| 摘要 |
Multicast signals are transmitted from a source to user terminals via multicast paths through a set of nodes in a network. A first node, such as a 'last-hop' router, may send toward the source corresponding join and prune messages, the join message to establish a new multicast path from the source to a user terminal, and the prune message to discontinue the old multicast path from the source to the user terminal. The router sends the join message and the prune message over the new multicast path and the old multicast path. A second node located at the bifurcation of the new multicast path and the old multicast path detects the reception of both the join message and the prune message and steers, either directly or via delegated downstream nodes, the switch from the old multicast path over to the new multicast path without loss or undue duplication of packets sent from the source to the user terminal. |
