Fiber-to-the-desktop upgrade solves copper-cable communications deficiencies
A parts manufacturing plant overhauls its patchwork copper-based network with an all-fiber network and eliminates transmission-disruption problems
GEORGE H. SELLARD
CORNING INC.
When the inventor and leading manufacturer of optical fiber had to recable the data communications network in one of its manufacturing plants, Corning Inc. still grappled with the question of whether to install copper or fiber to meet the network performance needed--within budget constraints. After a lengthy cost-performance analysis, the company selected an all-fiber-optic cable solution.
The Erwin Manufacturing Facility, a part of Corning Inc., manufactures ceramic substrates for catalytic converters used in gas and diesel engines. Located in Erwin, NY, the plant encompasses approximately 500,000 square feet of floor space with 30-foot ceilings in the production areas. Business offices are clustered in various locations throughout the facility.
Over the years, a hybrid data communications network evolved at Erwin. In 1994, when network planners decided it was time for an overhaul, the plant`s network consisted of five segments connected by thick- and thin-wire coaxial cables, unshielded twisted-pair copper wiring, bridges, repeaters and a mix of network-support hardware. This patched network had no overall design objective, thereby making maintenance, testing and troubleshooting difficult.
Other network problems involved electrical noise signals generated throughout the plant. In particular, room-sized electromagnetic frequency generating dryers interfered with and sometimes disrupted network transmission. Moreover, the old coaxial-cable installation continually needed maintenance and did not conform to structured cabling. Lastly, the long cabling runs in the cavernous plant approached the inherent distance limitations of coaxial cable and copper wire.
Time to recable
For upgrading, network managers at Erwin preferred a plant data communications system that could provide a local area network connection to all desktops for file and device sharing. They also wanted a universal "learning desk" environment in which training software, such as for word processing and spreadsheet applications, could be delivered directly to employees` terminals. With training available at the desk rather than at a single learning laboratory, the managers felt that workers would be more apt to use and become adept with the software.
From the start, the Erwin network planners opted for optical fiber cabling and its high-bandwidth capacity. They knew that using fiber throughout the network would eliminate the transmission-disruption problems caused by the plant`s dryers, occupy less space--which was crucial because of limited duct space--and be easier to install because of its light weight.
On the debit side, though, the network planners believed that a fiber-optic solution would be too expensive for their tight operating budget. Consequently, they decided to rewire their facility with shielded twisted-pair copper wire and move to a 10Base-T data communications protocol. In fact, they had already begun running copper lines when Corning network consultants intervened.
Desktop goes fiber
The new network installation plan recommended by the Corning consultants specified fiber to the desktop using a centralized cabling architecture. In this network layout, all the data-processing electronics equipment resides in one location. From this single point, optical fiber cables run all the way to desktops either by way of two-fiber cables running directly to workstations or by high-fiber-count riser cables to passive crossconnects. From there, two-fiber cables run to work area outlets.
The fiber-optic centralized cabling design also helps simplify maintenance, testing and troubleshooting. Transmission-speed upgrades become fast, easy and economical by changing ports at the hub and network interface cards at the computer. The passive crossconnects take up little real estate, and unlike intermediate distribution frames containing active electronics, they require no power, air conditioning or grounding.
Another low-cost fiber-to-the-desk solution employs multi-user outlets, especially useful in a modular-furniture environment. A high-fiber-count cable (12 to 32 fibers, for instance) is run from a closet to a multi-user outlet fixed to a permanent structure, such as a supporting column, within open office space. Then, optical fiber patch cords are installed through the furniture raceways from the outlet to each user`s desktop. This approach is possible because optical fiber cable is not functionally restricted to the 3-meter limitation of Category 5 copper patch cords, nor are there any power separation requirements that hinder the installation of copper systems in modular furniture. Furthermore, the office can be reconfigured without disrupting the cabling infrastructure.
Using the centralized cabling design, Erwin was able to plan a fiber-to-the-desktop network at just a 3% cost premium over a comparable copper infrastructure. Considering the reductions in maintenance costs expected over time, the cost differential favors fiber.
"Besides, fiber has a longer life than copper," says Sharon A. Nutting, Erwin`s supervisor of integrated computer systems. "And it doesn`t look like copper is going to meet the 100-megabit-per-second speeds in a production environment that some have claimed it would. Strategically, optical fiber is the medium of choice."
Network in progress
The Erwin network overhaul comprises a five-phase project. The second phase is now in its final stages. Optical fiber cable has been run to nearly every office in the facility. Data electronics are housed in a single computer room within equipment cabinets containing fiber hubs. These hubs are daisy-chained and then connected to the existing thick-wire coaxial-cable backbone network This backbone will remain in operation until the replacement fiber-optic backbone is installed.
From the computer room, two-fiber cables run directly to work area outlets. In addition, four riser cables containing 24 Corning 62.5/125-micron multimode fibers run to an equipment room in the accounting department. Here, the riser cables are fusion-spliced to the workstation fibers. Spare fibers remain in each box for later fusion splicing or mechanical splicing to future stations.
In all, 214 work area outlets have been connected, with each outlet containing two ST connectors. These connectors require no epoxy or polishing, easing fiber-to-the-desk installation. A fiber-optic jumper cable is connected from the outlet box to the back panel of the personal computer or workstation.
According to Robert Mulks, technician/foreman of the installer company Communication Design Specialists, "The ST connectors have low loss and require only a few tools. The connectors are reliable and we usually replace only approximately 2% after testing."
In subsequent phases of the project, employees will be added to the network, and fiber-optic cable will be extended to other work areas around the sprawling plant. Adds Erwin`s Nutting, "We`re in a mass hook-up stage."
Despite the numerous advantages of fiber over copper, the Erwin network planners hesitated over the cost. "We had reservations," recalls Nutting, "but when we saw that a fiber-optic solution could be cost-competitive, too, we were sold." u
George H. Sellard is cable systems analyst of the Information Services Division at Corning Inc., Corning, NY.