Network users wrestle with ATM option

Unlike most technologies Asynchronous Transfer Mode (ATM) networking has been one that the federal government adopted earlier than most commercial users. Today one can scarcely point to any federal agency that has not at least experimented with the technology. For years ATM vendors have trumpeted the technology's ability to merge voice video and data while taking advantage of transmission speeds as high as 622 megabits/sec.

All of this can translate into savings for users according to vendors. Brian McMahon ATM product line manager at Bell Atlantic Federal Systems said his company offers a commercial ATM service at 155 megabits/sec for $1 975 a month while it charges $950 per month for 10-megabit Ethernet service. "The higher the bandwidth the cheaper the megabit " McMahon said.

"ATM is the cheapest technology per megabit by far." Certainly the comparison looks good on paper. But some vendors and federal users have begun questioning whether the government has moved too quickly into the realm of ATM. Users remain unsure as to how to address security and network management issues on ATM networks. Their lofty plans to bring ATM connections to the desktop have not proved cost-effective. And few agencies have yet been able to take advantage of the multimedia capabilities offered by the technology.

"There was a point in time where people thought ATM was a panacea to be used everywhere " said Scott Marcus director of systems architecture at GTE's Global Network Infrastructure business unit. "Mostly that notion has not panned out. ATM has not dominated the local space and most analysts don't expect it to dominate [rival technology] Gigabit Ethernet."

ATM Promise Certainly ATM shows a lot of promise. Essentially it speeds transmission and improves service quality by breaking down network traffic into small fixed-size cells of 53 bytes. This improves upon the Ethernet model in which data frames can range from 64 to 1 518 bytes. That can create problems if an essential piece of information contained in a small data frame is blocked by less important information contained in a larger frame.

For that reason most users do not consider Ethernet a reliable technology for delivering voice or video which have strong requirements for the stable delivery of information. ATM's fixed cells on the other hand merge data voice and video traffic and prioritize traffic that is more sensitive to latency. Despite its promise to accommodate multimedia applications most ATM users so far have focused on data and are using the technology to interconnect local- and metropolitan-area networks. This has led some observers to question whether these users really needed an ATM solution.

"At this point in time I don't think there is any vendor who would dispute the use of ATM on connecting campus-style environments through wide-area networks that's going to be the common denominator in the wide area " said Robert Travis program director for federal government business at Cabletron Systems Inc. "Now the question is do you have to run ATM in the campus-level environment? Not if you're just supporting data."

Jim Masa director of federal operations at Cisco Systems Inc. said his company - although best known for routers - has successfully migrated into the ATM market and has won federal contracts - including one awarded last month by the Federal Reserve Board - to install the networks at federal agencies. Despite Cisco's success in the ATM market Masa continues to question the judgment of some users who have embraced ATM without an apparent need for it.

"I've seen many organizations use ATM for data only " Masa said. "When I see that it raises some questions as to why they are using ATM as opposed to some other high-speed technology. The federal government is much more excited about ATM than almost any commercial sector."

Richard Bibb vice president of federal operations at Fore Systems Inc. said federal agencies have installed ATM early because it offers a migration path that can accommodate future multimedia and high-bandwidth applications as they are fielded. He said some users especially those working in Defense command and control applications need ATM's ability to deliver high-quality multimedia to the desktop. In addition agencies have been using ATM as a means to save money by consolidating networks he said. "The dollars are getting more scarce " Bibb noted.

"And when agencies are going to make a major infrastructure decision they can't go back to Congress the next year and say they didn't get it right." Long-Term Investments Federal officials who have begun installing ATM networks running only data say they plan to run video and eventually voice over ATM in the future. Many view their plunges into ATM as long-term investments.Brian Carman acting director of corporate systems management at the Treasury Department said the Internal Revenue Service and the Customs Service have installed Bay Networks Inc.

