VANET is supposed to be an important technology which will contribute to smart transportation systems in future. Developing and analysing the operation of Vehicular Ad Hoc Networks (VANET) is generally based on a variety of environmental conditions combining different traffic models and routing protocols. However, it is not at all easy to implement vehicular scenarios where all the possible conditions and various traffic situations are appropriately modelled. For efficient communication between vehicles, routing is the most vital factor which needs to be considered. This paper comparatively analyses the functioning of various existing Position-based and Topology-based routing protocols for VANET and concludes about which protocols are suitable for different traffic scenarios. The paper also gives an introduction of a new concept of routing using Road side Units which would supposedly solve the mobility related issues of the existing routing protocols and would be suitable for all types of environments.