NVIDIA offers only crossover optical fiber cables based on 4-channels of 100G-PAM4 only using MPO-12/APC optical connectors. These cables are specific to the 100G-PAM4 NVIDIA offering for NDR InfiniBand and Spectrum Ethernet. Linking up to five transceivers directly together over short reaches without intermediate optical patch panels is standard practice for accelerated AI accelerated systems.
NVIDIA fiber cables are crossover, Type-B fibers that enable directly linking two transceivers together. This enables directly connecting transceivers together and aligning transmit lasers with receiver photodetectors by crossing over the fibers pin arrangement inside the cable with both optical connectors. For example, pin 1 in transmit laser side is crossed over to pin 12 in the receive transceiver’s photodetector side optical connector.
NVIDIA’s fiber cable offering includes:
Straight, single mode, crossover fibers up to 100m, and 1:2 splitter fibers up to 50-meters.
Straight and 1:2 splitter multimode crossover fibers up to 50-meters.
These fibers are available from NVIDIA and designed and qualified specifically for NVIDIA systems with the highest quality and tolerances.
NVIDIA does not offer fiber cables based on:
MPO-12/UPC or MPO-16/APC or LC duplex.
Non-crossover, Type-A parallel straight or splitter fiber cables, trunk cables, 2-fiber single mode LC cables, and crossover fibers longer than 100-meters.
NVIDIA recommends sourcing these from numerous third-party suppliers.
Crossover fibers
Fiber splitter 1:2 cables using three connectors with 4-channels for the twin-port OSFP transceiver end and two 2-channel ends for single port transceivers are offered for 3m to 50-meters in both single-mode and multimode. Twin-port OSFP transceivers use two 1:2 splitter cables for an effective 1:4 split to 4x200G.
Length is measured from optical connector end faces.
Split points are 0.2-meters from the single optical connector face.
Optical connector keys – small bumps on top of the connector ends are used to orient the fiber to the transceiver and align the fiber 1 to laser 1, etc.
Bend radius of the fibers is 3mm.
Split point is 0.2m from connector end face.
All NVIDIA-supplied fiber cables are female on both ends –- pins are on the transceivers.
NVIDIA-supplied, Straight and Splitter Fiber Cables
Straight and Splitter Fiber Cables in Twin-port OSFP, OSFP, and QSFP112 Transceivers
The reaches specifications used with NVIDIA transceivers (50m, 100m, 500m, and 2kilometers) are calculated assuming two optical patch panels are used in the link and assuming each employ 2 optical connectors each, for a total of 4 optical connectors. Transceivers are tested in the factory with this worst-case configuration. Complex cabling infrastructures or lengths longer than specified with multiple optical connectors in the link should have the link budget calculated to ensure sufficient light can reach the end points.
When Type-A, parallel fiber trunk cables are used, at least one segment should have a crossover Type-B cable in the link to align lasers with photodetectors. For lengths longer than 100-meters, we recommend the customer sourcing high-quality third-party single-mode fiber cables for parallel MPO-12/APC and LC based cables. Attention must be paid to connector pins and holes and fiber polarity to align transmit lasers with receive transceiver photodetectors.
A single crossover Type-B cable can be used with multiple Type-A straight fiber cables The end goal is to align pin 1 of the transmit laser transceiver to pin 12 of the photodetector in the receive transceiver.
Using three NVIDIA supplied, crossover fiber cables will not work as the fiber cables have holes for alignment pins on both ends and need to mate with another cable pins on connector ends.
Two Connector Junctions or Two Patch Optical Panel Links for NVIDIA Tested Transceivers Using Type-A and B Cables
MPO-12/APC Alignment Holes and Pins
