direct attach cable (GbE) (DAC)

Direct Attach Cables(DAC) are copper cables used in HV data transmission. DAC cables are pre-assembled twinaxial cables terminated on both sides with transceiver modules. They can be used to transmit data rates of several gigabits per second.

Copper-based direct-connect cables are a cost-effective alternative to optical cables, the Active Optical Cables( AOC). The differences lie in the distance that can be bridged, the data rate, and in possible irradiation. With DAC cables, a distinction is made between passive and active DAC cables. With passive DAC cables, the line ends are terminated with the transceiver module. In contrast, active DAC cables have an amplifier component connected in front of the transceiver module. Therefore, distances of up to 5 m can be bridged with passive DAC cables, and up to 100 m with active ones. And this with data rates of 10 Gbit/s and 40 Gbit/s. The wire diameter for both versions is between 24 AWG and 30 AWG. In contrast, optical AOC cables can bridge distances well over 100 m, depending on the optical fiber. Distances of 2 km can be bridged with single mode fibers and SiP transceivers.

Direct Access Cable (DAC) with SFP transceiver module, photo: cbo-it.de

Copper-based and optical direct access cables are used in data centers for cabling switches ToR switches, MoR switches, EoR switches as well as neighboring racks and servers. Depending on the data rate, SFP+ modulesand SFP+ modules for 10 Gigabit Ethernet and QSFP+ modulesand QSFP+ modules for 40 Gigabit Ethernet are used as transceiver modules.