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NVIDIA Q3400-RA (Quantum-X800)

144 × 800G in 4U. That is 115.2 Tb/s of switching through 72 OSFP224 cages.

144 logical ports through 72 physical cages. Each cage carries a module terminating 2 links, so optic counts do not equal port counts. See optics compatibility.

Breakout

A port faster than the endpoint it serves can be broken out when the speeds divide cleanly. That raises the usable port count. Two-tier capacity goes as the square of the port count, so it moves the tier boundary a long way.

Endpoint speedBreakoutUsable ports
800G none 144
400G 2:1 288
200G 4:1 576
100G 8:1 1,152

Roles and optics

Coding matters more than it looks. A switch may refuse a transceiver that is not coded for it, and that is one of six axes that have to agree before a link comes up. The others are form factor, reach, fibre type, fibre connector and ferrule polish. See optics compatibility.

Notes

XDR generation, 115.2 Tb/s. Verified: 144x800G over 72 OSFP cages in 4U, air-cooled. High radix collapses tier counts — NVIDIA states a 2-tier fat tree reaches 10,368 NICs, which matches this tool's calculation exactly. Power figures remain unverified.

Source: NVIDIA XDR switch hardware user manual (networking-docs.nvidia.com/xdrswitcheshw), verified 2026-08. Ports, cages, and rack units confirmed; power figures are NOT. Needs verification 2026-08-06

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