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Winter 2009 - 2010. Planet Lab - Sensor Network Batel Bibas & Eliran Cohen Supervisor – Ittay Eial. Figure 2. Findings In our experiment we used a ~300 computers, each computer had 20 neighbors The computers' measured values were chosen uniformly at random between 1 and 100 .
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Winter 2009 - 2010 Planet Lab - Sensor Network Batel Bibas & Eliran Cohen Supervisor – IttayEial Figure 2 Findings In our experiment we used a ~300 computers, each computer had 20 neighbors The computers' measured values were chosen uniformly at random between 1 and 100. Figure 1 shows the start values and the end values of each computer. At the end of the experiment all the computers obtain the same average number. Y axis represent the value of the selected computer, X axis represent the time Introduction A set of computers connected to the internet can be seen as a sensor network - measuring and sharing data. Data measurement for computers set can be very useful. For example, measuring the number of access to web server can be used to detect and prevent DoS attack for the whole servers set. This project models a sensors network. To model this network we used PlanetLab - a large set of computers spread all over the world, available as a testbed for computer networking and distributed systems research. In this project we used push/pull-sum protocol [1] to perform a distributed and highly efficient average calculation of the measurements. In our experiment, each computer acts as a sensor. It measures data and then performs a calculation according to the distributed protocol. Figure 1 Figure 3 shows the bandwidth usage for the whole system. At 9:59:00 the computers started to send messages and at 10:04:20 the experiment ended. Figure 3 Y axis represent the computer value, X axis represent the machine number , 1 to 290. Figure 2 shows the convergence time for an arbitrary computer. The value measured by this computer was ~84 and the calculated average was ~46. Here we can see that the value is stabilized after ~60 sec. Y axis represent the bits used by the whole system, X axis represent the time • Conclusions • We have shown by experiment that the Push/Pull-Sum protocol enables to calculate the average fast and with low bandwidth. • PlanetLab is a good platform for experimenting on the Internet. Is supplies a mass of computers that act in the real world. [1] Kempe, D., Dobra, A., & Johannes, G. (n.d.). Gossip-Based Computation of Aggregate Information. Retrieved from http://www-bcf.usc.edu/~dkempe/publications/aggregation.pdf