I want to write a scalable VANET routing protocol in NS3, I aim to create a scenario with a number of vehicles and RSU using clustering technic. Is there a need to use SUMO and NETEDIT or writing it in NS3 enough?
You only need Sumo/netedit to create a mobolity trace file your nodes. there are mobility models in ns3. However to suit the scenarior you needed, you may use sumo
You can use SUMO to create a MAP for your VANET network. SUMO and NS3 can be combined either offline (create trace file from the mobility of SUMO to be used by the Ns2MobilityHelper within NS3) or online (use iTETRIS or VSimRTI which combine SUMO and NS3):
This Paper can help you in which I proposed a new solution for VANETs based on NDN: