GPU Networking Cost Estimation for Cluster Planning

GPU networking cost estimation includes the interconnect fabric (switches, optics, cables), the bandwidth tier, RDMA support, and the topology's oversubscription ratio — line items that can equal or exceed GPU cost in large clusters but are often underestimated in initial budgets. For the networking requirements, see networking requirements for AI. For the GPU-level cost, see GPU cost calculation.

Networking Cost Components

Interconnect fabric: InfiniBand or high-speed Ethernet switches, optics, and cables — the hardware that carries GPU-to-GPU traffic. Cost scales with port count, speed tier, and whether the fabric is non-oversubscribed (each GPU's bandwidth is fully served) or oversubscribed (bandwidth shared, cheaper but throttles performance). Topology and scale: a fully non-oversubscribed fabric at large scale (hundreds of GPUs) can cost significantly — the switch hierarchy grows with GPU count. An oversubscribed fabric is cheaper but caps performance when GPUs communicate under load. RDMA: both InfiniBand and RDMA Ethernet require RDMA-capable NICs and switches, which are premium-priced versus standard Ethernet. Bandwidth tier: 200G, 400G, and 800G links cost progressively more. For how the fabric affects performance, see GPU cluster networking requirements.

FAQ

How much does GPU cluster networking cost?

It scales with GPU count, speed tier, and oversubscription ratio. At scale, networking can be a significant fraction of total cluster cost. A non-oversubscribed 400G RDMA fabric costs more than an oversubscribed design but does not cap GPU performance. Estimate networking alongside GPUs in the total budget. See the components above.

Summary

GPU networking cost is driven by fabric, topology, RDMA, and bandwidth tier — estimate alongside GPUs. For the full framework, see networking requirements.