Abstract: In one embodiment, a device within a first network may learn a plurality of multicast traffic sources, and may join a first source-specific group for a particular group and a second source-specific group for the particular group. Subsequently, the device may receive multicast traffic from within the first network from at least one of the source-specific groups, select which received traffic to transmit down a non-source-specific shared multicast tree of a second network for the particular group, and transmit the selected traffic down the shared multicast tree for the particular group. In one embodiment, a receiver device in the second network may join the non-source-specific shared multicast tree to receive the traffic for the particular group.