Hey there, let's break down why your vehicle count isn't matching the *.manager.numVehicles setting in your omnetpp.ini. I've run into similar issues with these exact versions, so here are the most common fixes to check:

• Check your SUMO route configuration first
  The numVehicles parameter in VEINS acts as a hint, but your SUMO routes file (usually routes.xml) might be overriding this. For example:

  • If you're using <flow> elements, make sure the number attribute isn't set to a lower value than your numVehicles. Also, check the end attribute—if it's set to a time earlier than your simulation ends, new vehicles will stop being generated before hitting your target count.
  • If you're using individual <vehicle> entries, SUMO will only spawn those exact vehicles, ignoring the numVehicles setting entirely. Switch to a flow-based setup if you want dynamic generation based on the VEINS parameter.

• Verify VEINS manager settings
  Double-check these parameters in your omnetpp.ini to make sure nothing's blocking vehicle generation:

  • Ensure *.manager.generateTraffic = true—if this is set to false, VEINS won't attempt to generate any vehicles, even if numVehicles is set.
  • Look for any other module-specific parameters that might override numVehicles. For example, if you're using a custom traffic manager module, it might have its own vehicle count setting that takes precedence.

• Make sure your simulation runs long enough
  If vehicles are being spawned at a steady rate (controlled by *.manager.vehicleSpawnInterval in VEINS), your simulation might end before all numVehicles are created. Calculate the required simulation time: numVehicles * vehicleSpawnInterval (plus a small buffer) and set sim-time-limit in omnetpp.ini to at least that value.

• Check for SUMO-VEINS sync issues
  Sometimes a misconfigured connection between the two tools can cause vehicle counts to be off:

  • When launching the simulation, check the console output for any errors related to SUMO connection or route loading. If SUMO fails to parse your route file correctly, it might not spawn all the vehicles VEINS requests.
  • Ensure that the SUMO step length (set in sumo.cfg via <step-length>) matches the OMNeT++ simulation step length to avoid desyncs that could halt vehicle generation prematurely.

If none of these fix the issue, try running a minimal test case—start with the default VEINS example (like the IEEE 802.11p demo), modify only the numVehicles parameter, and see if that works. If it does, the problem is likely in your custom configuration files.

内容的提问来源于stack exchange，提问作者sepideh