Link Stability Based Hop By Hop Multicast Protocol For Vanets G.Mary Valantina, 1 Research scholar, Sathyabama University Chennai, India Valantina78@gmail.com Dr.S.Jayashri 2 Director Adhiparasakthi Engineering College, Melmaruvathur, Kanchipuram District, Tamilnadu,India. Jayaravi2010@gmail.com Abstract Vanets are new emerging and challenging technology that makes an improvisation in traffic safety and efficiency. The constant growth of automobile industry is increasing the demand for car safety and the car to car connectivity. It creates a path for intelligent transportation system(ITS).The information that is carried by the vehicles can enrol safety measures The group-oriented services are one of the primary application classes that are addressed by VANETs in recent years. To support such services, multicast routing is used. Thus, there is a need to design stable and reliable multicast routing protocols for VANETs to ensure better packet delivery ratio, lower delays and reduced control overheads. In this paper, we propose link stability based hop by hop multicast routing scheme that finds stable multicast path from source to receivers. The multicast path is constructed by using route request and route reply packets with the help of multicast routing information cache and link stability database maintained at every node. A multicast routing protocol that implements multicast distribution through recursive unicast trees. The main goals of LSHBH are to support unicast clouds, allowing incremental deployment to have a stable tree structure, by minimizing the impact of receiver departures, and to construct low-cost trees, to reduce administrative costs and to lower error rate. The proposed scheme is simulated over a large number of VANET nodes with wide range of mobility and the performance is evaluated. It is observed that proposed scheme produces better packet delivery ratio, less control overheads and reduced packet delay compared to on-demand multicast routing protocol (ODMRP). Keywords: ITS, link stability: multicast routing: ODMRP. 1. INTRODUCTION There are many characteristics and challenges that should be taken into consideration when developing multicast routing protocols, like the dynamically changing network topology, limitation of network scalability. There are different types of protocols like unicast protocols [1], [2], cluster based protocols [3] In this paper we discuss about multicast routing for vehicular Ad hoc network which is different from other Ad Hoc networks [4]. Generally there are two types of multicast routing protocols in wireless networks. Tree-based multicast routing protocol, mesh based routing protocol [5]-[8]. In the tree-based multicasting, structure can be very much unstable in multicast ad-hoc routing protocols, as it needs frequent re-configuration in dynamic network. One such example is Multicast extension for Ad-Hoc On-Demand Distance Vector (MAODV) and Adaptive Demand- Driven Multicast Routing protocol (ADMR). The second type is mesh-based multicast protocol. Mesh-based multicast routing protocols are more than one path may exist between a source destination pair, Core-Assisted Mesh Protocol (CAMP) and On-Demand Multicast Routing Protocol (ODMRP) are an example for these type of classification[9]. One approach to multicast is to maintain a multicast tree in straight roads. Existing protocols for multicasting encounters quite a lot of troubles in mesh maintenance and regular reconfiguration when link breakage occurs. The extreme dependency of these protocols on upstream and downstream nodes leads to storage and control overhead. Furthermore, various protocols consider the shortest path as a decisive factor for path selection, Existing forwarding state for the multicast distribution mesh for the source and the group. The nonexistence of data and Keep-alive messages within a certain period of time is an indication of forwarding mesh disconnection. Existing multicast protocols are either hybrid or mesh-based. Mesh-based schemes set up a single path connecting any two nodes in the multicast group. These schemes need least amount number of copies per packet to be sent along the branches of the mesh, therefore they are bandwidth efficient. On the other hand, as mobility increases, link failures start the reconfiguration of the G.Mary Valantina et.al / Indian Journal of Computer Science and Engineering (IJCSE) ISSN : 0976-5166 Vol. 5 No.2 Apr-May 2014 97