IP Multicast Support in MPLS

Multicast support in a Multipro-tocol Label Switching (MPLS) network has yet to be deened. An MPLS network consists of label switching devices such as ATM. This document discusses both dense-mode and sparse-mode IP multicast within the context of MPLS networks. Unlike unicast routing, dense-mode multicast routing trees are established in a data-driven manner and it is not possible to topologically aggregate such trees, which are rooted at diierent sources. In sparse-mode multicast, source-speciic trees may coexist with a core/shared tree, and it is not possible to assign a common label to traac from diierent sources on a branch of the shared tree. This leads us to suggest a per-source traac-driven label allocation scheme for supporting all three types of multicast (dense mode, shared tree, source tree) routing trees in a MPLS network .