Base updates its training LAN

The Training and Education Center at McGhee-Tyson Air National Guard Base in Knoxville,
Tenn., is a fairly new facility with an up-to-date fiber backbone. But by 1997, its
distributed learning network had become woefully inadequate.


A shared Ethernet ran the Vines network operating system from Banyan Systems Inc. of
Westborough, Mass., connecting desktop 486 PCs with 8M of RAM each.


“It was pretty bad,” said Master Sgt. Robert Lowman, the communications
manager.


The 180 PCs that provided e-mail and word processing to the dormitory rooms were
essentially dumb terminals that booted from floppy disks.


Because administrators did not have time to visit each PC, “all applications ran
off the server,” Lowman said. “There was a lot of LAN traffic. Throughput was
terrible.”


Lowman and the LAN administrator, Technical Sgt. Pete Hennessey, put together a plan to
upgrade the old network to asynchronous transfer mode.


“I phased it in a five-year plan,” Lowman said. ATM would go on the backbone
first to relieve the pressure, and the rest of the network would be upgraded in small
groups.


Then, Lowman said, “I guess they found a different source of money,” and the
entire project was to be done at once.


“That was a blessing and a nightmare,” said Hennessey, who with Lowman
installed the new equipment while maintaining the network.


Excited about the project at first, Lowman said, he began to realize that telescoping a
five-year plan into a single job left no time to eradicate bugs.


The upgrade began in July 1997. Not everything worked right at the start, but a year
later, ATM is carrying video on demand to more than 300 desktops over a network of hubs
and switches from Bay Networks Inc. of Santa Clara, Calif.


“The network smokes,” Lowman said. “Response time is
instantaneous.”


The Knoxville campus provides training for the entire Air National Guard. Each year it
hosts the Non-Commissioned Officer Academy and the Academy of Military Science officer
training course—each six weeks long—as well as 55 weeks of shorter courses.


Until this year, computers in 180 dorm rooms were used mostly for writing assignments
and e-mail. A new dorm with 75 computer-equipped rooms opens this year.


Lowman and Hennessey considered Fast Ethernet for the network upgrade. It was
inexpensive and would be a relatively simple upgrade from the existing Ethernet. But it
did not have the multimedia capabilities necessary for video, which was one objective.


ATM also was attractive because, although most buildings on the campus had Category 5
wiring, a few had Category 3, Hennessey said. ATM could work over Category 3, whereas Fast
Ethernet would have required running new cable in the buildings.


The new network’s OC-3 fiber backbone uses the base’s infrastructure. Servers
run Microsoft Windows NT, desktop systems run Windows 95.


At the center is a Bay 5000 backbone hub. Centillion 100 switches connect to Multimedia
Workgroup Switches for the video applications and desktop connections. The 200-MHz Pentium
and Pentium II desktop stations are equipped with 25-Mbps ATM network interface cards.


The center broadcasts video via the V-Caster from First Virtual Corp. of Santa Clara,
Calif. Video on demand is provided by the First Virtual’s V-Cache, which stores 100
hours’ worth on a large disk array. Students are able to access course material in
their rooms.


The primary lessons the two men learned from upgrading a major network so rapidly were
to plan and train, and then plan and train some more, Lowman said.


Training is key in moving from Ethernet to ATM, he said, and should come well in
advance of the installation. “That’s something we didn’t do. We trained as
we went,” Lowman said. “If there had been training up front, it would have been
better.”  

About the Author

William Jackson is a Maryland-based freelance writer.

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