Oversubscription
Provisioning less network bandwidth than full non-blocking would require; 1:1 is non-blocking, 3:1 is oversubscribed.
Current numbers
1:1 vs 2:1–3:1Published scale-out oversubscription examples: 1:1, 2:1–3:1 and a reported 7:1
31.6% combined VMS + 2:1 modeled savingSemiAnalysis Oct 2024 1,024-H100 model: 31.6% back-end saving from virtual modular switch plus 2:1 oversubscription vs NVIDIA reference
31.6% combined-design savingCombined layout and oversubscription saving in one training-cluster model