For the industry it is important to have deterministic reaction times for time-critical applications. These applications run on distributed systems that are connected via a network. Real-time communication is therefore essential to ensure that the real-time behavior is maintained. Thereby, identical information needs to be distributed to multiple members of the network. Multicast is great for sending the same data to multiple destinations while keeping the network traffic minimal and saving resources. In this thesis we integrate multicasting in a conflict graph-based routing and scheduling approach for time-triggered streams. We especially look at the routing of the multicast streams. We present different methods to construct the route of multicasts on the data-link layer for joint routing and scheduling and empirically evaluate these methods. We discover that calculating up to four candidate path-trees already solves our joint routing and scheduling problem in most cases. Further, scheduling multicast streams becomes harder with an increasing number of destinations per stream. We confirm that multicast streams reduce the traffic compared to multiple unicast streams in the conflict graph-based routing and scheduling approach. We can route and schedule 842 multicast streams in 25 seconds for networks with 81 nodes. Traffic plan updates with 25 additional streams are generated in less than 3.3 seconds.