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Cornelis Technical Documentation

4.4. Multi-Rail Topologies

A multi-rail configuration provides load balancing and failover capabilities, adding a higher degree of fabric redundancy. If one SuperNIC or an entire Plane fails, traffic can be moved to the remaining Switches.

The multi-rail feature can be applied to a single plane or multiple planes, and by enabling multi-rail, the process can use multiple network SuperNICs to transfer messages.

Three multi-rail scenarios include:

  • Single-rail in a Single Plane: This scenario consists of one SuperNIC in a server connected to one plane. This is the default configuration during installation. This configuration provides the performance required by most applications in use today.

  • Dual-rail in a Single Plane: This scenario consists of two SuperNICs in the same server connected to the same plane. This configuration also provides improved MPI message rate, latency, and bandwidth to the node.

  • Dual-rail in Dual Subnets: This scenario consists of two SuperNICs in the same server connected to separate planes. Depending on the platform, this configuration may provide improved MPI message rate, latency, and bandwidth to the node.

Note

Other multi-rail scenarios can be configured. A single host Fabric Manager (FM) server can manage multiple planes up to the supported number of 0-7 Fabric Manager instances.