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All of the compute and login nodes of Barbora are interconnected through a Mellanox InfiniBand HDR 200 Gbps network and a Gigabit Ethernet network.

Calculation nodes and the service infrastructure is connected by the HDR100 technology that allows one 200Gbps HDR port (aggregation 4x 50Gbps) divided into 2 HDR100 ports with 100Gbps (2x 50Gbps) bandwidth.

The cabling between the L1 and L2 layer is realized by HDR cabling, connecting the end devices is realized so called Y or splitter cable (1xHRD200 - 2x HDR100).

The computing network thus implemented fulfills the following parameters

  • 100Gbps
  • Latencies less than 10 microseconds (0.6 μs end-to-end, <90ns switch hop)
  • Adaptive routing support
  • MPI communication support
  • IP protocol support (IPoIB)
  • Support for SCRATCH Data Storage and NVMe over Fabric Data Storage.

Mellanox QM8700 40-Ports Switch


  • 40x HDR 200Gb/s ports in a 1U switch
  • 80x HDR100 100Gb/s ports in a 1U switch
  • 16Tb/s aggregate switch throughput
  • Up to 15.8 billion messages-per-second
  • 90ns switch latency

Optimized Design

  • 1+1 redundant & hot-swappable power
  • 80 gold+ and energy star certified power supplies
  • Dual-core x86 CPU

Advanced Design

  • Adaptive routing
  • Collective offloads (Mellanox SHARP technology)
  • VL mapping (VL2VL)

BullSequana XH2000 HDRx WH40 MODULE

  • Mellanox QM8700 switch modified for direct liquid cooling (Atos Cold Plate), with form factor for installing the Bull Sequana XH2000 rack