TRILL (Transparent Interconnection of Lots of Links) facilitates loop-free connectivity to non-TRILL networks via a choice of an Appointed Forwarder for a set of VLANs. Appointed Forwarders provide VLAN-based load sharing with an active-standby model. Highperformance applications require an active-active load-sharing model. The active-active load-sharing model can be accomplished by representing any given non-TRILL network with a single virtual RBridge (also referred to as a virtual Routing Bridge or virtual TRILL switch). Virtual representation of the non-TRILL network with a single RBridge poses serious challenges in multi-destination RPF (Reverse Path Forwarding) check calculations. This document specifies required enhancements to build Coordinated Multicast Trees (CMT) within the TRILL campus to solve related RPF issues. CMT@ which only requires a software upgrade@ provides flexibility to RBridges in selecting a desired path of association to a given TRILL multi-destination distribution tree. This document updates RFC 6325.