a method of using a point - to - point label switched path to transmit multicast data packets partially through a multiprotocol label switched network when one or more label switched routers of the mpls are not multicast label distribution protocol enabled . the p2p lsp can be used to transmit multicast data packets to the head end of a point - to - multipoint lsp created with mldp enabled lsrs . the p2mp lsp can be used to transmit the multicast data packets through the mpls network to intended receivers that are external to the mpls network . when configuring the p2mp lsp , an mldp enabled lsr receives a first message from a non - mldp enabled mpls core router in response to sending a label mapping message to the non - mldp enabled mpls core router . in response , a directed ldp session is created between the mldp enabled lsr and an edge lsr in one embodiment in response to receiving the first message from an mpls enabled core router . the directed ldp session can be used to transmit a label mapping message to an ingress lsr .