Direct Attach Cable(DAC）is generally translated as direct cable, high-speed cable, passive copper core cable, etc. 40G QSFP+ DAC cable with fixed QSFP+ modules at both ends.

40G QSFP+ DAC stacking cable can be divided into 40G QSFP+ to QSFP+ cable and 40G QSFP+ to 4*SFP+ cable. And the 40G QSFP+ to QSFP+ cable is a 40G QSFP+ module at both ends, while the 40G QSFP+ to 4* SFP+ cable is a 40G QSFP+ module at one end, and the other end is 4 SFP+ modules.

The 40G QSFP+ to QSFP+ stacking cable is mainly used for the stacking connection of two 40G switch ports, while the 40G QSFP+ to 4*SFP+ stacking cable is used for the stacking connection of the 40G QSFP+ port and the 10G SFP+ port of the switch.

40G QSFP+ DAC stacking cable has the characteristics of low power consumption, high transmission stability, good confidentiality, anti-interference, large communication capacity, good heat dissipation, etc. Due to the relatively low cost of 40G QSFP+ DAC cable in the application of short-distance transmission, it is widely used in data center TOR.