A Tutorial on Centralized Optical Fiber Cabling Networks

Mary Spring Corning, Perspection Inc.

Description

Figure 1 In the traditional cabling design, cables run to active telecommunications closets locatedA Tutorial on within 328 feet of users. Each closet contains active network electronics. Therefore, the spacerequires power, air-conditioning and grounding. Category 5 copper cables connect closets to users.CentralizedOptical FiberCabling Networks HUBHUBHUBby Douglas E. Harshbargerand George SellardHUBHUBll-optical fiber centralizedlocal area networks (LANs)HUBA are the present wave in net-work cabling. In increasing num-bers, network planners are takingHUBadvantage of optical fiber’s virtuallyFIBERunlimited bandwidth and low sig-OPTICSHUBnal loss (attenuation) to implementa centralized design. All data elec-tronics are housed in a single loca-HUBtion and optical fiber cablesprovide direct connections to everyworkstation outlet in the network. n Passive patch panels use jumper of failure and reduced telecommu-Contrast this with the traditional and intrabuilding cables in inter- nications closet build-out costs.design, where active electronics, mediate closets. Consolidating network electronics,hubs, concentrators and switches With direct connections between analyzers, uninterruptible powerare housed in telecommunications network hardware and desktops, sources (UPSs), cross-connects andclosets that are distributed through- maintenance and troubleshooting servers in a single communicationsout a building and within 328 feet are vastly ...

Informations

• Publié par: Naphug
• Nombre de lectures: 76
• Langue: English

Extrait

ATutorialon Centralized Optical Fiber Cabling Networks

by Douglas E. Harshbarger and George Sellard

ll-optical fiber centralized wo A In increasing num-rk cabling. local area networks (LANs) are the present wave in net- bers, network planners are taking advantage of optical fiber’s virtually FIBER unlimited bandwidth and low sig- OPTICS nal loss (attenuation) to implement a centralized design.All data elec- tronics are housed in a single loca- tion and optical fiber cables provide direct connections to every workstation outlet in the network. Contrast this with the traditional design, where active electronics, hubs, concentrators and switches are housed in telecommunications closets that are distributed through- out a building and within 328 feet of all users. The fiber optic centralized cabling design is simplicity itself. The main cross-connect is linked to desktops in one of three ways: nPull through, or homerun cabling, which involves passing cables through intermediate closets to the desktop without the use of patch panels. nSplice cabling which involves splicing to jumper cables in intermediate closets and then linking to the desktop.

Figure 1In the traditional cabling design, cables run to active telecommunications closets located within 328 feet of users.Each closet contains active network electronics.Therefore, the space requires power, air-conditioning and grounding.Category 5 copper cables connect closets to users.

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nPassive patch panels use jumper and intrabuilding cables in inter- mediate closets. With direct connections between network hardware and desktops, maintenance and troubleshooting are vastly simplified.Speed upgrades are quick, easy, economi- cal and many merely involve a change of ports at the hub and net- work interface cards (NICs) at the desktop computer.The passive patch panels require little real estate. Also,unlike intermediate dis- tribution frames containing active electronics, passive patch panels require no power, air-conditioning or grounding. The centralized optical fiber design offers many benefits, includ- ing improved security, fewer points

of failure and reduced telecommu- nications closet build-out costs. Consolidating network electronics, analyzers, uninterruptible power sources (UPSs), cross-connects and servers in a single communications closet greatly simplifies local area network (LAN) management, pro- vides more efficient use of hub ports and allows for simple imple- mentation of various network appli- cations. Thedeployment of redundant systems, including redundant UPSs, also reduces con- cerns over single points of failure. Moreover, the centralized optical fiber cabling design provides a cost- effective alternative to the tradi- tional design because using fewer active components lowers overall costs. Maintenancecosts over the

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Figure 2In the centralized optical fiber cabling design, fiber to the desktop is achieved with direct connections between a single hub and each user.All data electronics are housed in one location.

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lifetime of the network will be reduced as well. Cableinstallation and testing are simplified, further reducing initial costs. Centralized network designs simplify installations, reducinginstallation time and labor. All terminations are performed at the centralized cross-connect, where all data electronics are housed. “Everything coming back to one point cuts down on labor,”said Darryl Wolford, president of Communication Design Spe- cialists, Weedsport, N.Y.Wolford has installed numerous centralized networks. “With the centralized network, you don’t have to direct your crew so much.This minimizes time and cuts down on labor.” Network testing also is made easier by the centralized design.Because of the sin- gle termination point, the process is espe- cially quick and uncomplicated.Also, test procedures for optical fiber networks, which are well-established and field- proven, are specified in Annex H,“Optical Fiber Link Performance Testing,”of ANSI/TIA/EIA 568A, the Commercial Build- ing Telecommunications Cabling Standard. “Testing fiber is a lot less labor-inten- sive than it is for Category 5 copper,”Wol- ford said,“and we test both all the time. To

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Figure 3The centralized design is simple, yet it allows for flexibility in cabling configu- ration.

