Abstract: Vehicular Ad hoc Network (VANET) is an emerging sub-class of MANET. Recently VANET have emerged to turn the attention of researchers in the field of wireless and mobile communications. It is distinguished from other kinds of ad hoc networks by their hybrid network architectures, node movement characteristics, challenges and new application scenarios. It cellular technology to achieve intelligent inter-vehicle communications and improve road traffic safety and efficiency. Intelligent transportation and active security are important applications of VANET, which need suitable vehicle-to-vehicle communication and vehicle and roadside infrastructures technology, especially routing technology. It poses many unique networking research challenges and the design of an efficient routing protocol for VANETs is very crucial. The mobility models are used during the simulation of protocols. Routing protocols are design to address challenges, which includes heterogeneous networks, random topology and high mobility of nodes. They should generate movement pattern which reflects real world behaviour of vehicles on the roads. It has a very high dynamic topology and constrained mobility which makes the traditional MANET protocols unsuitable for it. In this article, we discuss some challenges, applications and various kind of attack with respect to security principles.

Keywords: VANET, routing protocols, possible attacks, Security.