Outgoing interface mapping for multicast traffic

Multiple subscriber devices are connected to a network device via one or more network switches. The network device transmits multicast traffic to the subscriber devices. In particular, the network device may receive membership requests for a multicast group from the subscriber devices via the network switch on a first interface, i.e., a mapping interface. The network device sends a multicast stream associated with the multicast group to the network switch on a second interface, i.e. an outgoing interface (OIF). Upon receiving a membership request, the network device maps the membership request to an OIF dedicated to the multicast group. In this way, when multiple subscriber devices connected to the same switch request the same multicast stream, each membership request will map to the same OIF. The network device sends one copy of the multicast stream to the network switch on the dedicated OIF.