Senthil Arunachalam - Fremont CA, US
Sundher Narayanaswamy - San Jose CA, US
Isidoros Kouvelas - Redwood City CA, US
Ishan Wu - Cupertino CA, US
Toerless Eckert - Mountain View CA, US
Cisco Technology, Inc. - San Jose CA
A method, system, computer program product and apparatus are presented to enable a L2 network device, such as a bridge or switch, to control the flow of a multicast data stream to a connected router in response to control messages received from the router by the L2 network device. By controlling the flow of multicast data streams in this manner, there will be a corresponding reduction in wasted bandwidth due to unnecessary transmission of these multicast data streams and a reduction in processing overhead by the router due to analysis and dropping of unnecessary multicast frames. In one aspect of the present invention, the router can generate the control messages in response to receiving a data frame in a multicast data stream from the L2 network device. The router can determine whether a subscriber to that multicast data stream is connected downstream of the router and then transmit an appropriate control message to the upstream L2 network device, indicating whether the router does or does not have a downstream subscriber. In response to such a control message, the L2 network device can cease transmitting the multicast data stream to the router, if appropriate.