Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Neighbor-Supporting Multicast Protocol (NSMP) <s> An ad hoc network is a multi-hop wireless network formed by a collection of mobile nodes without the intervention of fixed infrastructure. Limited bandwidth and a high degree of mobility require that routing protocols for ad hoc networks be robust, simple, and energy-conserving. This paper proposes a new ad hoc multicast routing protocol called Neighbor-Supporting Multicast Protocol (NSMP). NSMP adopts a mesh structure to enhance resilience against mobility. And NSMP utilizes node locality to reduce the overhead of route failure recovery and mesh maintenance. NSMP also attempts to improve route efficiency and reduce data transmissions. Our simulation results show that NSMP delivers packets efficiently while substantially reducing control overhead in various environments. <s> BIB001 </s> Multicast Routing Protocols in Mobile Ad Hoc Networks: A Comparative Survey and Taxonomy <s> Neighbor-Supporting Multicast Protocol (NSMP) <s> An ad hoc network is a dynamically reconfigurable wireless network with no fixed infrastructure or central administration. Each host is mobile and must act as a router. Routing and multicasting protocols in ad hoc networks are faced with the challenge of delivering data to destinations through multihop routes in the presence of node movements and topology changes. This paper presents the On-Demand Multicast Routing Protocol (ODMRP) for wireless mobile and hoc networks. ODMRP is a mesh-based, rather than a conventional tree-based, multicast scheme and uses a forwarding group concept; only a subset of nodes forwards the multicast packets via scoped flooding. It applies on-demand procedures to dynamically build routes and maintain multicast group membership. ODMRP is well suited for ad hoc wireless networks with mobile hosts where bandwidth is limited, topology changes frequently, and power is constrained. We evaluate ODMRP performance with other multicast protocols proposed for ad hoc networks via extensive and detailed simulation. <s> BIB002
Protocol Description. NSMP BIB001 is a source-initiated multicast routing protocol, and is an extension to ODMRP BIB002 . A mesh is created by a source, which floods a request throughout the network. Intermediate nodes cache the upstream node information contained in the request and forward the packet after updating this field. When any receiver node receives the route discovery packets, it sends replies to its upstream nodes. Intermediate nodes receiving these replies make an entry in their routing tables and forward the replies upstream toward the source. In the case where the receiver receives multiple route discovery packets, it uses a relative weight metric (which depends on the number of forwarding and nonforwarding nodes on the path from the source to the receiver) for selecting one of the multiple routes. A path with the lowest value of relative weight is chosen. Figure 24 illustrates how a multicast mesh is built. In order to maintain the connectivity of the mesh, the source employs local route discoveries by periodically transmitting local requests, which are only relayed to mesh nodes and multicast neighbor nodes (nodes that are directly connected to at least one mesh node) to limit flooding, while keeping the most useful nodes informed. Any new receiver wanting to join the multicast group must wait for one of these local requests to join the desired multicast group. Replies are sent back to the source to repair broken links. Only nodes away from the source by two hops or less can join the mesh with a local request. Otherwise, they have to flood the member request. Discussion. NSMP is aimed at reducing the flood of control packets to a subset of the entire network. It utilizes node locality to reduce control overhead while maintaining a high delivery ratio. NSMP favors paths with a larger number of existing forwarding nodes to reduce the total number of multicast packets transmitted. It is preferable to make the relative weight metric adaptive to variations in the network load conditions.