Topic

Network Architecture_

The network fabric connecting GPUs is as critical as the GPUs themselves. A poorly designed or improperly cabled network turns a $50 million GPU cluster into an underperforming asset. AI training workloads are communication-intensive: distributed training requires constant synchronization across hundreds or thousands of GPUs, and network bottlenecks directly translate to wasted compute cycles and longer training times.

Leviathan Systems Scope_

Leviathan Systems installs and tests the physical network infrastructure for GPU clusters, including InfiniBand NDR/XDR cabling, 400GbE Ethernet fabric, NVLink Switch configurations, and management networks. Our network testing validates throughput, latency, and error rates before the cluster enters production.

Resources_

What Is InfiniBand?What Is NVLink?What Is RDMA?What Is a Fat-Tree Topology?Network Testing Services

Articles_

Transceiver Breakout & Splitter Cabling for GPU FabricsDetails field procedures for deploying 2x and 4x breakout cables from high-speed switch ports to GPU NICs in scale-out InfiniBand or Ethernet fabrics, covering selection, routing, testing, and failure avoidance for GPU cluster deployments.NVIDIA Spectrum-X vs Quantum InfiniBand: The Cabling and Optics ViewThis article compares Spectrum-X Ethernet and Quantum InfiniBand fabrics strictly through the cabling, optics, and topology tasks performed by field crews during NVL72-class rack deployments, including switch port mapping, MPO trunk routing, and link validation steps.Optical Transceiver Handling & Cleanliness on the FloorDetails ESD controls, dust cap discipline, end-face inspection, and insertion sequences that prevent contamination and damage in 400G+ scale-out optics during rack integration and acceptance testing.Back-End vs Front-End Network Build-Out for GPU ClustersDetails the physical and logical separation of intra-rack copper NVLink backplanes from inter-rack MPO-based scale-out fabrics in H100-to-GB300 NVL72 deployments, including routing rules, test sequences, and field failure patterns that affect commissioning timelines.Building the Leaf-Spine Cable Plant for a GPU FabricDetails the physical leaf-spine fiber plant construction for AI scale-out fabrics, covering trunk routing, polarity control, inspection sequences, and verification steps that crews follow when connecting GPU racks via InfiniBand or Ethernet.InfiniBand NDR/XDR vs RoCE: What Changes for the Cable PlantDetails how choosing InfiniBand NDR/XDR versus RoCE for the scale-out fabric changes MPO trunk selection, patching sequences, cleaning protocols, and test parameters during rack deployment and inter-rack cabling for GPU clusters.Validating an InfiniBand Fabric with ibdiagnet: Errors, Width, and RoutingThis article details the exact ibdiagnet command sequence and output checks required to confirm every InfiniBand scale-out link in an NVL72-class deployment trains at full width and speed before cluster handover.400G vs 800G vs 1.6T Optics: Selecting Transceivers for AI FabricThis article gives deployment engineers explicit criteria for matching 400G/800G/1.6T transceivers to switch ports, fiber reach, and MPO infrastructure in AI scale-out fabrics while keeping NVLink copper domains separate.Rail-Optimized vs Fat-Tree: The Field Wiring Plan, Port by PortA field engineer's definitive guide to physically wiring and patching rail-optimized versus fat-tree InfiniBand/Ethernet fabrics in AI data centers, port by port, including common failure modes and testing procedures.Spectrum-X vs InfiniBand: What's Different for the Cable PlantA field engineer’s practical breakdown of how Spectrum-X and InfiniBand back-end networks differ for the cable plant in AI data centers, focusing on optics, fiber types, and installer workflow—and why the differences are smaller than most expect.

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