Centillion 100 ATM switches at its new facilities and computer centers. He noted that nearly all of the department's ATM traffic is data and that ATM was selected to accommodate the network's growth. "We have a very large growth rate in data traffic " Carman said. "We need a technology that will support high data rates. ATM is fairly scalable so we can expand the community we are going to deal with and support it. "There is a desire to look at merging traditionally separate media to a single solution to the desktop " he added. "Videoconferencing is the next step and ATM holds a lot of attraction for us in that area. I'm not aware of any other technologies that offer that capability."

Despite their endorsement of ATM Treasury official do have their reservations. Anderson said he has had difficulty addressing the issue of data encryption because of the lack of commercial products that can encrypt data traveling at ATM speeds of 45 megabits/sec or more. He said he also has concerns about how he can centrally manage ATM devices provided by different vendors.

Although the industry is standardizing on the Simple Network Management Protocol "ATM vendors' devices have some specific anomalies " he said "so we can't manage everything centrally." ATM advocates in DOD believe these problems can be addressed. Hank Dardy chief scientist at the Naval Research Laboratory said GTE has developed an ATM encryption device that has worked successfully within DOD and has been approved by the National Security Agency.

And although the lab has been grappling with the management issue Dardy said he believes the ATM Forum which is the industry group that develops standards for ATM products and services will address the issue imminently. Dardy said the technology has worked well for distributed computing applications and desktop applications such as high-performance visualization.

"ATM is being used completely across our infrastructure now " Dardy said. "We are running it for high-performance computing to the desktop at OC-3 [155 megabits/sec] and at OC-12 [622 megabits/sec] to the server."

Considering Alternatives On the other end of the spectrum officials at the Environmental Protection Agency said they have not yet encountered an instance in which ATM makes business sense.

Bruce Almich the EPA's technical manager of data telecommunications said he sees no future for ATM to the desktop adding that he believes Gigabit Ethernet will become the technology of choice for backbone networks. But he also said the EPA is "looking for opportunities" to exploit ATM's capabilities at the WAN and campuswide network levels. Almich said the agency had been looking at ATM about three months ago as a way to connect users in Raleigh N.C. to the agency's supercomputer center in Bay City Mich. But he found that line-access charges through the General Services Administration's FTS 2000 telecom contract would have been excessively high. "It just didn't make sense " Almich said.

A previous EPA experiment with ATM in a workgroup setting showed that the technology offered no improvements over the existing Fiber Distributed Data Interface architecture Almich added. "The industry trend says that ATM has lost the desktop and we don't see any immediate business case that would lead us to jump the track on that " he said. "But we are still open to discussion on the WAN and campus environments. We haven't closed the books yet."

Critics argue that other technologies such as Gigabit Ethernet are beginning to appear that may eventually eclipse ATM for requirements such as those at the EPA. GTE's Marcus said his company has tested a technology known as packet-over-Sonet in which traditional routers are souped up to drive high-speed traffic without what he called "the ATM cell tax " which is a hit that ATM users take because up to 10 percent of the 53-byte ATM cell can be composed of "overhead" such as cell header data. Dardy disagreed asserting that ATM has proven extremely cost-effective within DOD.

And he strongly added that DOD simply does not believe in Gigabit Ethernet. "We have to provide a global infrastructure - something that works across a room but also works across a city " he said. "I don't see that capable of happening with Gigabit Ethernet." No Consensus Even ATM's staunchest critics agree that the technology has a place but finding consensus as to what that place might be can be difficult. Despite the differences of opinion many agencies have decided to push forward even if the commercial world has not.

And some observers think that push in itself may be enough to boost ATM to the forefront of networking technologies. "I think that when it is all said and done the government has been a good leading indicator of the direction of the communications industry for a long time " said Fore's Bibb.

* * * * * At A Glance

Status: ATM has not caught on as quickly as the industry expected particularly below the wide-area or campuswide network level.

Issues: Some users are concerned about addressing issues such as network management and data encryption in ATM networks. Also few agencies appear poised to take advantage of ATM's ability to handle multimedia data formats.

Outlook: Uncertain. Some agencies view ATM as the long-term solution but Gigabit Ethernet and other technology are attractive alternatives.


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