In simple terms, a DAC has modules at either end of a ~26-28 AWG twinax copper cable that allows direct communication between devices over copper wire. Both ends have specific connectors and the cable length is fixed. Electromagnetic shielding around the copper cable increases as the speeds increase to keep communication reliable.
As part of our fiber optic guide series, we are mostly focusing on optics. Optical communication is essential for the long-range transmission of data. As networks get faster, and we push into the 400GbE era and beyond, the distance that copper communication can reliably and practically travel at those speeds is limited. For the next few years, we are still likely to see copper DACs between devices in a single rack, but going forward, most rack-to-rack and beyond connectivity will happen via optical communication.
In this example, we have two QSFP+ connectors on either end. There is then a fixed cable that goes between the two ends allowing devices to communicate. This cable, unlike optical transceivers, is usually a fixed length and limited in maximum length by signal integrity.
40G QSFP+ Passive DAC Cable (QSFP+ to QSFP+)
Post time: Mar-15-2023
