Survey

Abstract

Vehicular Ad-hoc Networks (VANET) is wireless ad-hoc network including a set of vehicle nodes. It is a subclass of Mobile Ad-hoc Network (MANET). The high velocity of nodes constitutes the main difference between VANET and MANET. This distinguished specificity leads to an unpredictable topological change. Like any ad hoc network, routing is the very important step in VANET network. There are several routing protocols proposed for VANETs. The classification of these routing protocols is made based on some criteria. In this paper, we are interested in the type of diffusion of message issue in the network. There exist three types: unicast protocol, broadcast protocol and multicast protocol. The multicast protocol includes two subclasses: geocast and cluster-based protocols.. After analyzing the new routings protocols for VANETs, we observed the emergence of new technology carry-and-forwarding. This latter is the new axis for designing routing protocol in VANETs. Some of the problems, encountered during the development of routing protocol for VANETs, are the rapid change of topology and the frequent disconnection, which make the routing of packets a difficult task in VANETs.