With the growing network requirements for higher network speed, greater scalability, higher performance and reliability, 40G network gradually becomes a better choice for most data centers. Under this condition, the 40G QSFP+ copper direct attach cable (DAC) came into market, which is designed for delivering an aggregate data bandwidth of 40Gb/s in a short distance and high density cabling interconnect system. As a highly cost-effective solution for 40G to 40G or 10G to 40G connection, there is no doubt that the QSFP DAC twinax cable plays an important role in 40G cabling for better meeting the increasing requirements.
QSFP DAC Twinax Cable Overview
QSFP DAC twinax cable is also referred to as QSFP+ copper direct attach cable or QSFP copper cable, used for connecting switch to switch or switch to sever. It can be simply divided into three types, QSFP+ to QSFP+ direct attach copper cable, QSFP+ to 4 SFP+ direct attach breakout copper cable and QSFP+ to 4 XFP breakout copper cable. Since the first two types of QSFP DAC twinax cables are more commonly used, the following will mainly talk about these two kinds of QSFP DAC twinax cables.
As for the QSFP+ to QSFP+ direct attach copper cable, it generally consists of a length of copper twinax cable and two QSFP+ connectors, used for 40G to 40G connection, which is capable of distances of up to 10 meters. As for the QSFP+ to 4 SFP+ direct attach breakout copper cable, it is designed for 10G to 40G short reach applications up to 5 meters. Compared to the previous copper cable, it is more complicated, fitted with one QSFP+ connector on one end of the copper twinax cable and four SFP+ connectors on the opposite end of the copper twinax cable.
We used to choose fiber optic transceiver and patch cable to deploy the fiber link, which requires us to firstly insert the transceiver to the switch and then connect the patch cable to the transceiver. However, for the QSFP DAC twinax cable, it can be directly plugged into the switch to finish the 40G connection, without any transceiver, as shown in the following figure. In short, the QSFP DAC twinax cable is really a cost-effective solution for interconnecting high speed 40G switches to 40G switches or 40G switches to existing 10G equipment.