Although many multicast communication protocols have been recommended at IETF, reliable multicast communications currently rely on programs built at the application layer, e.g., multicast overlay. This is because there is a lack of reliable multicast protocols. This is even harder for the multicast capable routers to offer transparent reliable multicast services if receivers are on paths with drastically different path characteristics. In this paper, concept of multicast reliability integrated within routing algorithm is discussed. It is important to map reliability from transport layer to network layer, and subsequently from network layer to data link layer. The novelty of the proposed design is to offer packet recovery mechanisms between every two intelligent routers. The resulting shortest-hop based reliability eliminates the retransmission request implosion problem and shortens the error recovery session time along any multicast tree. Consequently, the proposed design offers high ...