Programmer advances ISDN uses

Communications News, March, 1990 by Kevin Tanzillo

PROGRAMMER ADVANCES ISDN USES

Dory Leifer is making ISDN work at the University of Michigan.

Leifer, a systems research programmer, developed software that lets Integrated Services Digital Network users access campus databases, as well as regional and national resources, from remote locations.

The software, Internet/ISDN Gateway, is one of several ISDN applications being tested at the university. Leifer spent about six months developing it, with the help of Michigan Bell, and now he is improving on it.

The software was demonstrated at the recent Educom conference. In that demo it allowed four workstations and two gateways on personal computers remote acccess to Internet.

"Many colleges and universities rely on Internet Protocol networks to link heterogeneous local area networks to campus backbone networks," explains Leifer.

"To reach across campus, or out to the Internet, a professor, staff usually must first connect to a local area network.

"This is generally expensive if few workstations are involved at a particular location, and it prohibits working from alternative or distant locations, such as at home."

B Channel Options

Internet/ISDN Gateway gives access via ISDN to machines using the Transmission Control Protocol/Internet Protocol. One ISDN B channel connects each workstation to the gateway. The second channel is available for standard voice service.

As an alternative, workstations and gateways can employ both B channels to achieve 128 kb/s.

Throughputs on file transfer have reached 11,000 bytes per second.

"What people would like is the ability to tie their existing research networks with ISDN and extend the capability from just on the campus or on the corporate grounds to off-campus," says Leifer.

"We are looking to expand its scope and make it useful, and employ it in a production environment. What we developed was demonstrated in a very controlled environment."

More robust

"I am working on making it more robust, then looking at scaling," explains Leifer. "We would like to scale it to where several hundred users from the outside could get into it."

Leifer, who says ISDN has intrigued him for several years, has been at the University of Michigan three years. The enhancements to his software are six to nine months from the completion.

That is about the same time frame as the university's expanded use of ISDN (see story on page 18).

As far as the future of ISDN, Leifer is optimistic. "I think when a few of the 'islands' are actually connected and people have larger-scale applications running, I think we'll see almost exponential growth," he says.

"right now it is still on the providing grounds. With incompatibility between equipment and questions about things like tariffs, it is hard to see it moving very quickly.

"But once some of those issues get resolved and we've got some strong customers that have used it successfully, things will really fly."