Cost overrules technology in data networks
End users opt for established data communications networks and applications, and resist changes to fiber-optic transmission and switching technologies unless product, cable and signal rate costs are reasonable
dave powell
Often, in data networking and communications, end users` practical concerns lag behind the industry`s state-of-the-art standards and technology developments. Fiber optics is no exception. In most applications, users do not plan or install networks to showcase the latest fiber technologies or communications protocols. Instead, they prefer the basic technologies that move data as fast as needed--and at the lowest cost.
Fiber-optic cabling is chosen only when it offers a more practical, cost-effective solution than copper, wireless or public data services. Some data users will not consider advanced synchronous optical network, asynchronous transfer mode or integrated services digital network data communications services until they become much cheaper. Here are some typical data user applications.
On the banks of San Francisco Bay, the Golden Gate Transit District manages the area`s ferry and bus services. It also collects traffic and revenue data from toll plazas on the Golden Gate Bridge. Tim Kirschbaum, data communications technician, says the company changed its data communications network to fiber-optic cables because San Francisco`s weather is not copper-friendly. "Prior to 1991, we used copper, but exposure to wind, rain and salty air severely limited copper for the data speeds we wanted."
So the company replaced the copper network with three pairs of multimode fiber. One fiber pair carries traffic from three dozen remote users to a central computer center next to Kirschbaum`s trailer. These users work in the Ferry-services and Bus-services Divisions in nearby towns. The first leg of the data link uses line-of-sight microwave to transfer data to an administration building near the bridge. From there, data is switched onto 1000 feet of underground fiber that feeds into a fiber-optic multiplexer connected to the central computer.
Users transmit bus- and ferry-maintenance records, ticket-sales figures and audit information. The fiber`s bandwidth allows them to run Microsoft Windows applications from central network servers, which has helped decrease software costs. The second fiber pair serves local personal computer users, and the third fiber pair serves as a spare.
The short distances involved multimode fiber. "I can stand in one place and see all our buildings at the bridge," says Kirschbaum. "There was no need for singlemode fiber. Also, with singlemode, you have to deal with lasers and expensive hardware."
The cost of the fiber-optic network was approximately $7500. But it was not the first fiber installation at the bridge: Twelve strands of 15-year-old plastic-coated fiber have carried motor vehicle counts from the Golden Gate Bridge toll plazas. "This plastic-coated fiber is old," Kirschbaum adds. "You have to be careful with the stuff." This fiber-optic cable goes to a computer in the administration building.
This fiber-optic network has enabled Kirschbaum to avoid buying additional $10,000 data terminal controllers for the central computer. "Before, we couldn`t add users to the computer without buying more data terminal controllers," he says. "Now, the network gives us almost unlimited access to the computer."
Kirschbaum also saved $500 in fiber-termination costs. "Some of our 4-inch conduit was wide enough to pull fiber with connectors attached," he says, "so I ordered the fiber pre-terminated. This is risky, because you have to pull it terminated. I covered the connector ends, attached the rope further down the cable and taped the connector ends to the rope to eliminate tension. It saved $50 per cable end."
Traffic before installation
Genesee Hospital, Rochester, NY, does not have an enterprise-wide data backbone network. Its fiber-optic cabling is limited to an 1800-foot server-to-server link supporting six local area network users. "But we are starting to plan for an expanded fiber backbone within the next year," says Doug Schoenheit, PC analyst for management systems.
The two-part fiber-optic cable connects a server in the computer room in one building to another server located in a building one block away. This cable link runs through innerduct in the two buildings, and then through conduit under a street and a parking garage. At a curbside interface unit, the four-strand fiber from the computer room is expanded into a 12-strand, gel-filled cable.
The fiber carries 10-megabit-per-second Ethernet traffic. "According to Monarch Communications, our local contractor, singlemode fiber would have given us greater bandwidth but fewer possible application paths. So, we went with multimode fiber," Schoenheit says. "And we went with 12 strands in case we want to carry video or other applications." The future backbone will also carry traffic from security-badge readers throughout the complex.
He adds, "Our contractor recommended against using twisted-pair copper and repeaters, since the signal would be knocked down at each repeater. Also, fiber would not be affected by thunderstorms, lightning and temperature extremes outside the building."
The cost of the fiber-optic network was $7200, including installation and hardware. Running parallel is an RG-32 coaxial-cable line, which gives users at dumb terminals direct access to the hospital`s computer mainframe. The coaxial-cable link cost only $2600, according to Schoenheit. "But fiber costs are coming a lot closer to copper. There is now only a 10% to 15% price differential over copper."
Fiber hits the road
The New York State Thruway Authority negotiated a public/private partnership ro develop, integrate and support a fiber-optic network for high-speed digital voice, data and video communications along the Thruway`s 641-mile route and rights-of-way.
