Network devices, systems, and methods, including executable instructions and/or logic thereon, are provided to discover a multicast router topology. A network device includes a processing resource coupled to a memory. The memory includes program instructions executed by the processing resource to discover a multicast router topology by determining a number of routers are connected to each other via a number of network connections and are running a multicast routing protocol (MRP) on a number of interfaces on the number of routers that are connected.