Many distributed multimedia applications involve data delivery from a source
to multiple destinations, the participating nodes forming a multicast
group. The group members are connected by a tree each source with the
participants as the leaf nodes or just have one tree spanning all the
participants. In this paper, we introduce an architecture for routing 
multicast trees over the ATM networks called Domainserver Hierarchy. Our work
will be an important milestone that will allow the recently proposed wide area
multicast protocols (like CBT and PIM) to be supported in hierarchical
internet routing protocols in general and specifically, the PNNI routing
protocol of ATM networks.