Multicast systems and methods for segment routing

A multicast method for Segment Routing includes, in a Segment Routing network with a plurality of nodes, wherein Segment Routing utilizes globally significant labels as node identifiers such that path state installation is only required at an ingress node of a Segment Routing domain, advertising a multicast flow by a source node; determining roles in the multicast flow for the plurality of nodes; and installing appropriate forwarding behavior for the multicast flow at the plurality of nodes based on the determined roles. The advertising can utilize Interior Gateway Protocol (IGP). For the multicast flow, source node segments are used to construct source routed trees rather than destination-based paths, wherein the source routed trees define broadcast paths, versus destination-based paths which are used in Segment Routing to define a node segment.