System and method for allowing multiple global identifier (gid) subnet prefix values concurrently for incoming packet processing in a high performance computing environment

A system for using a global identification subnet prefix value in a network environment in a high performance computing environment, the system comprising:

• a first local subnet in an associated computer environment including a network fabric, the first local subnet comprising:
• a first network Host Channel Adapter (HCA) wherein the first network HCA comprises:
• a switch operatively coupled with a plurality of first ports for forwarding packets to a second HCA within the network fabric, and a special switch port representative of a boundary of the first local subnet within the network fabric relative to an associated intermediate switch fabric;
• a non-transient memory device storing a Linear Forwarding Table (LFT) mapping each of the plurality of first ports with a corresponding plurality of inputs to the LFT;
• logic stored in the non-transient memory device;
• and
• a processor operable to execute the logic,
• wherein a first packet is received from the network fabric by the first network HCA, the first packet including a Local Route Header (LRH) portion comprising a Destination Local Identifier (DLID) portion identifying a destination address of the first packet,
• wherein the logic is executed by the processor to determine whether the DLID portion of the first packet identifies the special switch port of the switch,
• wherein the logic is executed by the processor to, based on the DLID portion of the first packet identifying the special switch port of the switch:
• inspect the first packet to determine a Global Routing Header (GRH) portion of the first packet;
• generate an augmented packet for forwarding to the associated intermediate switch fabric by augmenting the DLID portion of the first packet with an Inter-Subnet-Route-Number (ISRN) portion of the GRH portion of the first packet;
• and
• forward the augmented packet to the destination address in the associated intermediate switch fabric via the special switch port of the switch.

A non-transitory machine readable medium having instructions stored thereon that when executed by an associated computer comprising a network fabric and a first subnet cause the associated computer to perform steps comprising:

• providing, in a computer environment including a network fabric, a first local subnet within the network fabric, the first local subnet comprising a first network Host Channel Adapter (HCA) wherein the first network HCA comprises:
• a switch operatively coupled with a plurality of first ports for forwarding packets to a second HCA within the network fabric, and a special switch port representative of a boundary of the first local subnet within the network fabric relative to an associated intermediate switch fabric;
• and
• a non-transient memory device storing a Linear Forwarding Table (LFT) mapping each of the plurality of first ports with a corresponding plurality of inputs to the LFT;
• receiving from the network fabric by the first network HCA a first packet including a Local Route Header (LRH) portion comprising a Destination Local Identifier (DLID) portion identifying a destination address of the first packet;
• determining whether the DLID portion of the first packet identifies the special switch port of the switch;
• and
• based on the DLID portion of the first packet identifying the special switch port of the switch:
• inspecting the first packet to determine a Global Routing Header (GRH) portion of the first packet;
• generating an augmented packet for forwarding to the associated intermediate switch fabric by augmenting the DLID portion of the first packet with an Inter-Subnet-Route-Number (ISRN) portion of the GRH portion of the first packet;
• and
• forwarding the augmented packet to the destination address in the associated intermediate switch fabric via the special switch port of the switch.