Gigabit Ethernet vs. ATM: Which one will survive?

BOSTON—Ethernet’s inventor does not believe in peaceful coexistence, at least
not among networking superpowers.

“I think asynchronous transfer mode and Gigabit Ethernet are going to fight it
out,” Robert M. Metcalfe said this month at the Gignet conference.

Metcalfe said he’s putting his money on Gigabit Ethernet. He declared the ATM to
the desktop campaign dead, adding that ATM is nearly dead on the LAN backbone and under
attack on the WAN.

But many ATM vendors at the conference predicted that the two networking superpowers
will be forced to work together in mixed environments for the foreseeable future.

“ATM will continue to be deployed on the wide area,” said P.G.K. Menon,
marketing director for Cabletron Systems Inc. of Rochester, N.H.

Even early adopters in the federal government are reconsidering end-to-end ATM in favor
of Gigabit Ethernet, Menon said.

“We expect the government to buy quite a few Gigabit Ethernet switches and
routers,” he said.

Ethernet, which was introduced commercially in 1982, is ubiquitous on LANs running at
10 Mbps.

Fast Ethernet, meanwhile, has quickly pulled ahead of Fiber Distributed Data Interface;
both can deliver up to 100 Mbps over unshielded twisted-pair cable.

One conference speaker noted that such contests are not always decided on technical

“There are no technical reasons why FDDI is being phased out. It’s a good
backbone,” said Alan Brind, marketing vice president for Performance Technologies
Inc. of Rochester, N.Y. “Ethernet isn’t resilient. FDDI is resilient.”

FDDI has lost its market share because upgrades and maintenance are difficult, Brind
said. It has not disappeared, however, especially on government networks.

And not even Metcalfe suggested that ATM will vanish in either the government or the
commercial sector.

Agencies “are buying ATM for the same reasons everybody else is,” Metcalfe

“ATM will persist as long as IP is one of many network services,” he said,
because its central strength is its ability to integrate services.

Metcalfe did not always consider Ethernet superior to ATM. Five years ago, he had
predicted that ATM’s quality-of-service guarantees would make it prevail. But he said
ATM has not delivered on its promise and, in the meantime, Gigabit Ethernet is threatening
to catch up through Layer 4 switching.

“You can do more with a packet in a connectionless system than you could
before,” Menon said. “All you do is look a little deeper into the packet to
determine the session and maintain it.”

Layer 3 and 4 switches that guarantee service quality for packet switching are now
being tested, Menon said. “I expect large-scale deployment to happen later this year
or early next year,” he said.

That’s when the final round could begin in what Metcalfe called a fight to the

About the Author

William Jackson is a Maryland-based freelance writer.


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