A mobile ad-hoc network (MANET) is composed of mobile nodes without any infrastructure. Mobile nodes self-organize to form a network over radio links. The goal of MANETs is to extend mobility into the realm of autonomous, mobile and wireless domains, where a set of nodes form the network routing infrastructure in an ad-hoc fashion. The majority of applications of MANETs are in areas where rapid deployment and dynamic reconfiguration are necessary and wired network is not available. These

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... military battlefields, emergency search, rescue sites, classrooms and conventions, where participants share information dynamically using their mobile devices. These applications lend themselves well to multicast operations. In addition, within a wireless medium, it is crucial to reduce the transmission overhead and power consumption. Multicasting can improve the efficiency of the wireless link when sending multiple copies of messages by exploiting the inherent broadcast property of wireless transmission. Hence, reliable multicast routing plays a significant role in MANETs. However, to offer effective and reliable multicast routing is difficult and challenging. In recent years, various multicast routing protocols have been proposed for MANETs. These protocols have distinguishing features and employ different recovery mechanisms. To provide a comprehensive understanding of these multicast routing protocols and better organize existing ideas and work to facilitate multicast routing design for MANETs, we present the taxonomy of the multicast routing protocols, their properties and design features. This paper aims to aid those MANETs researchers and application developers in selecting appropriate multicast routing protocols for their work.