The Ad Hoc On Demand Distance Vector (AODV) Routing Algorithm is a routing protocol designed for mobile ad hoc networks. AODV is capable of performing both unicast and multicast routing. It is an on-demand algorithm, which means that it creates routes between nodes only as the source nodes want. It maintains these roads as long as the springs need them. Additionally, AODV forms trees that connect members of the multicast group. Trees are made up of the group members and the nodes needed to connect the members. AODV uses sequence numbers to ensure routes are fresh. It is loop-free, starts automatically, and scales to a large number of mobile nodes. AODV creates routes using a route request/route response query cycle. When a source node wants a route to a destination for which it does not yet have a route, it broadcasts a Route Request (RREQ) packet across the network. Nodes receiving this packet update their information for the source node and configure backward pointers to the source node in the routing tables. In addition to the source node's IP address, current sequence number, and broadcast ID, the RREQ also contains the most recent sequence number for the destination that the source node is aware of. A node receiving the RREQ may send a Route Reply (RREP) if it is either the destination or has a route to the destination with a matching sequence number greater than or equal to that contained in the RREQ. If so, it returns an RREP to the source. Otherwise, it rebroadcasts the RREQ. Nodes keep track of the source IP address and broadcast ID of the RREQ. If they receive an RREQ that they have already processed, they reject the RREQ and do not transmit it. As the RREP propagates towards the source, the nodes are configured...... middle of paper ...... tree for the life of the multicast group. Since network nodes are mobile, it is likely that many link breaks along a route will occur over the lifetime of that route. The articles listed below describe how link breaks are handled. The WMCSA document describes AODV without multicast but includes detailed simulation results for networks of up to 1,000 nodes. The Mobicom article describes how AODV multicast works and details the simulations that show how it works. The Internet versions include descriptions of unicast and multicast route discovery, as well as how QoS and subnet aggregation can be used with AODV. Finally, the IEEE Personal Communications document and the Infocom document detail an in-depth study of simulations comparing AODV to the Dynamic Source Routing (DSR) protocol, and examine the respective strengths and weaknesses of each protocol.