System and method for supporting inter subnet control plane protocol for consistent multicast membership and connectivity in a high performance computing environment

A method for supporting multicast forwarding across multiple subnets in a high performance computing environment, comprising:

• providing, at one or more computers, including one or more microprocessors, a first subnet, the first subnet comprising
• one or more switches, the one or more switches comprising at least a leaf switch, wherein each of the one or more switches comprise a plurality of switch ports,
• a plurality of end nodes, wherein the plurality of end nodes are interconnected via the one or more switches,
• a subnet manager, the subnet manager running on one of the one or more switches and the plurality of end nodes, and
• an inter-subnet manager, the inter-subnet manager running on one of the one or more switches and the plurality of end nodes;
• configuring a switch port of the plurality of switch ports on a switch of the one or more switches as a router port;
• configuring a second switch port of the plurality of switch ports on a second switch of the one or more switches as a second router port;
• interconnecting the first subnet with a second subnet via the router port and the second router port;
• and
• setting up a multicast group within the first subnet, the multicast group comprising a multicast global identifier (MGID), the MGID being a member of an inter-subnet partition (ISP).

A non-transitory computer readable storage medium, including instructions stored thereon for supporting multicast forwarding across multiple subnets in a high performance computing environment, which when read and executed by one or more computers cause the one or more computers to perform steps comprising:

• providing, at one or more computers, including one or more microprocessors, a first subnet, the first subnet comprising
• one or more switches, the one or more switches comprising at least a leaf switch, wherein each of the one or more switches comprise a plurality of switch ports,
• a plurality of end nodes, wherein the plurality of end nodes are interconnected via the one or more switches,
• a subnet manager, the subnet manager running on one of the one or more switches and the plurality of end nodes, and
• an inter-subnet manager, the inter-subnet manager running on one of the one or more switches and the plurality of end nodes;
• configuring a switch port of the plurality of switch ports on a switch of the one or more switches as a router port;
• configuring a second switch port of the plurality of switch ports on a second switch of the one or more switches as a second router port;
• interconnecting the first subnet with a second subnet via the router port and the second router port;
• and
• setting up a multicast group within the first subnet, the multicast group comprising a multicast global identifier (MGID), the MGID being a member of an inter-subnet partition (ISP).