New switch products from GDC, Fore improve ATM bandwidth

Asynchronous Transfer Mode technology, still viewed as the preferred future networking technology by most agencies, continues to move forward with announcements by General DataComm Inc. of an upgrade to its voice-over-ATM technology and by Fore Systems Inc. of a new high-bandwidth switch.

GDC officials expected today to unveil an upgraded Voice Service Module (VSM) for their GDC Apex switch that will allow users to put compressed voice traffic over ATM networks over as many as 120 channels. Bob Bauer, vice president for marketing at GDC, said a fully loaded VSM would bring the cost of voice-over-ATM down to $250 per channel.

Fore's new switch, the ASX-4000, will offer 40 gigabits/sec throughput, which is four times the capacity of the company's current ASX-1000 switch. Richard Bibb, vice president for operations at Fore Federal Systems, said last week the company has just begun shipping beta versions of the new switch.

Consultant Frank Dzubeck, president of Communications Network Architects, Washington, D.C., said the announcements illustrate the continued need for ATM among users who want to combine voice, video and data. "If you want to manage your bandwidth dynamically but also have service-level guarantees, right now ATM is the only thing that does that," Dzubeck said.

Bauer said GDC's new VSM upgrade improves the company's previous offering by decreasing the amount of bandwidth needed for running voice-over- ATM. It also provides a scenario in which users no longer have to "carve out" bandwidth for voice traffic, he said.

The module allows a user to choose between two compression algorithms, depending on bandwidth requirements. "You can mix voice and data traffic," Bauer said. "And the user can determine the quality level that suits his needs."

Dzubeck said he believes most users will not opt to run native voice-over-ATM when it is likely to become more efficient for them to "packetize" voice traffic and send it out over their Internet Protocol networks. "If I packetize voice, I could have it going along for the ride along with my data traffic over IP," he said. But he acknowledged that voice-over-IP will probably not be competitive with voice-over-ATM for another five years.

Rich Stankevich, product marketing manager at GDC's ATM unit, said users at that time may choose to run voice-over-IP applications over their ATM networks. "I don't see these technologies as exclusive of one another," he said.

Bibb said the company's new ASX-4000, with switching capacity of up to 40 gigabits, supports up to 16 OC-48 connections at 2.5 gigabits/sec or 64 OC-12 connections at 622 megabits/sec. He said the switch is aimed at campus backbone networks to connect other ATM switches, desktops or local-area networks.

"With [World Wide] Web-based applications, bandwidth requirements for just IP traffic is growing at a tremendous rate. And ATM is emerging as the technology of choice because it can scale to these kinds of speeds," Bibb said.