?

First, why network? Historically, the purpose of administrative or instructional workstation local area networks was to achieve file and printer sharing. Practical experience suggests that networking for these two purposes alone is not sufficient to justify the costs involved. When considering a LAN implementation, the most critical consideration is the extent of the need to share work within an actual application. In the context of direct use of computers for subject matter instruction (integrated learning system) a LAN becomes essential to sharing the instructional application. When computers are primarily used by students and teachers as personal productivity tools, networking may add very little value. However, as newer instructional applications develop - such as collaborative software for students and teachers, teacher / administrator support software, on-line library / media card catalogs, abstract and full text information resources (UMI, etc.) - networking becomes necessary for effective use.

Once a school district or institution installs LANs in its buildings, it is reasonable to expect that a need to interconnect the LANs to form a private WAN soon will emerge - perhaps even before all buildings have LANs! Historically, the greatest need for WAN-type interconnection has resulted from administrative data communications needs - business, personnel, student personnel records, and daily communication (e-mail). Mini- and mainframe computers were able to serve most of these needs when the number of workstations remained low and relatively slow modem communication between buildings seemed adequate. (The dominant connection medium was / is dedicated telephone lines.) Because LANs run at a much higher speed - 10 Mbps vs. 1200 - 9600 Kbps - and have many more work stations, WANs require much larger capacities today: they need to be high speed information backbones - usually capable of up to 100 Mbps.

Today, and tomorrow, one of the primary purposes for the WAN is to provide economical Internet access. Fast, clean, efficient access to the Internet - particularly web servers - requires the technology of a high speed WAN. A district that carefully checks costs of separate dial up or individual building-direct connections to Internet will quickly find that any significant use - beyond 90 minutes per-school-day per connection - is not economical with dial-up facilities. Most dial-up connections - even those rated at 28.8 Kbps - do not support more than a single user at any given time. When a WAN connects all of a district's facilities, a high speed connection to the Internet (T-1 or greater) becomes cost effective for high levels of use. Current estimates indicate that when simultaneous active connection to web sources reaches about 12, T-1 speeds are needed to support reasonable workstation response times.

Do your faculty / staff / students have needs to share work on-line? Would on-line support materials be useful to your faculty / students? Would on-line administrative data make your administration / faculty / staff more efficient? Is Internet access important to your faculty / students? When you answer the "Why are we seeking a network?" question with positive responses to these kinds of applications, you have a need for LANs and WAN technology.

Consideration Number 2: What Technology Will We Select to Implement Our Local Area Network (LAN) and/or Wide Area Network (WAN)?

The second important network consideration concerns the particular technology that will be used to implement the LAN and/or WAN. Here, a wide variety of circumstances impact the selection. There simply isn't a single "best" technology and/or method to achieve an individual building or district solution.

Local area network choices range from simple networking products to ethernet / token ring, and on to FDDI and ATM. (Please see accompanying glossary article for quick definitions of these terms and acronyms). The fundamental issue in any networking technology is projecting the type and volume of traffic the network will handle. All too often, our colleagues have attempted to select the fastest possible technology within their budget capacity. Usually, this approach is driven by the fear that a "one shot opportunity exists" and may never return. Other times, we have seen a pattern of trying to jump ahead of current and short-term use in order to be prepared for an undefined future need.

Our experience in more than 5,000 networked workstations is that careful analysis of real need for a defined period of time (i.e. 3-5 years) results in a more realistic selection of network (LAN and WAN) capacity. There are many baseband (originally token ring), serial, modem, and ethernet (early 2 Mbps) networks effectively meeting educational needs. Today, a general description of a minimum new LAN calls for either 10 BaseT ethernet or 16 Mbps token ring. Approximately two-thirds of current new LANs installed in Michigan use a wiring infrastructure of UTP Category 5 cable installed to EIA / TIA 568 and IEEE 802.3 standards. Nearly all of these installations use equipment and software implementing 10 BaseT ethernet.

WAN technology is a bit more varied. Currently, the majority of all WAN connections are still carried over telephone circuits (leased dedicated lines or dial up) and are running at speeds from 9600 Kbps through 1.5 Mbps (T-1). Several districts' WANs are carried over fiber optic cable. These WANs have a basic minimum backbone capacity of 100 Mbps. In many cases, however, the backbone capacity is divided into a mix of T-1, 10 Mbps ethernet and/or 16 Mbps token ring channels. All of the backbone fiber optic WANs require a multiplexor and fiber transmitters. These devices are necessary to transform and package the electrical signals to light - and back from light to electrical signals.

Many vendors sell implementing equipment. At this time, for efficiency and reliability, it is essential to have the same manufacturer's equipment on each end of a circuit. WANs can be configured as rings, hub-to-node, bus and cluster, etc. In designing the WAN, it is very important to have accurate projections of WAN traffic. Educational environments do not match business and industrial environments in traffic demand, pattern, or regularity. Educational environments typically produce sudden high levels of demand followed by extremely low demand. In a LAN environment, for example, where applications are drawn from the fileserver and teachers in several classrooms with 4-6 workstations or a lab with 24 workstations start applications at the beginning of a class period, the load can quickly exceed the capacity of the most capable LAN. This "load" problem needs to be carefully assessed in planning both the LAN and the WAN. In determining "load," the following elements need to be considered: types of software to be used on the network, the size of "loadable chunks" of programs, the numbers of persons who will load applications at the exact same time, and the estimated amount of response time to elapse before classroom work is disrupted.

