Ethernet · RoCE · InfiniBand
AI Fabric Spine-Leaf Calculator
Turn GPU server connectivity into a reviewable leaf, spine, pod and media plan. The calculator keeps physical cages separate from logical breakout ports and labels future or silicon-only platforms as planning references.
Sizing result
How the sizing works
Endpoint links are placed either in pooled leaf capacity or isolated GPU rails. The solver enumerates whole physical-cage splits, rejects splits above the oversubscription target, then checks spine radix, a two-tier pod ceiling and one-spine failure capacity.
oversubscription = (D × endpoint rate) ÷ (U × uplink rate)
Planning boundary
This is an architecture and quantity estimate, not an orderable bill of materials. Breakout support, optics, cable reach, firmware, power, cooling, rail mapping and exact SKU availability still require vendor qualification.
Platform evidence
Port profiles and availability labels come from the linked vendor sources. Capacity is normalized to line rate in one direction so full-duplex marketing totals are not accidentally doubled.
Platform evidence (2026-07-26)
| Vendor / model | Protocol | Line rate | Status |
|---|---|---|---|
| Broadcom Tomahawk 5 BCM78900 | ethernet | 51.2 Tb/s | Silicon reference — select a shipping system for procurement |
| Broadcom Tomahawk 6 family | ethernet | 102.4 Tb/s | Silicon reference — system profiles vary |
| Juniper QFX5240-64OD | ethernet | 51.2 Tb/s | Current documented platform |
| Juniper QFX5250-64OE-L | ethernet | 102.4 Tb/s | Shipping; confirm exact orderability |
| Arista 7060X6-64PE | ethernet | 51.2 Tb/s | Current product |
| Arista 7060XE7-64PS | ethernet | 102.4 Tb/s | Planning reference — announced availability Q4 2026 |
| Arista 7800R4-AI | ethernet | 460.8 Tb/s | Catalog reference — modular chassis solver required |
| Cisco N9364E-SG2-O | ethernet | 51.2 Tb/s | Current documented platform |
| Cisco N9364E-SP2R | ethernet | 51.2 Tb/s | Current documented spine |
| Cisco N9164E-NS4-O | ethernet | 51.2 Tb/s | Planning reference — confirm SKU lifecycle and orderability |
| Ruijie RG-S6990-64OC2XS | ethernet | 51.2 Tb/s | Current product page |
| Ruijie RG-S6990-128QC2XS | ethernet | 51.2 Tb/s | Current product |
| NVIDIA SN5400 | ethernet | 25.6 Tb/s | Current documentation; confirm exact SKU/NOS lifecycle |
| NVIDIA SN5600 | ethernet | 51.2 Tb/s | Current documentation; confirm exact SKU/NOS lifecycle |
| NVIDIA SN5610 | ethernet | 51.2 Tb/s | Current documentation; confirm exact SKU/NOS lifecycle |
| NVIDIA SN3420 | ethernet | 4.8 Tb/s | Model disambiguation only |
| NVIDIA QM9700 | infiniband | 25.6 Tb/s | Mass Production |
| NVIDIA QM9790 | infiniband | 25.6 Tb/s | Mass Production |
| NVIDIA Q3400-RA | infiniband | 115.2 Tb/s | Planning reference — NVIDIA lifecycle P-Rel |
| NVIDIA Q3450-LD | infiniband | 115.2 Tb/s | Prototype planning reference |