Carrying data to more kinds of desktops

Th Cheri

Optical fiber is gaining popularity in LANs across myriad industries

BY Elizabeth Goldsmith

Factories, military bases, laboratories, universities, museums, primary schools, law firms, government agencies, and businesses are just some of the places where you'll find optical fiber carrying data all the way to the workstation. No longer just the province of "extreme" applications, optical fiber is becoming more popular in local area networks (LANs) in many industries as more high-bandwidth, high-speed protocols increase the demands of networks in every type of application.

To help users understand how multimode optical fiber can benefit their applications, the Fiber Optics LAN Sec tion (FOLS) of the Telecom muni cations Industry Association maintains a list of case histories on its Website ( Additional information on the installations discussed in this column can also be found there.

Why are network managers choosing multimode optical fiber over newer grades of twisted-pair copper? Over whelmingly, the answers are:

  • Fiber-based systems cost less now-at a time when new grades of copper are costing more-making fiber a cost-effective alternative for both new installations and rebuilds.
  • Fiber offers proven performance at higher speeds and virtually no system downtime.
  • Fiber is perceived as a medium that will support network requirements longer without the need to re-cable.
  • Centralized cabling offers a standards-compliant architecture that leverages the performance advantages of fiber.
  • New technologies such as small-form-factor (SFF) connectors are making fiber-based systems easier and more cost-effective to install.

So, where do you find fiber installed today? Network upgrades, new builds, and even networks that use both fiber and copper as they migrate to all-fiber solutions are a few examples that explain why these applications turned to fiber-based networks.

At the Susquehanna Pfaltzgraff Co. (York, PA) network managers chose optical fiber for performance reasons. They chose to upgrade their network, which served more than 500 internal customers in more than 19 separate buildings (some more than 100 years old), when some of the existing unshielded twisted pair (UTP) cabling could not be certified to 100-Mbit/sec performance.

Optical fiber not only gave them the performance they needed, but also helped them overcome some of the challenges inherent in the installation. The factory, which included kilns, presented a hot, high-humidity environment and included some very long cable runs. Susquehanna Pfaltzgraff used centralized cabling to help make installation cost-effective and take advantage of the long cable lengths made possible by fiber's high bandwidth. In addition to increasing the network's speed, installing fiber has also increased system reliability to over 99.99%, while maintenance is required about once every two months, with most of the work addressing server issues rather than infrastructure.

At the U.S. Special Operations Com mand at MacDill Air Force Base (Tampa, FL), optical fiber was initially chosen because of the medium's security, as the three networks installed here have both secret and top-secret classification. The medium's bandwidth is also important, since LAN applications include video, map-based graphics, and multimedia applications.

However, the Air Force realized other benefits, as well. First, by using centralized cabling, they were able to eliminate multiple communications closets, thereby making the system far less expensive. They've found the network very easy to maintain, allowing MIS managers to easily accommodate reorganizations, workstation moves, and rearrangements. And they feel secure that they have futureproofed their network for the foreseeable future.

The engineering laboratory at the Uni versity of Victoria in British Columbia uses both multimode optical fiber and Category 5 UTP cable. Currently, the LAN provides one dual optical-fiber port and one or two Category 5 data/voice ports to virtually all work and study-area positions. The university chose a multimedia approach to accommodate a large contingent of existing Ethernet networking equipment, but they expect to migrate to an all-fiber network over time. Fiber offers the university the capability to handle the very high-speed computer connections needed for multimedia, CAD/CAM, distributed computing, and other bandwidth-intensive computer and engineering applications.

The fiber portion of the LAN uses a centralized cabling network, with all the electronics and fiber connections in a main communications room. MIS managers expect that this arrangement will greatly simplify managing, rearranging, and moving workstations on the fiber portions of the network. Each dual-fiber cable goes from the main communications room all the way to the workstation in one continuous length (some over 200 m), without splices or interconnects.

At the J. Paul Getty Center (Brentwood, CA), the chief de signer selected optical fiber be cause he felt it was the best long-term investment for the facility-a decision bolstered by fiber's bandwidth, economics, flexibility, and reliability.

Although the primary decision driving the deployment of fiber was campus-wide bandwidth requirements, using fiber recovered more than $5 million in floor-space savings. That's because by centralizing electronics, museum designers essentially eliminated the use of distributed intermediate equipment rooms. These savings were more than enough to pay for the entire cabling system.

When the Minnesota Department of Revenue (DOR) in St. Paul moved into new office space, they left their copper cabling behind in favor of a LAN that takes fiber to desktops. The installation provides more than adequate bandwidth to handle the convergence of voice, data, and video at the desk. With a total of 2,310 desktop ports capable of 155-Mbit/sec throughput, the DOR can increase capacity in the building by more than 25%.

Although Category 5 UTP was presented as the "industry standard" during the planning stages of the project, system engineers were not confident that today's copper cable would be able to handle the high-bandwidth applications on the horizon. With multimode optical fiber, the DOR's network manager feels he has a solution that will carry the agency well into the 21st century. Using a centralized cabling infrastructure, the DOR also found the all-fiber solution to be economical, too. By permitting longer passive links between the electronics and the users' workstation, they were able to eliminate numerous telecommunications closets and minimize their investment in active electronics.

At Parsons Behle & Latimer, one of Utah's leading law firms, the systems engineer originally planned to install Category 5 UTP when the firm upgraded their twisted-pair infrastructure-with a plan to upgrade again in five years. But after conducting a detailed comparison of the installed costs of fiber and copper, the firm chose to take fiber to the desk at only a 16% premium over copper. The firm anticipates this cabling infrastructure will meet its needs for 15-20 years before having to worry about the expense and disruption of recabling.

The Parsons Behle & Latimer instal lation not only uses a centralized cabl ing architecture, it also takes advantage of the cost savings afforded by SFF connectors and media converters. SFF connectors al low greater port density be cause of their small footprint. They are also easier to terminate than conventional connectors or copper jacks. Using media converters helped save the firm money by allowing them to leverage their investment in their existing electronics.

Lower costs enabled by fiber-friendly architectures and new technologies mean that fiber will continue to migrate out of the backbone into the horizontal. With the cost of all-fiber-based systems now coming close to those of Category 5 UTP, network managers can focus on performance, reliability, and network longevity to make their decisions-making fiber the right choice for all LANs with performance challenges, whatever the industry or application.

Elizabeth Goldsmith writes on behalf of the TIA Fiber Optics LAN Section (FOLS). Member companies include 3M, AMP, Allied Telesyn, Berk-Tek, Belden Wire & Cable, CommScope, Corning, LANCAST, Lucent Technologies, MicroLinear, Ortronics, Panduit, Siecor, Siemon Co., SpecTran, Sumitomo Electric Lightwave, and Transition Networks. For more information from FOLS, please vistit Cheri

Cheri Podzimek, vice president of marketing at Transition Networks (Minneapolis), co-wrote the "Premises Networks" column in the May 2000 issue of Lightwave, page 20, and we inadvertently published the photo of another periodic Lightwave columnist, Eve L. Varma. We apologize to Cheri and Eve for this faux pas-and to our readers for any confusion the error may have caused.

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