Managing multicast tree reachability with PIM

Currently, PIM-SM is the most deployed multicast routing protocol. It is fully receiver driven and does not give any feedback information when a tree building/maintaining failure occurs or when the requested resource is unavailable. After a detailed analysis of the PIM behavior, we propose a simple feedback mechanism reporting about such unreachabilities/failures. It is suitable for informing downstream nodes about problems/unavailabilities. Taking into account this information in the routers of a multicast domain can also reduce signalization messages and routers load. This mechanism is designed as an extension of the PIM-SM protocol.