ADSL and Terminal Server Add Life to Old Machines
Eye On: Kidz Online
Most schools are not blessed with the latest and greatest technology. Instead, many students work on old 286- and 386-based PCs. Using Microsoft Corp.’s Windows NT Terminal Server, Citrix Systems Inc.’s Independent Computing Architecture (ICA) protocol, and asymmetric digital subscriber line (ADSL) technology, Kidz Online (Falls Church, Va., www.kidzonline.org) has found a way for schools and companies alike to make the most out of machines that would otherwise be headed for the junk heap.
Kidz Online makes a CD-ROM library that is accessible either by a dial-up connection or via the Internet. Within the Kidz Online library are audio- and video-intensive educational applications. Here’s where the combination of Terminal Server, ICA and ADSL comes into the picture. Students are given access, via a login name and password, to a Kidz Online server running Windows NT Server 4.0 Terminal Server Edition. Terminal Server enables multiple users to access applications running on NT servers. Users can log onto the server from a variety of locations and a variety of machines.
Through Terminal Server, users have access to the CD-ROM library and can perform all required processing. On the client side, according to Wesley Cruver, system operator at Kidz Online, "users see an interface that lets them click on a file, but no processing is done on the client. The client merely displays screen shots. All processing is performed in the server." Since the processing takes place on the server, even students with those old 286s can take advantage of the multimedia-intensive applications within the CD-ROM library.
The ICA protocol also accommodates the limited multimedia capabilities of older machines by providing near-LAN speed over low bandwidth, using thin client architecture. To accomplish its goals, the ICA protocol passes only graphics, terminal commands and keyboard commands to and from the client, as opposed to other remote access protocols that incorporate substantially more overhead.
The Kidz Online network consists of a Web server, mail server, BBS server and Terminal Server connected to an ADSL line. Inherent in the ADSL technology is a data transfer speed of 1.5 Mbps downstream and 384 Kbps upstream. All computers on the LAN are connected through a series of hubs and switches to the ADSL line. Although ADSL is the broad-band, high-speed transport, users can also use dial-in capabilities with a modem.
According to Phil Cruver, program manager for the Kidz Online Virtual CD-ROM Library Project, "the use of the broad-band technologies is great when you go from the client to the central office, but when you go from the CO to the Internet, who knows what will take place? That is why we wanted to incorporate the ICA protocol. It improves efficiency because not as much data is being transmitted."
Mike Peay, president of MP Computer Consulting (Sterling, Va.) and consultant with Kidz Online, says that the approach "is a viable solution to [make use of] inexpensive equipment."