By Bill Steele
In a few years, your computer and your telephone will be joined at the hip. You probably won't notice any difference in performance, but you will have access to a lot of new features, like auto-dialing from an address book and point-and-click conference calling.
Even as it celebrates the 10th anniversary of its conversion to a PBX (Private Branch Exchange) telephone system, Cornell Information Technologies (CIT) is making plans to replace it with an innovative new system that will send phone conversations -- and later, video signals as well -- through computer networks instead of the existing PBX network.
"Cornell needs three first-class networks -- video, voice and data," said Richard Cogger, CIT assistant director for advanced technology and planning. "We're currently paying for two -- voice and data -- and don't have enough money for the third. The only way is to reduce it to one network."
Along with improving service, Cogger said, the new system will save money, or at least keep costs from rising.
"We have about 15,000 lines on our PBX," Cogger explained, "and it grows at 10 percent a year. By the year 2000, we'd have 20,000 lines. It's the biggest switch in Tompkins County." The university's current central telephone switching equipment is almost at capacity, he said, and would cost millions of dollars to replace.
With the new system, computers all over the campus will handle the switching. When you talk on the phone, the sound of your voice will be converted to a string of ones and zeros, in the same way that music is digitized for recording on a CD. Your computer will break the information down into short groups of digits, similar to those that carry e-mail and other computer messages, and send them to the computer on the desktop of the person you're talking to. When that computer receives the data it will convert it back to voice and feed it into the other person's phone handset.
What will make all this possible is a new technology for transmitting computer data called Asynchronous Transfer Mode (ATM) and an innovative way of using ATM on local networks which Cogger has helped to develop, called "Cells in Frames."
Any current generation computer network, from the LAN (Local Area Network) in a small office to the worldwide Internet, sends data in "packets." A packet is just a short stream of data bits with special combinations at the beginning and end that tell computers along the way, called "routers," what the packet is and where it's going. A short e-mail message you send out may be broken into several packets, each traveling on its own, mixed in with lots of other packets being sent by lots of other computers. All the packets in your message may not follow the same route, or arrive at the same time, but the computer at the other end knows how to put them back in order and reconstruct the original message. The sender also keeps a copy of the data until receipt is acknowledged, or, if the acknowledgment doesn't come, sends it again.
That's fine for e-mail, but not so good for voice or video. If parts of a speech are out of order or missing, the result would be unintelligible, and if the receiving computer has to wait for resends, the delay would interfere with normal conversational behavior.
ATM was created by the computer industry to overcome that problem and pave the way for a new generation of "multimedia" computing. It uses very small strings of binary digits, called "cells," that can be switched and moved much faster, and in organized groups. When you connect to someone else's computer for a phone conversation using ATM, the computers will set up a route through all the switches out in cyberspace for your messages to follow, and keep that route open throughout the conversation so the data flows smoothly. This is called a "virtual circuit," because once it's open it works just like the hardwired circuit of the old-fashioned telephone system.
Whatever else happens, Cornell would be upgrading its networks to use ATM, by replacing its routers with new switching hardware. The conventional wisdom has been that every desktop computer would have to be upgraded as well, replacing the Ethernet cards that now connect to network wiring with new ATM cards, at an expense of at least several hundred dollars for each station. Cogger believes he has found a way to bypass that, allowing our computers to use ATM with their existing network Ethernet cards.
To oversimplify, the "Cells In Frames" system will pack a number of ATM cells inside each of the larger chunks of data, called frames, that our current Ethernet cards and wiring use. Some new software will be added to the desktop computer to enable it to decode the data, and a little box, costing about $100, will be tacked on to each phone to connect it to a computer. While we'll need a lot of those little boxes, that still turns out to be vastly cheaper than buying 15,000 new ATM cards, or paying millions of dollars for new PBX switching equipment.
CIT is preparing to launch a test of the new system, with about two hundred stations, funded by a $700,000 grant from the National Science Foundation. Most of that money, Cogger said, goes to a company called Connectware, which is designing a new computer chip that will be the heart of the hardware that packs ATM cells into frames for each Ethernet-connected user.
Once the system is in place it will offer much more than computer telephony, Cogger said. It will, for instance, make it possible for desktop workstations to connect at the high speeds needed to work with supercomputers, without having to make expensive updates to every workstation. A full-motion version of CU-SeeMe, Cornell's popular Internet video conferencing program, is also a possibility.
Cells In Frames is not expected to work for everyone on campus. Some users will need very high speeds (such as 155 Megabits/sec) and be willing to pay their higher costs, Cogger said. But a savings of several hundred dollars each for just 80 percent of Cornell's 15,000 Ethernet connected workstations is still a lot of money, he pointed out. More importantly, he said, it means getting the benefits of ATM several years sooner for large numbers of campus network users.
The focus right now is on the telephone system, just because "That's where the money is," Cogger admits. "Those of us in the computer network business have had this vision of a single high-speed network that provides everything, but spending on multimedia networks is zero," he said.
How soon will all this happen?
"I gave Scott Brim and Dick Cogger a target of 1998," said H. David Lambert, vice president for information technologies. "That was an aggressive schedule. We have to influence vendors and create some technology that doesn't exist." Brim, a senior technical advisor with CIT, has primary technical responsibility for the new project.
Cogger expects field trials to last through this year, with deployment of a real system starting in 1997.
"How long deployment will take is not clear," he said. "Certainly less than three years. Our ambition is in the year 2000 to have shrunk to 12,000 phone lines on the PBX and be on the way down."
Detailed information on Cells in Frames is available at http://cif.cornell.edu/ on the World Wide Web.