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 U.S. 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 Inc.'s 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.

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