Building bigger pipes

It sounds almost too good to be true. Bandwidth-hungry agencies that have

upgraded their networks with Gigabit Ethernet on IP-based backbones rather

than Asynchronous Transfer Mode (ATM) are saving themselves both headaches

and money. Besides the obvious bandwidth boost, network managers can expect

a variety of benefits by adding Gigabit Ethernet switches to their network

backbones. And if they handle the design and installation details properly,

they can expect a smooth upgrade as well.

Agencies are eager to keep their networks up to speed with new data- intensive

applications such as video conferencing and distance learning. Many of those

familiar with Gigabit Ethernet on IP and ATM have a clear favorite.

"You get ease of manageability and ease of use with Gigabit Ethernet,"

said Wilford Parker, network manager for the Army Joint Readiness Training

Center at Fort Polk, La. "It's just easier to understand and to work with

than ATM."

The Army upgraded its network at Fort Polk because its existing ATM

backbone was being taxed by a new crop of bandwidth-greedy applications.

Using Foundry Networks' BigIron 8000 switches in the backbone — what

the Army base refers to as the Main Communications Node — and BigIron 4000

switches in its Area Distribution Nodes, Parker achieved a fast, cost-effective

upgrade. He pulled out $1 million worth of ATM equipment and replaced it

with Gigabit Ethernet in less than two days.

By installing Gigabit Ethernet switches on the Army's existing IP-based

backbone, Parker increased his switching speed from 155 megabits/sec on

the former OC-3 ATM network to 1,000 megabits/sec (1 gigabit) for one-third

what it would have cost on the ATM network.

Because Ethernet uses IP addressing, the center didn't have to contend

with any addressing conversion issues as it would have with ATM. And because

Parker used only Foundry Gigabit Ethernet switches, he hasn't encountered

multivendor interoperability problems — yet. "My first taste of that will

come soon when I tie the Foundry switches to Cisco [Systems Inc.] Gigabit

Ethernet switches for support of the Army distance learning program," he

said.

But Parker won't be taken by surprise. "You can never expect not to

have any interoperability problem. It's hard to test every connection there

is in this fast-moving world. Any time you make a code change in one switch,

it can affect your interoperability between switches."

Product interoperability, enforcing traffic priorities and ensuring

consistent quality of service are leading issues with Gigabit Ethernet switching

today, partly because the technology's promise doesn't always fit with reality

and partly because of the inevitable multivendor environments.

"Some of the hype is that vendors can provide quality of service end-to-end,

but that's only true when it's one vendor's equipment," said Eric Thompson,

senior analyst for enterprise networking at Gartner Group Inc. "All switches

can pass an Ethernet packet, but they can't all handle the priorities the

same."

Vendors acknowledge that consistent quality of service and multivendor

interoperability are works in progress. "Even though Gigabit Ethernet standards

are complete, we still see challenges in vendor-to-vendor interoperability,"

said Ken Albanese, senior systems engineering manager for Cisco Federal

Operations in Herndon, Va. "Interpretation of standards can be different

from vendor to vendor."

One example is trunking — the ability of switches to handle multiple

local-area network segments under one port. "That standard has been misinterpreted,

so you'll see more challenges with trunking in a multivendor environment,"

Albanese said.

In one respect, Gigabit Ethernet vendors consider multivendor interoperability

a good problem to have. "The issue is not so much a result of Gigabit Ethernet

but of growing the scalable Ethernet market from 10 megabit to 1,000 megabit

and 10,000 megabit," said George Prodan, vice president of marketing for

Extreme Networks Inc., Santa Clara, Calif.

To avoid interoperability issues, some network managers choose to stick

with one vendor's switches, at least for now. "We've put only Cisco switches — Catalyst 6000 and 4000 — on both ends," said Scott Morrison, network manager

for the Air Force's All Service Combat Identification and Evaluation Team

at Eglin Air Force Base, Fort Walton Beach, Fla.

Some users go so far as to specify a lot number when ordering components

and benchmark their ability to work together before deploying them. "We

use a single vendor for all components within a given cluster to the point

of trying to get a single manufacturer's lot number of all those components,"

said Stephen Scott, research scientist for the Energy Department's Oak

Ridge National Laboratory in Oak Ridge, Tenn.

Scott uses Foundry Networks' BigIron 8000 Gigabit Ethernet switches

with Syskonnect Inc.'s Gigabit Ethernet network interface cards (NICs).

Before he chose that combination, he benchmarked the components to see how

they worked together. "The Syskonnect cards beat the other cards," he said.

Gigabit Ethernet switches and NICs are available for both fiber and

copper cable. Gigabit Ethernet on copper has a distance limitation. However,

that isn't a problem with fiber cable. Because Morrison is building a network

backbone for the future — a pipe that can handle voice, video and data on

one line — he upgraded on fiber.

Both the Gigabit Ethernet and NIC markets have grown rapidly. Four-year-old

Extreme Networks has grown its Gigabit Ethernet switch business to revenues

of $262 million this year. "The Sys-konnect Gigabit Ethernet NIC business

has increased 40 percent from quar-ter to quarter since the beginning of

the year," said Jim Kuciel, chief operating officer for Sys-konnect, San

Jose, Calif. "We're selling every one we build, and we're just able to keep

up with demand."

Gigabit Ethernet is not stopping at LANs or at mere gigabit speeds.

As application bandwidth hogs such as voice over IP and video training continue

to grow, so will the need for increased bandwidth.

Dan Bradford, director of the Army's Technology Integration Center,

Fort Hua-chuca, Ariz., predicted: "In the [wide-area network], ATM is popular,

but 10 Gigabit Ethernet will challenge it beginning next year."

—Gerber is a freelance writer based in Kingston, N.Y.