Distribution of data packet via overlay tunnel connecting multicast trees utilizing a fat tree network topology

An apparatus implemented as a physical machine, the apparatus comprising:

• non-transitory machine readable media configured for storing executable machine readable code;
• a device interface circuit configured for communications in a data network;
• and
• a processor circuit configured for executing the machine readable code, and when executing the machine readable code operable for:
• causing establishment of first and second multicast trees within one or more underlay switching fabrics of one or more fat tree topologies, the first and second multicast trees comprising respective first and second multicast roots for multicast transmission to leaf network devices in the respective first and second multicast trees;
• causing establishment of an overlay tunnel between the first and second multicast roots, the overlay tunnel independent and distinct from the first and second multicast trees;
• causing the first multicast root to multicast transmit, via the first multicast tree, a data packet having been transmitted to the first multicast root;
• and
• causing the first multicast root to unicast transmit the data packet to the second multicast root via the overlay tunnel, for multicast transmission of the data packet by the second multicast root via the second multicast tree.

One or more non-transitory tangible media encoded with logic for execution by a machine and when executed by the machine operable for:

• causing, by the machine, establishment of first and second multicast trees within one or more underlay switching fabrics of one or more fat tree topologies, the first and second multicast trees comprising respective first and second multicast roots for multicast transmission to leaf network devices in the respective first and second multicast trees;
• causing, by the machine, establishment of an overlay tunnel between the first and second multicast roots, the overlay tunnel independent and distinct from the first and second multicast trees;
• causing the first multicast root to multicast transmit, via the first multicast tree, a data packet having been transmitted to the first multicast root;
• and
• causing the first multicast root to unicast transmit the data packet to the second multicast root via the overlay tunnel, for multicast transmission of the data packet by the second multicast root via the second multicast tree.