Reliable multicast using a redundant unicast overlay network

A router comprising:

• a memory implementing one or more buffers;
• and
• processing circuitry in communication with the memory, the processing circuitry being configured to:
• receive first multicast packets of a multicast flow via a multicast distribution tree implemented in part between the router and one or more upstream routers;
• receive second multicast packets of the multicast flow via a transmission control protocol (TCP) connection of a connection-oriented distribution tree implemented in parallel to the multicast distribution tree,
• wherein the connection-oriented distribution tree is for replicating the second multicast packets of the multicast flow reliably and in order to the router, and
• wherein each packet of the second multicast packets is a copy of a corresponding packet of the first multicast packets;
• store the received second multicast packets to the one or more buffers implemented in the memory;
• in response to determining that the router has received a multicast packet of the first multicast packets via the multicast distribution tree out of order to create a gap of one or more of the first multicast packets for the multicast flow, forward, to at least one interested receiver positioned downstream of the router, the second multicast packets stored to the one or more buffers to close the gap.

A router comprising:

• a memory implementing one or more buffers;
• and
• processing circuitry in communication with the memory, the processing circuitry being configured to:
• transmit first multicast packets of a multicast flow to a downstream router via a multicast distribution tree implemented in part between the router and one or more downstream routers including the downstream router;
• transmit, to the downstream router, second multicast packets of the multicast flow via a transmission control protocol (TCP) connection of a connection-oriented distribution tree implemented in parallel to the multicast distribution tree, wherein the connection-oriented distribution tree is for replicating the second multicast packets of the multicast flow reliably and in order to the downstream router, and wherein each packet of the second multicast packets is a copy of a corresponding packet of the first multicast packets;
• store the second multicast packets to the one or more buffers implemented in the memory;
• and
• in response to receiving a selective acknowledgement (SACK) message from the downstream router indicating that the downstream router has received a multicast packet of the first multicast packets via the multicast distribution tree out of order to create a gap of one or more of the first multicast packets for the multicast flow, retransmit, to the downstream router, the second multicast packets stored to the one or more buffers to close the gap.