Patent ID: 8761161

Claim:
A method comprising: determining, at a first router, whether to switch from broadcasting data on a default multicast distribution tree (MDT) to a data MDT, the first router configured to broadcast data from a source to a plurality of routers, the default MDT broadcasting the data to the plurality of routers, and the data MDT broadcasting the data to at least a subset of the plurality of routers; sending a request message from the first router to the plurality of routers to join the data MDT; determining, at the first router, a list of downstream routers that are connected to the first router using the default MDT, the list being 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; based on the list of downstream routers that are connected to the first router, determining, at the first router, that responses to the request message have been received from the plurality of routers, each response to the request message indicating whether each of the downstream routers join the data MDT; based on the responses to the request message, determining, at the first router, which of the plurality of routers comprises the subset of the plurality of routers that will receive content from the data MDT; and switching the first router to broadcast the data from the default MDT to the data MDT only after determining that responses to the request message have been received from the plurality of routers.