5.1 Why AI Networks Are Different
What transport and congestion control are, what you already know from running enterprise networks, and why AI training breaks the everyday baseline.
5.2 Transport Options
The four families of transport you'll meet in AI fabrics — classic IP, RDMA, hyperscaler-custom, and scale-up — told in three eras and a tabbed comparison.
5.3 Congestion Control Options
Every congestion control algorithm you'll meet in an AI fabric — TCP family, datacenter / RDMA, hyperscaler-custom, and research — told in three eras and a tabbed comparison.
5.4 Hyperscaler RoCE Stacks
The transport + congestion-control stacks the 9 hyperscalers actually run. Meta DSF cells + VOQ, Google Swift + Falcon + Aquila, NVIDIA Spectrum-X, Microsoft DCQCN at 400G, AWS SRD packet spraying, Alibaba HPCC, xAI single-socket, plus the UEC 1.0/1.1 roadmap and which NICs ship UEC. Comparison matrix included.