Petabits per rack: How AI traffic is reshaping networks

AI traffic is vastly different than the cloud and enterprise traffic that existing networks were built to carry. Training clusters running at petabit-per-rack bandwidth, zero-loss protocols, and microsecond synchronization are a new infrastructure challenge. Hyperscalers are spending over $600 billion in capex this year addressing the challenge. This report draws on 30 papers from OFC 2026, from Meta, KDDI, China Mobile, Samsung, TSMC, and others, to establish what the engineering record shows about how AI networks are built today, where the architecture is heading, and where the supply chain risk is highest. Our key conclusions are as follows: AI traffic is a different animal. Training clusters running at Petabit-per-rack bandwidth requirements…