Vehicular Ad-hoc Networks (VANET) is wireless ad-hoc networkincluding a set of vehicle nodes. It is a subclass of Mobile Ad-hocNetwork (MANET). The high velocity of nodes constitutes themain difference between VANET and MANET. Thisdistinguished specificity leads to an unpredictable topologicalchange. Like any ad hoc network, routing is the very importantstep in VANET network. There are several routing protocolsproposed for VANETs. The classification of these routingprotocols is made based on some criteria. In this paper, we areinterested in the type of diffusion of message issue in the network.There exist three types: unicast protocol, broadcast protocol andmulticast protocol. The multicast protocol includes twosubclasses: geocast and cluster-based protocols. After analyzingthe new routings protocols for VANETs, we observed theemergence of new technology carry-and-forwarding. This latter isthe new axis for designing routing protocol in VANETs. Some ofthe problems, encountered during the development of routingprotocol for VANETs, are the rapid change of topology and thefrequent disconnection, which make the routing of packets adifficult task in VANETs.