fasp File Transfer Compared to FTP

The following graphs compare file transfer throughput and transfer time for fasp file transfer and FTP file transfer in typical network scenarios. All fasp and FTP benchmarks are for file transfer tests run within the Aspera labs. In each test, a 1-gigabyte file was transferred between commodity Pentium-4 computers running Debian Linux, using a standard Debian Linux implementation of FTP and Aspera Scp for fasp file transfer. A nistnet network emulator was used to simulate network round-trip latency and packet loss conditions typical on the Internet. Actual FTP throughputs will depend on the particular implementation of FTP used, the operating system, and the particular network loss pattern, but the results shown are typical.

fasp vs. FTP on Gigabit Metropolitan and Wide Area Networks

Conventional TCP file transfer technologies such as FTP dramatically reduce the data rate in response to any packet loss, and cannot maintain long-term throughputs at the capacity of high-speed links. For example, the maximum theoretical throughput for TCP-based file transfer under metropolitan area network conditions (0.1% packet loss and 10 ms RTT) is 50 megabits per second (Mbps), regardless of bandwidth. The effective FTP throughput is even less (22 Mbps). In contrast, fasp achieves 100% utilization of high-speed links with a single transfer stream.

In the particular test shown, the fasp throughput on a gigabit ethernet MAN (509 Mbps) presses the disk read/write speed limits of the endpoint computers. Perhaps more important, fasp maintains this throughput even as latency and packet loss increase (505 Mbps at 200 ms/2%). FTP throughput degrades to about 550 Kbps under the same conditions. While this 1000X speed advantage over traditional TCP transfers is only evident on the fastest long-haul networks, it illustrates the difference in the fasp approach.