A Beginner’s Guide to Modern Ethernet Fabrics for HPC and AI Environments vendor-neutral fundamental, packet walks, AI/HPC design context , and troubleshooting Design Examples and Use Cases Small Example Fabric The following fictional example is deliberately small enough to draw but contains the same conceptual building blocks as a much larger fabric. Figure 20 –…

A Beginner’s Guide to Modern Ethernet Fabrics for HPC and AI Environments vendor-neutral fundamental, packet walks, AI/HPC design context , and troubleshooting Keeping the Lights On Fabric Automation and Source of Truth A fabric with hundreds of switches is mostly repeated structure: interfaces, addressing, AS numbers, VNIs, route targets, VRFs, and policy templates. Configuring those…

A Beginner’s Guide to Modern Ethernet Fabrics for HPC and AI Environments vendor-neutral fundamental, packet walks, AI/HPC design context , and troubleshooting EVPN/VXLAN in HPC and AI Environments Why AI and HPC Networks Are Different Enterprise applications often have diverse traffic patterns that average out statistically. Distributed AI training can be much more synchronized. Collective…

A Beginner’s Guide to Modern Ethernet Fabrics for HPC and AI Environments vendor-neutral fundamental, packet walks, AI/HPC design context , and troubleshooting Let’s Take Some Walks End-to-End Packet Walks Packet walks are the fastest way to turn EVPN/VXLAN from a vocabulary exercise into a working mental model. The following examples assume symmetric IRB, hardware leaf…

A Beginner’s Guide to Modern Ethernet Fabrics for HPC and AI Environments vendor-neutral fundamental, packet walks, AI/HPC design context , and troubleshooting Distributed Layer 2 and Layer 3 Services Anycast Gateway In an older design, a subnet’s default gateway might live on one pair of aggregation switches. A server attached elsewhere sends inter-subnet traffic toward…

A Beginner’s Guide to Modern Ethernet Fabrics for HPC and AI Environments vendor-neutral fundamental, packet walks, AI/HPC design context , and troubleshooting The one-sentence version EVPN, VXLAN, and BGP are related but different. VXLAN encapsulates traffic. EVPN advertises reachability. BGP transports routing information. The physical underlay forwards the outer IP packet.  The central mental model:…

A Beginner’s Guide to NVIDIA Spectrum and Spectrum-X Networking Spectrum vs ordinary switching, fabric thinking, history, and AI motivation Spectrum Networking Design Walkthrough Scenario A fictional organization is building an AI training and distributed-inference environment with 512 GPU servers across 16 racks. Each server has one 800G-class AI-network attachment represented here as two 400G ports…

A Beginner’s Guide to NVIDIA Spectrum and Spectrum-X Networking Spectrum vs ordinary switching, fabric thinking, history, and AI motivation Kubernetes and Cloud-Native Integration Kubernetes adds a scheduling and network-abstraction layer above the physical fabric. The cluster CNI handles ordinary pod connectivity, but high-performance AI pods may also need direct or virtualized access to RDMA-capable NIC…

A Beginner’s Guide to NVIDIA Spectrum and Spectrum-X Networking Spectrum vs ordinary switching, fabric thinking, history, and AI motivation High Availability and Resilience Clos fabrics are designed around the expectation that links and switches will fail. Resilience comes from parallel paths, fast control-plane convergence, sufficient spare capacity, and small failure domains. The goal is not…