InfiniBand Is Losing the Fabric War. Here's What That Changes for Your Architecture.

The InfiniBand vs RoCEv2 decision has been settled at the hyperscaler level — and the answer is Ethernet. Broadcom's March 2026 earnings confirmed it: roughly 70% of new AI infrastructure deployments are now choosing Ethernet-based fabrics over InfiniBand. That didn't happen because Ethernet got faster. It happened because InfiniBand ran out of room. InfiniBand Didn't Lose on Performance Let's be precise about what the shift actually means. InfiniBand remains technically superior for a specific class of problem: tightly coupled, homogeneous, single-vendor GPU clusters running large-scale distributed training in a controlled environment. At that workload, InfiniBand's latency characteristics and RDMA implementation are still genuinely differentiated. The shift isn't a performance verdict. It's an ecosystem verdict. InfiniBand is losing because of operational isolation, vendor lock-in, and scaling friction in the environments where enterprise AI actually runs — not because RoCEv2 won a l