I read about OpenStreetMap used for SUMO, which kind of such mapping sources that can be exploited by SUMO to be evaluated by Omnetpp for VANET routing simulations?
In case, instead of using maps and SUMO, you can also use traffic traces, i.e. files describing the positions of vehicles in time. Traffic traces are obtained with real or realistic positions of vehicles in time. The only drawback is that the movements of vehicles cannot be changed during the simulation, but this is normally not needed for routing simulations.
For example, our traffic traces in the area of Bologna are available at:
A. Bazzi, B. M. Masini, A. Zanella, A. Calisti, "Visible Light Communications as a Complementary Technology for the Internet of Vehicles", accepted for publication in Elsevier Computer Communications, Special issue on Multi-radio, Multi-technology, Multi-system Vehicular Communications, DOI:10.1016/j.comcom.2016.07.004.
Other known traffic traces, referring to the city of Cologne, can be found at: