InformationWeek

November 17, 1997

LANs: ATM Bounces Back

Ethernet is still king of the LAN, but more users are looking to ATM for greater flexibility and reliability

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here's no question that faster strains of Ethernet are the technology of choice for boosting LAN bandwidth. But asynchronous transfer mode-alternately declared the future and decried as the flop of local area networking since it emerged from the standards bodies in the 1980s-is making headway among companies seeking the reliability and flexibility Ethernet still can't provide.

Numbers released last week by the Dell'Oro Group show a market in motion. Shipments of ATM LAN equipment, after stumbling earlier in the year, grew a healthy 8% in the third quarter compared with the previous quarter, and were up 73% from the third quarter a year ago. Growth in manufacturer revenue is als o healthy, despite price cuts on ATM backbone switches, workgroup switches, and network interface cards.

"There's a fallacy out there that ATM in the LAN is tanking," says Tam Dell'Oro, founder of the group. "Vendors keep reporting quarter-over-quarter growth, and some of them show quite significant growth."

Why the renewed interest? For one thing, vendors are delivering ATM products that are not only cheaper, but are also easier to install and will support Ethernet connections.

At Comdex/Fall 97 this week, 3Com Corp. will introduce the CoreBuilder 9000, a high-end LAN switch that will support either ATM or Ethernet technology and scale to 88 Gbps on the backplane. Bay Networks Inc. next month will unveil an ATM road map that includes plans to ship new switching modules and to support standards that ease routing between ATM switches. Madge Networks Inc. next month will unveil a Layer 3 switch that supports routing as well as cell and frame switching.

Sources say market leader Cisco Systems Inc. is planning a high-end platform, the Catalyst 10000, that supports both ATM and Ethernet. Fujitsu and Samsung last week separately announced plans to enter the U.S. ATM LAN switching market. Products that allow migration to ATM also continue to roll out. Connectronix in Salt Lake City last week introduced the AFB series of switches, which let companies using 100-Mbps Fiber Distributed Data Interface-still the dom- inant LAN backbone technology-migrate more easily to ATM.

While ATM all the way to the desktop is still rare, an increasing number of companies are banking on the cell-switching technology to aggregate connections to buildings and workgroups. Fat pipes are one thing, and the 622-Mbps flavor of ATM stacks up well against Gigabit Ethernet. But the elegance of ATM is in its quality-of-service guarantees and support for multiple traffic types.

Commercial Financial Services (CFS) in Tulsa, Okla., is implementing faster LAN technology to keep up with hypergrowth. The company chose ATM over hi gh-speed Ethernet "because it gives us a great deal of inherent flexibility in handling our traffic," says CIO Chris Horrocks. "Our traffic peaks and troughs very strangely. Any other solution would have caused us to overkill bandwidth quite dramatically."

CFS, which specializes in collecting and repackaging credit-card debt into securities, has grown from 350 employees in January to more than 3,000. To accommodate that expansion, the company spread its credit system, previously on a single Novell NetWare server, across five NetWare servers housed in Tulsa and Oklahoma City. This month, CFS expects to complete a migration from Bay LatticeSwitch Fast Ethernet switches that run the two LANs to Bay's System 5000 and Centillion 100 multitechnology switches. The company has already replaced four T1 WAN links with a single 155-Mbps ATM connection.

Ready For The Future
Other companies are looking to ATM to future-proof their networks in anticipation of multimedia applications that run across WANs and LANs. ATM provides inherent bandwidth and data-delivery guarantees, known as quality of service (QOS), for these applications. To implement QOS end-to-end would require running ATM to the desktop. Instead, some companies are running ATM at least to workgroup switches and then simply overprovisioning bandwidth to the desktop.

McGuire, Woods, Battle & Boothe, a law firm in Richmond, Va., is implementing a LAN for about 1,100 users, with Fore Systems ES-3810 workgroup switches providing ATM on the backplane and switched Ethernet to the desktop. "We were looking for high bandwidth with the potential to do QOS," says Jim Dobrzeniecki, the company's CIO. "We are going to be implementing video applications-among other things, videoconferencing-first for internal training and then possibly extending out to our clients. Video will be a big part of our network in terms of service delivery."

ATM is also taking root among large IBM shops that use token ring instead of Ethernet. Cincinnati Financial Corp. , a large Midwest insurer, has just begun deploying the 3Com CoreBuilder 7000 and 2000 ATM platforms to support its network of about 1,800 users.

"Even though we don't need the extra bandwidth today, I wanted to have it in place so that we could be proactive as applications come down that need the bandwidth," says Tim Brockman, a network analyst with Cincinnati Financial. "We felt we didn't need to throw away our token-ring infrastructure just to bring in Ethernet. With ATM, we have better performance, but the desktops can still be on token ring." The company has updated its IBM mainframe to handle a 155-Mbps ATM link.

Even after aggressive price cuts, 155-Mbps ATM is still more expensive than 100-Mbps Fast Ethernet, and 622-Mbps ATM is pricier than 1-Gbps Gigabit Ethernet. For instance, a 622-Mbps connection-consisting of switch port and NIC-from Fore Systems fetches $6,000, compared with $3,900 for a Gigabit Ethernet connection. But the gaps are closing. Fore is said to be readying its annual round of price cuts of 20% to 40% on switches and NICs.

For Virginia Power, a utility in Richmond, the cost differential wasn't so high, says senior engineer Tom Rega. "We looked at one vendor's Ethernet solution, with FDDI to provide resiliency, and we found that the cost of Fore's ATM technology was quite competitive," he says.

At the utility's headquarters, several Fore ASX-1000 high-end switches function as the core of the LAN. Two are connected by redundant 622-Mbps links, and the rest by 155-Mbps links. Two connect to the ES-3810 workgroup switches, which provide 10/100 Mbps Ethernet connections to the desktop, and two other ASX-1000s run 155-Mbps connections to the servers.

The potential to combine voice and data traffic was a key in the utility's decision to go with ATM. "We may want to combine our phone and data traffic on the WAN," Rega says. "ATM provides us with a common infrastructure, blurring the lines between the LAN and the WAN."

Dave Passmore, a principal of Decisys Inc., a co nsulting firm in Sterling, Va., thinks the recent establishment-after years of delay-of the Multiprotocol Over ATM standard will boost the market. "It's a nice way to do routing across an ATM backbone that's interoperable and scales well," Passmore says.

Still, nobody is predicting that ATM will outstrip Ethernet in the LAN. Ethernet dominates the world's LANs, and the easiest, lowest-cost upgrade is to a faster form of that technology.

The Miami Herald is using Gigabit Ethernet switches from Foundry Networks in one part of its network, upgrading from Fast Ethernet, to supply more bandwidth to the staff responsible for producing graphics for the newspaper.

"Our graphics are getting bigger-we have files of up to half a gigabyte going across the network-and performance was going down," says network administrator Brian McNabs. "ATM has a lot of good features, but it cost more-especially 622-Mbps ATM-and in our case, it wouldn't have bought us anything more."

That may well be true for many networ king users. But as lots of large companies are discovering, the time to catch the ATM wave may be when the hype has peaked, crashed, and receded-leaving time in which to test the technology on its merits.

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