InfiniBand NDR/XDR Cabling Standard_

NVIDIA reference design · BICSI

• Confirm the rate: NDR = 400 Gb/s per port (4 lanes × 100G PAM4); XDR = 800 Gb/s per port. Quantum-2 QM9700/9790 expose 32 physical OSFP cages carrying 64 NDR 400G ports via twin-port OSFP.
• Select media by reach, in this order of preference: passive DAC for in-rack (≤~1.5 m), active copper (ACC) for adjacent racks (≤~3–4 m), AOC for short rows, transceiver + MMF (MPO) for structured fiber, single-mode for long backbone runs.
• Switch-side NDR OSFP is twin-port (2×400G) and finned for air cooling; host-side ConnectX-7 / BlueField-3 OSFP is single-port and flat-top (liquid/cold-plate adjacent). Do not mix the two form factors on the wrong end.
• Build the port map and patch schedule before pulling a single cable — rail-optimized or fat-tree, every host port to its leaf port, documented.

TIA-568 · MPO Method A/B/C

• Standardize on one MPO polarity method fabric-wide (Method B is common for parallel optics). Mixing methods is the #1 cause of dead links that test clean on a fiber scope.
• NDR SR4 / DR4 breakouts use MPO-12 (APC for single-mode, UPC where specified) — verify key-up/key-down orientation on every adapter.
• Match connector grade to link type: angled-physical-contact (APC) for single-mode to control return loss; UPC for multimode. Never intermix APC and UPC in a channel.
• For OSFP transceivers, confirm the correct optic for the run (SR4 multimode ≤~50 m, DR4/FR4 single-mode for longer) — reach mismatch shows up as marginal links under load, not at install.

IEC 61300-3-35

• Clean-inspect-connect, every endface, no exceptions. Scope to IEC 61300-3-35 zone criteria (core/cladding/adhesive/contact) and pass before insertion.
• Re-inspect after every mate-demate; a single insertion against a dirty bulkhead can scratch a good connector.
• Use the correct cleaner for the connector (MPO vs LC, APC vs UPC) and dry-then-wet only as needed; cap unmated connectors immediately.
• Reject and re-terminate any endface failing the zone thresholds — do not 'clean twice and hope.'

BICSI · OEM bend-radius spec

• Hold the minimum bend radius: never below the cable's rated minimum (commonly ~10× outer diameter for patch fiber; tighter only if the cable is explicitly rated). Violated bend radius = elevated insertion loss and long-term fiber fatigue.
• Separate power and fiber pathways; maintain service loops at both ends for moves/adds/reseats without re-pulling.
• Dress with hook-and-loop, not zip ties, on fiber and high-count bundles — over-cinched zip ties crush jackets and shift loss.
• Preserve airflow and serviceability clearances; bundles must not block tray extraction or cold-plate quick-disconnects.

TIA-606-C / ANSI-J-STD-607

• Label both ends of every cable to a single TIA-606-C scheme: source-rack/port → destination-rack/port, machine-printed, not handwritten.
• Build the as-built cable map during the install, not after — every link recorded with its endpoints, media type, and test result.
• Capture transceiver serial / part numbers per port for warranty and RMA traceability.
• Deliver the labeling scheme key with the as-built so the next crew can read it cold.

Acceptance test plan (ATP)

• Fiber: insertion-loss and return-loss test (and OTDR on structured runs) against the channel budget for the link type; record per-link results.
• Bring up the fabric: verify 100% ports link at the rated speed (NDR 400G / XDR 800G), no auto-negotiation fallback to a lower rate.
• Watch for symbol errors and link flap over a soak window — a link that comes up but accumulates errors fails acceptance.
• Validate end-to-end with NCCL / perftest bandwidth across the domain; confirm per-link throughput sits in the expected range before sign-off.