In general, techniques are described for providing multicast communication in a seamless MPLS architecture, in which thousands of PE routers within different routing areas of the same AS require P2MP connectivity to receive multicast communication. In particular, the techniques enable building inter-area P2MP segmented LSPs within an AS by stitching together intra-area segments of the inter-area P2MP segmented LSPs. The techniques provide LSP hierarchy with segmentation to enable aggregation of congruent intra-area segments within a routing area into an intra-area aggregate LSP. The AS may use the BGP as the inter-area label distribution protocol, and each routing area within the AS may independently select one of the multicast MPLS protocols as its intra-area label distribution protocol. The seamless MPLS architecture may be used by private network instances, such as multicast VPLS instances, MVPN instances, and IP multicast instances.