Aria, a new product from California-based startup FastSoft, speeds up the transfer of any large file over the Internet, without requiring hardware or software on the receiving end. According to Dan Henderson, FastSoft's vice president of product and market development, a 700-megabyte movie file that takes 50 minutes to download regionally via a cable-modem connection can be downloaded in 34 minutes if the sender uses Aria. Overseas transfers show a bigger difference, with the same 700-megabyte movie taking nearly eight hours to download from Asia via a cable modem, and about 45 minutes with Aria.

Darin Harris, chief information officer of the movie-production company the Post Group, says that his company has seen files that normally take a day to download go through in a couple of hours. Harris says that he was attracted to Aria in part because only the sender needs to own hardware, and recipients don't need to know anything about Aria to get their files faster. All the sender has to do is connect the Aria appliance to his or her server.

Aria, which is based on research from the California Institute of Technology (Caltech), tries to make the most of the available bandwidth. Data usually isn't transferred at a line's full capacity. This is because the transmission control protocol (TCP) that governs 90 percent of the traffic flow over the Internet hasn't kept up with the times.

A 20-year-old algorithm, TCP is designed to make sure that information sent is reliably received, and to watch for congestion in the network. Standard TCP, sometimes called Reno, works by carefully increasing the rate at which it sends information until it detects that a packet of information has been lost. Reno interprets the loss to mean that the network is too congested to handle that rate of flow, and it cuts its transfer rate in half. Lachlan Andrew, a Caltech researcher who studies the algorithms behind Aria, compares this to a driver who accelerates slowly up to the speed limit, then slams on the brakes. When connection speeds were slower, this pattern wasn't a problem; now that industrial connections are available at speeds of 155 megabits per second, it is. "Reno is really being stretched to its breaking point," says Steven Low, cofounder of FastSoft and head of the Netlab research group at Caltech.

Caltech researchers designed FastTCP, the algorithm behind Aria, to improve on Reno. In academic trials, Henderson says, FastTCP has set data-transfer records, transferring data at a sustained rate of 101 gigabits per second. That's equivalent to transmitting the contents of the Library of Congress in 15 minutes.