The Thruway Authority Board approved a $55 million 20-year agreement with Metropolitan Fiber Services, or MFS, Network Technologies Inc. of Omaha, NB. MFS will market network and conduit usage to communications providers to finance the project and to provide the Thruway Authority with an ongoing source of revenue.
According to Mike Keogh, director of general services for the New York State Thruway Authority, "We are doing this to create additional revenue streams for the thruway by renting our fiber right-of-way to other users." The project could also address state-government telephone and data communications needs, including those of the Thruway Authority.
Because of the different business goals for this fiber network (and its multiple potential customers), a multi-innerduct conduit system will be installed. This approach would allow the state government, MFS and third parties to use separate ducts. Keogh estimates that at least 48 strands of fiber will be used. The data protocols have not yet been selected.
He does not think the constant road construction along the thruway will endanger the network. "The conduit will be placed as far off the road as possible," he explains. "In most locations, our right-of-way is more than 400 feet wide, so we can bury conduit in a secure area. We also know what bridges will be repaired in the future and what lanes are to be expanded, and can plan around those future problem areas."
The agreement stipulates that the Thruway Authority will receive 20% of the network`s gross revenues for the first 15 years of the 20-year agreement, and 50% during the remaining five years. Potential users of the system include local-exchange, interexchange, competitive-access and cable-TV providers, in addition to paging, cellular and personal communications services companies.
The network will also be used by the Thruway Authority to handle its own voice, data and video transmissions, saving the agency between $1 million and $2 million annually in telecommunications costs.
The project will be built in segments, with the bulk anticipated to be finished in two years. The New York City-Albany corridor is targeted to be completed first.
The Thruway Authority will be responsible for internal project management and construction insspection, identifying locations of buried utilities and identifying easements. These tasks will be handled by existing staff and facilities.
The fiber network will support an ongoing modernization of the state`s toll-collection systems. "We would like all toll transactions to be transmitted electronically," Keogh explains. For example, an on-the-fly toll-collection system, called E-Zpass, is already operational in the lower Hudson River Valley and around Buffalo. This system collects tolls automatically from radio transmitters within vehicles while they drive past toll stations.
The new fiber-optic network will also provide the video bandwidth needed to enforce this system, Keogh adds. "It will capture and forward video images of any vehicle that drives through the E-Zpass lane with an expired pass or no pass at all. We`re gradually moving this application upstate, and as we do, it requires massive amounts of data and video bandwidth over fiber."
College campus plans
Since 1991, Paul Ladd, director of management information systems, has been overseeing the installation of a 1300-line Ethernet network linking eight buildings in Suffolk University`s Boston campus. Some buildings are connected by fiber-based digital carrier system, level one (1.554-Mbit/sec) lines installed by Nynex, the local telephone company. Other buildings are reached by fiber cables installed under a parking lot. Still other buildings are linked to the fiber backbone using radio transceivers. Applications include TCP/IP Internet access, Netware LAN traffic, Unix computer file transfers, online library services and access to CD-ROM research databases.
When Ladd began planning the network, he compared rates and services from several providers. "We looked at public services, alternative access providers, microwave bypasses and wireless vendors," he explains. "We even talked to Western Union about renting conduit under the street and to MFS Communications about connecting to its Boston fiber loop. But we are located in Boston`s Beacon Hill area, which is not on the loop. I had hoped to have several options, but the competition wasn`t--and still isn`t-- there."
In fact, Nynex offered a costly proposal for running fiber to Suffolk`s campus. "It would have cost approximately $100,000 per year over five years, just to connect eight buildings," Ladd says. He admits that the existing solution is limited to Ethernet speeds, and that Nynex would have installed faster links. "But, when the time came to go to ATM, we would have needed to reinvest in upgrading Nynex`s fiber multiplexers and switches anyway, so the cost-justification wasn`t there."
Within several multifloor buildings, Ladd uses multimode fiber as the primary riser backbone. It was chosen for its scalable bandwidth. "With multimode, you can change the electronics at each end to run at a faster speed," he says. "And the equipment being installed will allow us to dedicate 10-Mbit/sec pipes to any future applications that need them. We are quadrupling the network`s size, but will run the entire network as Ethernet. If we could have connected all our buildings with a fiber loop, we would have gone with FDDI from day one. But our urban location made this impossible."
He still sees problems with public carriers` data communications offerings. "The telephone companies offer little scalability between T1 and T3 bandwidths," he explains. "We have relatively inexpensive T1 lines now, since the campus is served by one central office. But our costs would increase by 1000% if we went to T3. So fiber is still more scalable. Fiber will also allow us to migrate from Ethernet to so-called Fast Ethernet technology, which will compensate for any short-term bandwidth needs. But five years from now, it will probably be an ATM world, and we will have to address that issue."
