Fault-tolerant multicasting network

A multicasting network includes a number of routers that are connected together to form a ring. The routers include a source router that identifies incoming multicasting data packets, and forwards the multicasting data packets in both directions on the ring. The routers also include forwarding routers that identify incoming multicasting data packets, and forwards the multicasting data packets in only one direction on the ring. Further, each ring has two terminating routers that receive forwarded data packets on two external nodes, and accept forwarded data packets from only a first external node and not from a second external node. When a fault condition is detected that prevents data packets from being forwarded in a first direction on the ring, the routers down stream of the fault condition reconfigure themselves to receive forwarded data packets from the second direction.