Direct Attach Cable (DAC) is the cable that links the integrated duplex data transceivers for bi-directional communication, and the modules and cable can not be separated. It is designed for 10 Gigabit Ethernet, and is only available for 10G port. DAC can be classified into passive and active ones. The passive DAC only provides direct connection between cable ends, transmission through copper wire, while the active DAC can provide electronics within connectors, transmission through copper wire. Therefore, the active DAC has a higher performance than passive DAC.
Active Optical Cable (AOC) is a kind of cable linked to transceiver modules without connectors. The connection can not be separated, if the transceiver or cable needs to be changed, they should be removed together. It is an active DAC to provide electronics and optics within connectors, transmission through fiber.AOC has the advantage of a wider bandwidth which can reach up to 40Gbps with QSFP+, a lighter weight compared with direct attach copper cable and the electromagnetic (EMI) immunity. But the shortage of AOP is the expensive price in light of its cost.