Ladd is not shy about pushing suppliers to support his future needs, either. "Nynex`s own copper ran along steam pipes, which gave us continual problems," he says. "They have agreed to replace it with 24-strand fiber." He also told the telephone company he would consider using a Sonet data service only if it were given to him. "And it looks like they may include a non-tariffed, 1.544-Mbit/sec Sonet service when they finish installing the fiber," he adds.
Copper first, then fiber
Several months ago, Robert Gross, director of telecommunications, started installing a new telephone system in the St. Francis Medical Center, Trenton, NJ. "We realized that with nine Netware LANs and 250 PC users on our 10-Mbit/sec Ethernet network, we couldn`t add more to it," he says. "So we decided to upgrade our copper data wiring, too."
When he rewired the campus to Category 5 copper for data and Category 3 copper for voice, he also created a future network-upgrade path with approximately 1500 meters of 12-strand fiber. Multimode fiber was chosen, he says, because it would support more systems and give each system more bandwidth. For example, a future teleradiology application could be given its own dedicated bandwidth. "We plan to test this fiber backbone at speeds to 100 Mbits/sec," Gross says.
The main campus consists of four buildings combined into a single major structure. A separate building houses the library and the nursing school. It is linked to the main complex over underground fiber and Category 5 copper.
3Com, the network vendor, is installing routers and hubs in 13 equipment closets on the fiber backbone network. Each hub will serve three floors of users and will be connected by fiber to the main data center. "We limited each hub to three floors at most, because the Category 5 copper cable has a 100-meter distance limitation," he explains. Fiber loops will also run through building risers to connect hubs on all floors. Gross calls FDDI "the obvious choice" for carrying inter-hub traffic.
But all this fiber is dark. A controlled switchover will take place when the hospital`s information systems staff feels comfortable with the copper network`s stability and the fiber backbone`s readiness. The switchover will not affect hub placement, adds Gross, because copper runs must remain short between hubs and users. "But fiber`s high bandwidth will allow us to consolidate our LAN servers in the secure information systems area, and to run this server traffic to the closets along the backbone," he says. When the time comes, traffic will be moved to the new backbone by switching it between copper and fiber ports in the 3Com hubs.
"We`re exploring other things, too," adds Gross. "We will need to get onto the Internet and engage in more communications with our corporate office and data center in Exton, PA. Networking services such as T1, ATM, frame relay or other wide-area networking services will tap into the backbone and allow us to push bits around this network. We`ll also need fiber`s bandwidth for coming videoconferencing and telemedicine applications."
To prepare for these future bandwidth needs, Gross has also asked New Jersey Bell to replace its copper runs into the medical center with fiber.
Fourfold cost savings
The Big Bear store uses a 1-mile length of multimode fiber to connect its Columbus, OH, divisional headquarters with a warehouse storing non-perishable food products. The 1.4-Mbit/sec link serves 80 Novell Netware users running word processors, spreadsheets and groupware. Business functions performed include shipping, receiving, doing inventory, invoicing and ongoing store-construction projects.
"We own the entire block between our local headquarters and the warehouse," says John Poling, telecommunications analyst. "So it was easy to run the fiber, along with 400 copper pairs for voice traffic." The main reason for using fiber was distance. "We also didn`t have to ground fiber or do special lightning protection," he adds.
The fiber runs between multiplexers in headquarters and the warehouse. Each multiplexer can handle traffic from 128 user devices. In the headquarters building, four cluster controllers manage traffic between the multiplexer and 128 printers and PC terminals. In the warehouse, the multiplexer supports 128 dumb terminals. "The old way of doing this was to use one fiber pair for each 32-port cluster controller," Poling explains. "But the multiplexers compress four controllers onto one fiber pair, for a four-to-one cost savings on fiber."
Across half the span from headquarters to the warehouse, the fiber runs through aerial innerduct. It dives underground for protection when it reaches the company`s trailer yard, then enters the warehouse building and runs across its ceiling.
In the middle of this run, fiber also splits off to the company`s freezer building. "We drop some fiber off there to link our meat office to the Novell network," he says. This link permitted Big Bear to move its meat-office staff from headquarters to the freezer building. "Though they moved further from our computers, they saw improved service over fiber and were finally located where they needed to be--near the meat," Poling says.
The 1-mile link cost approximately $10,000. "We saw a 14- to 18-month return on this investment if you compare it against the alternative--copper-based line drivers. But to do CAD/CAM over copper, you`d need a T1 line for the traffic," Poling adds. "Copper can`t do that. With fiber, we can also move above 20 Mbits/sec when we need to. I won`t say `100 Mbits/sec` because when you try to find someone who is really doing it, you can`t."
If he could do it over, Poling would pull 24 strands instead of 12. "With CAD/CAM traffic on one pair, LAN traffic on another and back-up pairs beside that, capacity goes quickly," he says. In fact, five years into this fiber installation, 10 of the 12 strands are running at capacity. If additional capacity becomes necessary, Poling will probably install a second aerial innerduct next to the first. u
Dave Powell is a freelance writer based in Winchester, MA.