Gigabit Ethernet quenches Army's bandwidth thirst

The Army site's "need for a backbone that won't affect other traffic is
growing," said Steve Lewis, a former network design engineer with Dyncorp of Reston,
Va., which runs the Aberdeen network. "Gigabit, from what we've seen so far, is going
to work well."

At the headquarters building, Dyncorp has installed two Gigabit Ethernet switches with
eight ports each from NBase Communications of Chatsworth, Calif., on the base's Fiber
Distributed Data Interface network, Lewis said. Now that the headquarters staff has
adapted, Aberdeen is ready to add more hubs, he said.

The move to Gigabit Ethernet is a tenfold leap from the 100-megabit/sec speed achieved
over the network's current switched FDDI architecture.

Both asynchronous transfer mode and Integrated Services Digital Network have their
places, said Aberdeen's chief information officer, John B. Ruhl. "But why not migrate
once," he said. "100 megabits is a nice bandwidth, but with what we wanted to
do, it wasn't going to be enough."

What the scientists at Aberdeen wanted to do was use more real-time video for data
acquisition and move larger amounts of data quickly over the network to more users.

The proving ground is one of a handful of Defense Department test centers and is a
repository for test data on all military equipment.

"Test cycles are drawing closer," Lewis said.

And as tests become more complex, evaluators want more data in real time.

In addition to data gathering, evaluators wanted to do more videoconferencing. All of
this was a challenge for the 10-year-old fiber-optic network with 3,000 devices serving
1,000 users and more than a dozen test ranges.

"That can be done right now with existing technology, but if you get a lot of
people using that, it's going to slow the network down," Ruhl said.

Ruhl and Lewis saw the future of networking in Gigabit Ethernet and took a calculated
risk, agreeing to take the first of the fast switches that NBase produced.

"We made arrangements to be the first ones," Lewis said. "We also made
the first offer to 3Com Corp. and Cabletron Systems Inc." But NBase was the first
company to come through with the hardware.

The Institute of Electrical and Electronics Engineers does not expect to vote on
standards for the technology, which transmits at 1 gigabit/sec over fiber-optic cable,
until July. But the folks at Aberdeen were impatient. This was right in character for the
Army facility that ordered the construction of the world's first electronic computer more
than 50 years ago.

The Army wasn't going to wait for a product; it was going to emerge with it, Lewis
said. "If it burps, we'll burp with it."

The risks were mitigated by the fact that both NBase and Cabletron agreed to upgrade
their switches free of charge if needed to meet IEEE 802.3z standards when they are
published. Besides, the industry has recognized the need for a common solution to gigabit
transmission, Ruhl said.

"I think it's very low risk," he said. "It's not like we have a VHS
machine and we're trying to put a Beta cartridge into it. We've moved video over it, audio
over it, and everything has worked."

The proving ground has used videoconferencing equipment from PictureTel Corp. of
Danvers, Mass., to test the high-speed links because there is no test equipment for
Gigabit Ethernet yet, Lewis said.

Video and audio signals give evaluators an easy way to see and hear how the network is

Gigabit switches eventually will replace all of the MMac-Plus LAN switches from
Cabletron now being used at Aberdeen.

"I don't have the money to go right out and upgrade everything," Ruhl said.
"Our plan is over the next year or two to upgrade the real high-volume users."

It will likely be four years before the entire network upgrade is complete, he said.

About the Author

William Jackson is a Maryland-based freelance writer.

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