Fiber delivers bandwidth and flexibility

The Intermountain Network and Scientific Computation Center (INSCC) at the University of Utah (Salt Lake City) serves as a temporary home to research groups requiring high-performance computing and networking needs. The collocation promotes multidisciplinary research and facilitates high-speed access to the university`s Center for High Performance Computing as well as other universities and national supercomputing centers. Recent research projects include the Center for the Simulation of Acciden

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Air-blown fiber lets research center satisfy high-tech guests` demands for bandwidth.

Terri Dixon

Sumitomo Electric Lightwave Corp.

The Intermountain Network and Scientific Computation Center (INSCC) at the University of Utah (Salt Lake City) serves as a temporary home to research groups requiring high-performance computing and networking needs. The collocation promotes multidisciplinary research and facilitates high-speed access to the university`s Center for High Performance Computing as well as other universities and national supercomputing centers. Recent research projects include the Center for the Simulation of Accidental Fires and Explosions as part of the Department of Energy`s Accelerated Strategic Computing Initiative, and ongoing work in meteorology, physics, chemical engineering, and mathematics, among others.

"Within the inscc building, the interdisciplinary nature of the research requires a very flexible design for fiber-to-the-work-areas," says Dan Patterson, registered communications distribution designer (RCDD) and the university`s director of telecommunications. "For any given research project, the network engineers may use the fiber to transit anything from high-speed data to uncompressed video and Fibre Channel access to their servers."

The transitory nature of research projects conducted within the center called for a flexible solution to deliver fiber to modular workstations, according to Patterson. "As researchers complete projects and move out, new researchers involved in new projects move in. Under a conventional networking scenario, we would be spending an inordinate amount of time and money terminating and reconnecting fiber to comply with our new guests` data requirements and cubicle configurations."

Patterson took a page from the university`s pioneering work in adopting air-blown fiber (ABF) infrastructures to devise a flexible, cost-effective means of delivering fiber to workstations within the INSCC. "Eight years of experience with ABF at the university has proved that it is unmatched in enabling us to accommodate ongoing moves, adds, and changes across the campus," comments Patterson. "We`ve built on this experience by crafting an innovative solution for the computation center."

ABF technology uses compressed air or nitrogen to blow lightweight optical-fiber bundles through predefined routes. The infrastructure comprises rugged, flexible, standards-compliant tube cables containing up to 19 coded tube cells. The cells are joined in tube distribution units (TDUS) or junction boxes by using simple push-fit connectors to achieve a through route between the network hub and the application.

In virtually all circumstances, tube cable is installed with more cells than are required at the outset to allow room for expansion. Unused cells are capped within the tdus. Once the infrastructure is in place, lightweight optical-fiber tube bundles are blown through the cells in splice-free runs between the computer room and the application. Installations can be handled by a crew of two; blowing rates are typically 150 feet per minute. Network expansion is accommodated by extending tube cables from the nearest TDU. Fiber changes are accommodated via unused cells or by blowing out old fiber--which can be reused elsewhere--and blowing in new.

"The center`s floor plan consists of multiple cubicle configurations that contain four to six workspaces," Patterson explains. "Our goal was to deliver up to 18 fibers to each cubicle configuration in such a way that our guests would have `plug-and-play` access to their specific data requirements. We selected a zone network topology as the most efficient means of achieving the goal."

To accomplish this, the installation crew installed four TDUs in the ceiling of each of three floors of the four-story inscc building. Each TDU is connected to the intermediate crossconnect on that floor by means of a seven-cell plenum-rated tube cable, each cell of which can accommodate an 18-fiber bundle.

"We then installed two-cell plenum-rated tube cables to connect the tdus to multimedia outlets dedicated to each cubicle configuration," Patterson says. "The design allows us to blow a maximum of 36 fibers to each cubicle configuration directly from the main crossconnect to the multimedia outlet in splice-free, stress-free runs. It also allows us to reconfigure the network at will by supplying singlemode, multimode, 62.5- or 50-micron fiber--whatever the user requests."

Workstation wallplates can be served either by fiber patch cords or by fiber harnesses connected to the multimedia outlets. From the INSCC, access is provided to the main university network via an underground abf infrastructure based largely on six-cell laminated aluminum polyethylene tube cable. This particular portion of the University of Utah`s abf infrastructure has one of the two longest runs in the system: 5900 feet.

"By incorporating abf technology into the inscc infrastructure, we`ve created a research `hotel` that lets us quickly customize the size and type of fiber to meet guests` specifications," Patterson says. "A conventional fiber system, with all it signifies in terms of multiple pulling and splicing operations, would substantially increase the cost of each network change and at the same time risk degrading our network`s performance."

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From ceiling-mounted TDUs, two-cell plenum-rated tube cables termi-nate at multimedia outlets serving workstation clusters. The tubes carry fiber bundles containing up to 18 singlemode or multimode 62.5- or 50-micron fibers. Optical-fiber patch cords or harnesses (on the other side of the workstation wall) deliver communications to and from individual workstations. The white cables bring telephone and electrical service to the workstation cluster.

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At the University of Utah`s Intermountain Network and Scientific Computation Center, Sumitono Electric Lightwave`s FutureFlex ABF System is routed in a zone network topology. This configuration is repeated on three floors of the four-story research building.

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Dan Patterson, rcdd and director of telecommunications at the University of Utah, stands near an air-blown fiber (ABF) intermediate crossconnect. ABF tube cables (black) serve as the conduit to distribute ABF bundles from the main crossconnect to ceiling-mounted tube distribution units that, in turn, feed workstation cubicle clusters.

Terri Dixon is an application engineer at Sumitomo Electric Lightwave Corp. (Research Triangle Park, NC).

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