LISP Multicast Overlay Group to Underlay RLOC Mappings

This draft augments LISP [RFC9300] multicast functionality described in [I-D.farinacci-lisp-rfc6831bis] and [I-D.farinacci-lisp-rfc8378bis] to support the mapping of overlay group addresses to underlay RLOC addresses. This draft defines a many-to-1, 1-to-many, and many-to-many relationship between multicast EIDs and the Replication List Entries (RLEs) RLOC records they map to. The mechanisms in this draft allow a multicast LISP overlay to run over a mixed underlay of unicast and/or multicast packet forwarding functionality.