DAC · Direct Attach Copper
A copper cable carrying high-speed signals over short reach, cheaper than optics for in-rack and adjacent links.
Current numbers
~20 kW/rackpower saved by passive DAC copper scale-up vs optical transceivers in-rack
passive ~1-2 mcopper reach at 800G/1.6T: passive DAC ~1-2 m, active (AEC) ~3-7 m; optics beyond — the domain-size wall
~1–7 mcopper reach budget at 800G: passive DAC ~1–2 m, active AEC ~3–7 m, optics beyond — caps physical topology