Patent ID: 8068481

Claim:
A method comprising: receiving, at a first router, a response message to a request message sent by a head-end router to a plurality of routers in a default multicast distribution tree (MDT), the response message including an indication to join a data MDT for a multicast stream, the default MDT being a multicast distribution tree that sends content for the multicast stream from a source to all of a plurality of routers in the default MDT, wherein the data MDT sends content for the multicast stream from the source to a portion of the plurality of routers that join the data MDT; determining a list of downstream routers that are connected to the first router using the default MDT, the list used in determining if all responses have been received from the downstream routers on the list, wherein the list is a default MDT list that includes all downstream routers that have joined the default MDT, and wherein there is a plurality of default MDT lists; determining from the default MDT if responses to the request message have been received from downstream routers of a predefined set of downstream routers; determining the routers of the predefined set from a default MDT replication list; determining if the responses indicate whether the downstream routers of the predefined set join or do not join the data MDT; and sending, by the first router, a first router response message upstream based on the responses received, the first router waiting until it is determined that all responses have been received from the downstream routers, wherein the head-end router uses at least a portion of information in the first router response message to determine when to switch from the default MDT to the data MDT for the multicast stream such that the default MDT is not used to send content for the multicast stream, and wherein after the switch, downstream routers that did not join the data MDT do not receive the content for the multicast stream.