Radio Astronomers Rely on End-to-End Network Performance Tools
Radio astronomers have long linked together multiple antennas to help them observe the farthest reaches of the universe. Until recently, however, because international networking could not meet the performance demands of correlating real-time data from two antennas in separate countries, the flexibility and scalability of this technique—also known as Very Long Baseline Interferometry (VLBI)—has been limited. However, in March 2004, with help from tools developed by the Internet2 End-to-End Performance Initiative, the first real-time international transmission and processing of VLBI data was conducted between the Massachusetts Institute of Technology (MIT) Haystack Observatory antenna and the Swedish Onsala Space Observatory antenna, ushering in a new era of network-enabled VLBI, or “e-VLBI.”
In the testing phase leading up to this milestone, an engineer at MIT discovered that the network between Haystack and Onsala was not delivering the performance required by the experiment. By using the Bandwidth Control (BWCTL) component of the Internet2 E2E piPEs, the engineer was able to pinpoint a network congestion problem in the Haystack Observatory area. As a result, this bottleneck link was corrected in March 2004, in time for the scheduled VLBI experiment.
Similarly, when setting up tests with Kashima Space Research Center, Japan, in May 2004, MIT discovered that the performance was far less than would be expected given the bandwidth of the network links between the two sites. MIT again used BWCTL to quickly isolate the cause of the performance problem to a faulty network interface on a server. As a result, MIT was able to replace the interface just in time for the e-VLBI experiment and, in collaboration with Japanese colleagues, conduct this kind of e-VLBI experiment in less than one quarter of the time it previously took.