Topology discovery service for router-assisted multicast transport

Many existing proposals for introducing network support for multicast transport require the establishment of signaling paths among adjacent active routers in a session. We present a general-purpose, lightweight protocol to establish a signaling overlay among sparsely deployed active nodes. The resulting overlay is tied to the underlying multicast route and adapts to changes in its topology. In addition, we make this overlay available to other protocols by means of efficient communication primitives to provide reliable signaling between neighboring active routers. Our protocol and associated services can serve as a building block for a variety of active multicast services and greatly simplify their development. We describe its applicability for implementing several previously proposed services.