AF group says bye to FDDI

AF group says bye to FDDI

Eyeing a network, service says fiber simplifies long runs from wiring closet

By William Jackson

GCN Staff

The Air Force's Materials and Manufacturing Directorate has raised its sights for a campus network at Wright-Patterson Air Force Base, Ohio.

Gigabit Ethernet is replacing the campus' 100-Mbps Fiber Distributed Data Interface backbone, and Thinnet Ethernet LANs are giving way to switched 10/100-Mbps Ethernet over fiber to desktop PC systems.

'We decided to skip twisted-pair and go directly to fiber,'' said Bryon Foster, senior network manager for the directorate, part of the Air Force Research Laboratory.

Fiber simplifies long runs from the wiring closet that exceed the limits for Category 5 twisted-pair copper, he said, and fiber is more secure than copper. Using VF-45 optical connectors in the Volition cabling system from 3M Co., the cost of running fiber is only slightly more than for copper, Foster said.

The Air Force Materials and Manufacturing Directorate simplified long cabling runs in its Gigabit Ethernet campus upgrade by using the Volition fiber cabling system.

A VF-45 optical connector has a plastic connector and looks and works like a standard RJ-45 telephone jack.

'We're fairly early into it,'' he said. Only three of 20 floors in five buildings have been cabled, and work progresses as funding becomes available.

Category 5 wiring is marginally cheaper than fiber by about 15 percent, but the prices are close enough that bandwidth, security and future-proofing can tip the scale in fiber's favor, according to Vincent Wong, president of Gemflex Networks Ltd. of Richmond, British Columbia.

That is what happened at Wright-Patterson, where the Materials and Manufacturing Directorate was outgrowing its 1,300-node FDDI Thinnet.

'People weren't supporting it, and we were looking for higher bandwidth,'' Foster said.

Filing along

The directorate's researchers work in graphics-intensive applications that produce 100M and larger files. In molecular modeling, for instance, the models might have to be rotated and displayed across the network. 'Dedicated 10 Mbps between two points wasn't enough to do interactive applications,'' Foster said. 'You have to have 100 Mbps.''

Furthermore, the 10 Mbps usually was shared among five or six machines. 'That wasn't terrible,'' Foster said, and some machines did have a dedicated 10 Mbps. A few even had FDDI to the desktop. But the volumes of data were beginning to overwhelm the 100-Mbps backbone. 'We started hitting the wall on day-to-day operations,'' he said.

Installation of 13,000 feet of 24-strand multimode fiber began last year to replace the backbone. One floor has been wired with 13,000 feet of four-strand fiber. Work is progressing slowly on the other floors. There is no timetable for completing the project, which Foster estimated could take until 2001 or 2002.

As soon as cabling is done on each floor, it is cut over to the new backbone. For the time being, a gateway connects it to the old FDDI backbone, which has 2500 and 6000 series switches from 3Com Corp. of Santa Clara, Calif. Foster said new hardware for the Gigabit Ethernet backbone and switched Ethernet LANs will be bought when enough floors are finished to justify a purchase.

The directorate is leaning toward backbone switches from Cisco Systems Inc. of San Jose, Calif., he said. Initially, each floor will have a 10-Mbps switch, and each floor switch will connect by a 100-Mbps uplink to a Fast Ethernet switch in each building. The floor switches probably will come from 3Com, and the 100-Mbps and faster switches from Cisco, Foster said.

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