31.1.2.0.3 Shared Tree Mode

Simplified sparse mode ST.tcl is a version of a shared-tree multicast protocol. Class variable array RP
_ indexed by group determines which node is the RP for a particular group. For example:

        ST set RP_($group) $node0
        $ns mrtproto ST

At the time the multicast simulation is started, the protocol will create and install encapsulator objects at nodes that have multicast senders, decapsulator objects at RPs and connect them. To join a group, a node sends a graft message towards the RP of the group. To leave a group, it sends a prune message. The protocol currently does not support dynamic changes and LANs.