The NVIDIA/Mellanox Cable is an 400Gb/s twin-port OSFP to 400Gb/s twin-port OSFP InfiniBand NDR Direct Attached Copper cable. Using the Octal Small Formfactor Plug (OSFP) and contains four high-speed electrical copper pairs, each operating at data rates of up to 100Gb/s. This cable is compliant with OSFP MSA (Multi-Source Agreement) and IEEE 802.3cd standards.
DACs offer the lowest latency, so are widely used in data centers to connect servers and GPU compute systems to the top-of-rack (TOR) switches and link spine-to-super-spine switches inside racks over short cable lengths. DACs are also used to create InfiniBand storage fabrics with hard-disk-drive (HDD) and flash memory subsystems.
Featuring a simple design and minimal components with Flat-top (OSFP-RHS) form factors, DAC cables offer the lowest-cost, lowest-latency, and near-zero-power connections for high-speed links. They enhance port bandwidth, density, configurability, and reduce power requirements in supercomputers and hyperscale systems.
Note："Finned-top" transceivers are now called "Integrated Heat Sink" (IHS) as the cooling fins are integrated into the OSFP connector metal top. Commonly used in air-cooled switches. "Flat-top" transceivers are now called "Riding Heat Sink" (RHS) as the cooling fins ride on top of the network card or systems internal cages. This is used for both air-cooled and liquid-cooled applications for DGX, ConnectX-7 and BlueField-3 DPUS.
