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By Kelly Jackson Higgins
There's nothing quite like staring at a big, juicy spider, live, in true broadcast quality on a video screen. That's what middle- and high-school students in the Clermont County (Ohio) Public Schools did during a recent research project on insect classification conducted with the Cincinnati Zoo. Soon, the school system will be able to run video sessions with sites outside the county, too, thanks to its new Ethernet and OC-3 ATM-based backbone using MPEG II video compression. The new video network will have a minimum of 10 megabits dedicated for video traffic, another 10 megabits for data and the rest earmarked for future applications, such as stored video and voice over IP. The Southwest Ohio Regional Distance-Learning Network (SWORD Learning Network) spans close to 15 sites in Clermont County, including the school districts and University of Cincinnati-Clermont College and the Cincinnati Zoo in nearby Hamilton County; 10 more sites in Hamilton are scheduled to be added soon.
Broadcast-quality video is the key to any distance-learning application. A typical videoconference can eat up about half a T1 connection on Ohio's state backbone network, for instance, and it's not broadcast quality. It's difficult to reach that kind of quality over a T1, especially if the line also is being used for data, as is the case with the state's network, says Robert Sanders, director of distance education for both the Clermont County Educational Service Center and Hamilton County Educational Service Center. "Using MPEG II compression on the new network, I've seen high-quality video at even 1.5 Mbps, with very little pixelization," reports Sanders.
The SWORD Learning Network replaces Clermont County's DS-3 service, which was tariffed by Cincinnati Bell for video-only. The move to the ATM-based service has saved the school system about $200 per month over its existing DS-3 connection, and it will save even more without the extra data lines that it required. "Depending on what a school district had for data lines, the monthly savings could range from $150 to $700," says Sanders. The key to saving money up front with ATM is avoiding the equipment costs associated with rolling your own private ATM network. The only hardware Clermont had to purchase was an Optivision codec and a Cisco 3600 router for each site--Cincinnati Bell supplied the 3Com 3000 switches, where the ATM service terminates.
But pioneering a broadcast-quality video network also has trade-offs. The next hurdle is finding a gateway to connect the new MPEG II fiber ATM network to the state's T1 ATM network, which uses Vtel equipment and H.321 compression. That way, students and teachers will be able to hold videoconferences with organizations on the state network. Voice traffic will join the network sometime next year, and streaming video is expected to follow eventually.
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