Abstract: A system for reliable multicast distribution includes a primary content engine and a backup content engine sender. The primary content engine sender sends out a multicast message of content to selected content engine receivers. The sender waits for negative acknowledgments from the selected content engine receivers declaring that content was not received. If a negative acknowledgment is received, the sender resends the multicast message a predetermined number of times. If the content is still not received after the number of multicast passes is exhausted, the sender sends out unicast messages to those receivers still requesting content. If the primary sender does not respond to a negative acknowledgment, the receiver sends a second negative acknowledgment to the backup multicast sender. The backup responds with the data requested in the negative acknowledgment and so is able to begin data distribution at the point where the primary sender left off without maintaining synchronicity with the primary sender.

Abstract: An apparatus and method for defining content distribution paths in a content distribution network integrate unicast and multicast connections. Content engines in the content distributed network are organized into channels with a master content engine maintaining specific content. The content distribution network is further organized into a distribution hierarchy based on network topology and channel definitions, first by establishing unicast paths through the content distributed network and then by integrating multicast paths into the unicast hierarchy. The further organization of the content distribution network establishes distribution trees from the channel masters to the network edges.