Building bigger pipes
- By Cheryl Gerber
- Aug 28, 2000
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
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
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
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,"
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.