Efficient method for storing multicast trees

A node for an ATM network comprising:

• a forming mechanism for forming multicast connections in the network which do not have overlapping branches as parties are added or deleted from the connections;
• a port mechanism which connects to the network through which the multicast connections are sent to the network, said forming mechanism connected to the port mechanism;
• and
• a memory connected to the forming mechanism having information about each connection necessary to ensure that the forming mechanism forms multicast connections which do not have overlapping branches as parties are added or deleted from the connections, the information about each connection includes a path of nodes, links and leaves which define each connection, the links, nodes and leaves of each path is represented by a tree graph stored in electrical form in the memory, the forming mechanism maintains a reference count for each PNNI branch of each path, and whenever a reference count becomes 0, the associated PNNI branch is deleted, where a reference count of a PNNI branch is equal to the number of the child branches, and a leaf branch is deleted when its corresponding leaf is removed from the connection.

A method for forming multicast connections comprising the steps of:

• forming a first connection between a first node and a second node;
• forming multicast connections from the first node with additional nodes without the multicast connections having any overlapping branches as parties are added or deleted from the connections;
• and
• forming a second multicast connection between the first node and a third node by extending the first connection, each node has a memory and each connection defines a path of nodes, links and leaves and before the multicast forming step there is the step of storing the links, nodes and leaves of the path of each connection as represented by a tree graph in electrical form in the memory, at least one connection comprises leaves, links and nodes of a path across a single PNNI which defines a DTL, and the forming a connections step includes the steps of adding a leaf to the path, and adding links used in the DTL that are not already on the tree graph to the tree graph and the leaf is added to the last link added to the tree graph.