| Where are the PLE nodes today? ELTE's location survey |
| Monday, 28 June 2010 08:21 |
 In several research scenarios the geographic location of the measurement nodes plays a significant role. Such information is provided by the site information collection at PlanetLab Central. However, in this collection a relatively large number of the PlanetLab nodes are mislocated, with a varying magnitude of error.In order to enable more accurate results in this kind of experiment, the Onelab research team at OneLab innovation partners ELTE, led by Prof. Gábor Vattay, has developed a web-based calibration tool to gather reliable information on the location of PlanetLab Europe sites. With the help of the PlanetLab Europe support team at UPMC, all site administrators were asked to correct the geographic position of their PlanetLab nodes. As Figure 1 shows almost three quarters of the nodes were corrected, and the location of a further 15% of the nodes were approved, making 90% of PlanetLab node locations in Europe correct.  Figure 2 shows the probability distribution of error in node location. It can be seen that the distribution of error has a very long tail: some nodes had a larger error than the largest distance within Europe! Even though this might seem unreasonable, this was really the case, since some of the nodes were registered to the longitude and latitude coordinates of (0.0) and (1.1).Thanks to the calibration tool developed at ELTE and the overwhelmingly positive response from site administrators the error in the geolocation coordinates of PlanetLab Europe nodes has been reduced by several orders of magnitude. This development will allow researchers to conduct much more precise geographic experiments on the PlanetLab Europe infrastructure. For further information, contact This e-mail address is being protected from spambots. You need JavaScript enabled to view it . |
