The NVIDIA/Mellanox InfiniBand Cable is an 800Gb/s twin-port OSFP to two 400Gb/s twin-port OSFP Direct Attached Copper dual breakout cable. The 8-channel twin-port OSFP end uses a IHS/finned top form-factor for use in Quantum-2 and Spectrum-4 switch cages. The two 400G ends support 4-channels of 100G-PAM4 (400G) This cable is compliant with OSFP MSA (Multi-Source Agreement) and IEEE 802.3ck 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, 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 system's internal cages. This is used for both air-cooled and liquid-cooled applications for DGX, ConnectX-7, and BlueField-3 DPUS.