FDDI and ATM were mentioned earlier. Each of these technologies offers promise for future high speed connections in both LANs and WANs. Today, each carries a significant increase in acquisition cost over other methods. Additionally, each is implemented essentially as a single manufacturer solution - i.e., one manufacturer's switch will not necessarily perform well with another manufacturer's switch. Within a single district, either FDDI or ATM may soon be a viable alternative. Recently, we evaluated a district-wide ATM switch solution in contrast to implementing separate telephone and data network facilities. Separate facilities to adequately meet the district's needs came to a bit over $600,000. The ATM solution came to $1,600,000.

Today, full integration of data, voice, and video (ATM) is costly and may not add value to classrooms that still lack adequate end devices. Advanced network technologies may need to wait until basic instructional and administrative needs are achieved. We do believe, however, that full integration of data, voice, and video will occur for most schools within five years.

The task of determining the appropriate LAN/WAN implementing technology is complex. Most districts will find their own solution through careful study, consultant assistance, and vendor-supplied information.

Consideration Number 3: What Are the Anticipated Costs to Install and Operate the Selected System?

The third consideration is a perpetual concern - "What will it cost?" Over time, we have looked at LAN and WAN costs in several different ways. One view is to simply add up the initial acquisition cost and divide it by the points served. This usually generates a basic LAN cost ranging from $400 - $800 per point of use - admittedly, quite a range in price. The low end probably is adequate for many situations. This provides fileserver, cabling, network card, and network software. It assumes at least 60 workstations in the LAN - $24,000. The high end of the range allows for difficult installation, larger fileserver and printserver capabilities, managed network components, and more expensive network cards, hubs, transceivers, etc. - $48,000 for 60 workstations.

It is more difficult to estimate a standard range of cost for adding WAN capabilities between two or more LANs located in separate buildings. Our experience with WANs between buildings on the same campus / property (less than 5,000 feet) is that the cost is in the range of $12,000 - $18,000 per site. A significant variable is the distance between the sites. The cost elements are router / multiplexor, cable (fiber, coax, copper twisted pair), and building entrance conduit. A general estimate for lengthier connections among buildings on separate sites is $16,000 per mile of aerial fiber cable, $20,000 per mile of underground fiber cable, and, in both cases, the addition of right-of-way acquisition cost, legal fees, pole attachment fees, and make-ready fees.

Recently, two additional effective WAN connection technologies have begun to emerge: 1) 4 Mbps spread spectrum radio connections - range is line-of-site to 3-9 miles, and 2) direct satellite broadcast data links. The latter is cost effective only when the WAN must cover a large number of square miles and connect a limited number of sites - i.e., 1,500+ square miles and 12-22 sites. While the initial cost is quite small, the operating cost is currently about $60 per hour, per site on a 24 hour, 360 days-per-year contract. Because schools need only 6 to 9 hours per day of transmission time, the effective cost is $180 per hour, per site. This technology is currently available at data rates between 384 Kbps and 1.5 Mbps (T-1). Several remarketing firms are now trying to construct "repackaging" sites that will provide lower costs per hour and increase usage for more users.

The elements that determine cost are constantly changing. Suppliers of hardware, software, and network connection services constantly alter pricing. Each new installation requires a careful cost / benefit analysis that is specific to the time frame in which the technology will be installed.

Consideration Number 4: When Will We Need to Significantly Alter, Upgrade, or Replace the System?

Our fourth, and final, consideration is "When will we need to significantly alter, upgrade, or replace the system?" (What is the educationally-useful life of the system?) This requires a very speculative comment. During the past five years, we have seen teachers, students, and administrators outgrow the capabilities of newly installed technology in two to three years. At the personal computer workstation, the need to upgrade / replace has been nearly constant at the two-year life. However, five million Apple IIes are still in school district inventories. Many are no longer used, but many have been repurposed and are providing useful instruction.

Network infrastructure - cable and conduit - currently has up to a 40-year life cycle. The network electronics, if regular software upgrades are performed, will generally have a ten year life.

We have suggested in several presentations to school business officers that a careful analysis of the school district's invested technology base can be used to project the annual operating costs - including repair, maintenance, use support, and long-term replacement. Our existing data suggests that the percentage of an existing investment that is required for long-term technology effectiveness is 7% annually for repair and maintenance - and 22% for use support, software, and long-term upgrade. To state this another way, if you have $100,000 invested, you will need $29,000 annually.

Many new networking technology opportunities will emerge in the near future. Everyone involved in technology applications will need to frequently "restudy" what is available, how it can meet old or new needs, and what the likely costs will be to sustain a technology infrastructure.

The comments in this article are those of the authors alone. The data and opinions presented here are not attributable to anyone else. We believe the breadth of our experience and the extent of data available to us may be unique. We are pleased to have had an opportunity to share our thoughts with the readers of Media Spectrum.

About the authors:

John Childs, Ph.D., President, and Jeffrey Wale, M.Ed.,Vice President, operate Childs Consulting Associates, Inc., a firm located at 29516 Southfield Rd., Southfield, Michigan, 48076. Their company has consulted with public and private schools and colleges in Michigan, various other states (including Alaska), and Singapore in the design and development of technology systems. Working independently of any vendor or manufacturer, they assist school administrators, faculty, and staff in seeking the most cost-effective ways of answering their technology and curriculum-related needs. Their company's philosophy states, in part, that "Technology is not the solution in itself, but a means to reaching excellence in education."