Methods and apparatus for efficient IP multicasting in a content-based network

A system for performing multicasting over a cable network, comprising:

• a plurality of cable modems;
• a cable modem termination system in data communication with said plurality of cable modems;
• and
• a controller adapted to track the state of multicast transmissions to said plurality of cable modems, detect that a cable modem assigned to a first physical channel selects a combination of multicast transmissions available on a second physical channel, and cause said cable modem to switch from a first channel to said second channel.

In a cable television network that comprises a plurality of cable modems, a modem termination system and a plurality of physical channels allowing communication between said plurality of cable modems and said cable modem termination system, a method of operating comprising:

• monitoring a first cable modem receiving a first multicast transmission on a first physical channel;
• detecting a second cable modem assigned to a second physical channel receiving said first multicast transmission;
• and
• causing said second cable modem to switch to said first physical channel.

A method for operating a cable modem in a cable network, the method comprising:

• receiving IP packets on a first physical channel;
• generating a request to receive a multicast transmission;
• receiving information used as the basis of switching said cable modem to a second physical channel;
• and
• switching said cable modem to said second physical channel;
• wherein at least one other cable modem is simultaneously receiving said multicast transmission on said second physical channel.

Cable modem apparatus adapted to process network traffic comprising:

• a digital signal processing unit capable of processing data from a first physical channel;
• and
• a control unit configured to generate a request to receive a multicast transmission, to receive a message to switch from a first physical channel to a second physical channel in response to said request, and to configure said digital signal processing unit to process said second physical channel;
• wherein said message to switch from said first to said second physical channel is received only after it is determined that said multicast transmission has been previously established on said second physical channel.

In a cable network comprising a hub, a plurality of cable modems, and a set of physical channels providing communication between said hub to said cable modems, a method of operating said cable network to efficiently deliver multicast packetized transmissions, comprising:

• transmitting a multicast transmission list message from said hub to at least a portion of said cable modems, said message listing a set of multicast transmissions and at least one corresponding physical channel on which each multicast transmission is being transmitted;
• receiving a request to receive a first multicast transmission from said set of multicast transmissions;
• and
• configuring at least one of said cable modems to process a physical channel associated with said first multicast transmission based at least in part on said multicast transmission list message.

In a cable network having at least one cable modem termination system (CMTS) and a plurality of client devices in signal communication therewith, a method of providing a plurality of content channels to network subscribers, the method comprising:

• transmitting content over a first channel to a first cable modem associated with a first client device, said first client device being associated with a first subscriber;
• transmitting said content over a second channel to a second cable modem associated with a second client device, said second client device being associated with a second subscriber;
• and
• selectively switching said second cable modem to said first channel to provide a multicast transmission of said content to said first and second subscribers from said first channel.