Fueling faster file transfers with RocketStream
- 14 August, 2007 09:10
The data that we send over wires travels between two-thirds and three-quarters the speed of light, depending on the medium. Within the LAN, transfers from point A to point B appear to be immediate, with less than a millisecond delay.
However, if we stretch the length of those wires to thousands of miles, even at those speeds, we'll begin to see delays, a hundred milliseconds perhaps. The routers, gateways, and other gears found along the route may add a few more milliseconds.
Why is that a problem? Because when we combine that infinitesimal hiccup with a talkative protocol such as TCP/IP, which demands an acknowledgment for nearly each fragment of data sent, those milliseconds are compounded with each exchange, fast adding up to a serious annoyance.
As a consequence, the copying of a file, which takes only seconds between neighboring PCs, ends up taking minutes if not hours to crawl across a continent. As more and more companies tend to work and exchange files long-distance, it's not a surprise that companies such as Brocade and Cisco are proposing WAFS (wide area file system) solutions.
WAFS doesn't make those electrons move faster, but it minimizes the delays by using a shrewd combination of more efficient transport protocols and intelligent data mirroring.
For customers with deep pockets and needs that go beyond simple file transfers, a WAFS solution may be the ticket, but it could be too expensive if you only want to move files faster than TCP/IP and allow FTP over long distances.
RocketStream's eponymous application suite could fill that gap. The suite is founded on RocketStream's proprietary PDP (Parallel Delivery Protocol), which harvests the best characteristics of TCP and UDP (User Datagram Protocol) and adds features such as on-the-fly data encryption and compression.
RocketStream claims its suite provides better than 100 times the performance of FTP. I haven't had the chance to observe how the application works over a link with heavy latency, but the results of some local tests I ran are quite promising.
In fact, even on my LAN where the latency delay is very low, RocketStream moved files between two Windows XP machines much faster than Windows Explorer -- nearly twice the speed. Obviously, PDP had an impact, but to dig a little deeper and pinpoint the differences between the two file transfer methods, I used a protocol analyzer. The results were quite surprising.
File transfers performed by Windows Explorer generated nearly all TCP transactions. By contrast, only 35 percent of the packets RocketStream created to move the same file were TCP, while the majority (65 percent) was UDP. That difference translates into fewer conversations between end points, greatly reducing one of the annoyances of TCP/IP, while maintaining the same reliability, RocketStream assures.
The amount of data sent over the wire is another interesting difference uncovered by the protocol analyzer. In fact, the compression algorithms of RocketStream shrank a 160MB file to little more than 84 million bytes, which obviously means less burden on the connection. Another nice touch: To prevent sucking your pipe dry, you can limit the amount of bandwidth used by RocketStream.
Although quite usable as is, the application is still evolving, and in a future release, RocketStream plans to add support for Mac and Linux to its user-friendly Windows GUI.
RocketStream estimates that its suite will cost between US$20 and US$10,000 per year, depending on the bandwidth and the complexity of the installation, which could be bad news for the more expensive WAFS solutions on the market -- that is, if you need it for file transfers only.