Abstract: In an asynchronous transfer mode (ATM) communications system, all ATM switches in a multicast connection perform virtual path (VP) switching except those merge points which perform virtual channel (VC) switching to avoid VCI collisions. The merge points are ATM switches which can merge ATM traffic from at least two incoming links into an outgoing link. In a second approach, each merge point in a multicast connection performs VP switching, and dynamically dispenses VC switching when a VCI collision is detected. Specifically, to prevent further VCI collision, incoming ATM cells indicated by an odd VPI value are VC switched by the merge point while those indicated by an even VPI value are VP switched thereby.

Abstract: The distribution of multicast information in a communications network formed from a plurality of communications nodes, e.g., ATM switches, is enhanced by providing an efficient mechanism for routing a request to join a multicast connection to an originator of the multicast and an efficient mechanism for then connecting the requester to the multicast connection.

Abstract: The present invention extends the PNNI protocols to support hierarchical multicast routing and signaling for ATM networks. The invention utilizes an extension to a core-based tree algorithm. Instead of a single core node, core nodes are maintained in each peer-group and at each level of the hierarchy. The advantage of this is that one single core node is not overloaded. Additionally, this increases fault-tolerance because there are no single points of failure. As would be understood, the present invention is highly scaleable because of the hierarchical nature of PNNI. In addition, the scheme supports multiple senders and dynamic membership changes to the multicast group. Quality of service requirements can be negotiated during connection setup and are guaranteed during the course of the connection. Though some additional topological information has to be flooded in the peer-groups to compute efficient multicast routes, the overheads to the connection management are minimal.