Home Run Cabling

Network at American Video

test Category 5 takes us about 15 minutes. It takes two minutes for fiber.” Standards for centralized fiber net- works are well along in development.In September 1995, the TR-41.8.1 committee of TIA approved publication of Telecom- munications Systems Bulletin (TSB) 72, Centralized Optical Fiber Cabling Guide- lines, to supplement the Commercial Building Telecommunications Cabling Standard ANSI/TIA/EIA 568A regarding the design and installation of centralized optical fiber cabling.Fall 1998 will see the publication of ANSI/TIA/EIA 568B, which will include standards for central- ized cabling. Case In Point:A Centralized

An optical fiber centralized network recently was completed at the new home of American Video Glass Company (AV), which manufactures glass panels and fun- nels for television picture tubes.The newly completed 500,000-square-foot fac- tory in Mount Pleasant, Pa., is equipped with a state-of-the-art information tech- nology and controls infrastructure, the foundation of which is a centralized

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cabling, fiber-to-the-desktop network designed by Sellard Communications. Two issues drove the decision to install an all-fiber network at American Video Glass. Mostcritically, planners wanted to be assured of sufficient information-car- rying capacity to run whatever applica- tions they might require in the not-so-distant future.Fiber’s virtually unlimited bandwidth provides that assur- ance. Also,with plant expansion and cabling moves on the horizon, the robust and flexible fiber optic centralized cabling plant will allow for quick and easy moves and changes. At the center of the centralized net- work at AV is a computer room with net- work hubs and servers housed in a two-story core structure in the middle of the factory.From this point, Siecor MIC cables, each containing 24 Corning 62.5/125 micron multimode optical fibers, run to the telecommunications closets. Siecortwo-fiber MIC cables con- nect closets with workstations inside the building. Inaddition, three Siecor FREEDM cables, each with 24 Corning multimode fibers, travel from one telecommunication closet directly to clos-

ets in three outbuildings. FREEDM cable is an indoor/outdoor cable that eliminates the need for a transi- tion splice at building entrance points. Due to a special loose tube design, the cable is riser-rated, allowing AV to extend its centralized network to three buildings near the central factory by way of aerial conduit. With no splicing along the way, each cable runs directly from a telecom- munications closet, outdoors, into another building and straight to other telecommu- nications closets. This capability reduces installation costs by eliminating the mate- rial and labor expenses associated with the building entrance transitions. Without optical fiber none of this would be possible. Other media, particularly cop- per, cannot meet the bandwidth and atten- uation requirements at the distances used in a centralized cabling design such as the one at American Video Glass. “It’s more cost feasible to use the fiber optic centralized cabling design because there are no closet build-outs and minimal maintenance,” saidRalph DiNinno, IT and controls manager.With no active elec- tronics distributed throughout the net- work, there are no large closets to build and maintain — just small cabinets con-

taining wall-mounted splice centers. This reduction in multiple closets played a major part in reducing the cost premium traditionally associated with fiber. Upfront savings were important to AV network designers. But even more crucial was the opportunity to future proof their cabling infrastructure against soaring bandwidth demands by installing optical fiber throughout their facility.The huge bandwidth offered by optical fiber has already paid off at AV, according to DiNin- no. Hehas gained considerable peace of mind from knowing that his network will not suffer bandwidth bottlenecks any time soon. “Fact is, we’re a brand-new company,” DiNinno said.“We have limited history and information about our network and capacity requirements.So, when we designed the network, we installed Ether- net knowing that the bandwidth available on optical fiber could support a change to new electronics, such as ATM (asynchro- nous transfer mode), as our needs grow.” Expanding the network or adding appli- cations will not present problems either. “If we decide to deploy additional work- stations,” DiNinnosaid, “thefiber is there to do it. ”

“Also, long term maintenance is an issue,” DiNinnosaid. “Butwith the cen- tralized cabling and fiber, maintenance and troubleshooting do not require going out to hubs. We have homeruns, so trou- bleshooting is easy.We just test through the hubs in the central computer room.” DiNinno is confident that installing an all-fiber network at American Video Glass has been a smart move strategically, com- mercially and financially. “The fiber allowed us to go with a very simple cable design,”DiNinno said. “That eliminated a lot of trouble.The central- ized design is excellent.” By taking advantage of fiber’s superior distance performance, network designers can reduce the number of electronic com- ponents and increase their port utiliza- tion. Furthermore,the single point administration made possible through a centralized system increases ease and pro- ductivity while reducing cost. CBM Douglas E.Harshbarger is market development engineering manager, premises systems, for Corning Inc.; George Sellard is president of Sellard Communications. Specialthanks to Patrick Scanlon of Rochester Institute of Technology for his assistance.

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