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I noticed that setting the seed-set in the "ini" file for a Veins-OMNET++ simulation, will only affect the communication-related values by comparing different runs at a specific time. i.e. at a particular time for different runs, the vehicles' mobilities values (x,y, speed, direction) are relatively the same. Could you please confirm that? However, when I set the <seed value="seedValue" /> in the "mapname.launchd.xml" file, the mobilities of the vehicles change between runs. My second question is, Is changing the seed for SUMO affect the traffic flow (veh/h) set in the route file (.rou.xml)?

Fady Samann
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seed-set controls OMNeT++/Veins parameters defined as random variables in your omnetpp.ini file, something like **.packetSize = uniform(100B, 500B). SUMO's seed does the same job on the SUMO side. I assume you use VeinsInetMobility in your scenario -- in that case your speed and positions distribution is controlled by SUMO's seed since all computations are happening there, if you use any of inet's internal mobilities and set it in omnetpp.inifile -- then it is controlled by seed-set.

gehirndienst
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  • Thank you for the answer. You confirmed what I thought. However, do you know if the seed of SUMO changes the traffic flow values that I set in the rou.xml file? – Fady Samann Feb 16 '23 at 15:47
  • @FadySamann from the [official guide](https://sumo.dlr.de/docs/Simulation/Randomness.html): "The simulation uses multiple RNG instances to decouple different simulation aspects: a) randomness when loading vehicles (typeDistribution, speed deviation,...), b) probabilistic flows, c) vehicle driving dynamics. d) vehicle devices – gehirndienst Feb 16 '23 at 15:51
  • Yes, but in terms of the probabilistic flows, I tried two rou files with high and low traffic flows and different seeds. The simulations gave me as expected large number of vehicles for the high-traffic flow scenario and a smaller number of vehicles for the low-traffic flow scenario. So, I guess the seed of SUMO did not effect the flow set in rou file – Fady Samann Feb 16 '23 at 16:46