Do Son 
Direct Attach Cables (DACs) are usually fixed-length cable assemblies with fixed connectors at both ends, and non-replaceable ports, and the module head and copper cable cannot be separated. Widely used in storage area networks, data centers, and high-performance computing connectivity. DACs are more and more popular with users due to their significant advantages such as high-cost performance, high performance, high speed, high recombination, and low loss. The demand for it in the market is increasing.
Structure of DAC cable:
Using silver-plated conductors and foamed insulated core wires as materials, wire pair shielding and total shielding are adopted to form a high-speed cable. High-speed cables have excellent attenuation performance, low delay, and anti-interference, and can realize high-frequency broadband transmission. There are 30~24AWG specifications and various structures such as 2P, 4P, or 8P, which can be used in a variety of different applications.
Classification of DAC cable:
- 10G SFP+ to SFP+ DAC
The 10G SFP+ to SFP+ DAC uses passive twin axial cable assemblies and connects directly to SFP+ modules, featuring high density, low power, low cost, and low latency.
- 40G QSFP+ to QSFP+ DAC
The 40G QSFP+ to QSFP+ DAC provides a cost-effective way to establish 40G links between the internal rack and cross-rack QSFP+ switch ports, enabling access layer uplinks to core backbone links to 40G/100G, It is widely used in the high-speed backbone network, enterprise network switching and network storage due to its high speed and low latency.
- 40G QSFP+ to 4*SFP+ DAC
One end of the QSFP+ to 4*SFP+ DAC is a 40G QSFP+ interface, which meets the requirements of SFF-8436, and the other end is four 10G SFP+ interfaces, which meet the requirements of SFF-8432. To meet the requirements of the length of the end cable, a splitter is added in the middle of the MPO cable, so that one 40G optical signal can be divided into four 10G signals, which is the most economical and simple way to implement switch port to exchange.
- 25G SFP28 to SFP28 DAC
25G SFP28 to SFP28 DAC can provide customers with 25G high-bandwidth data interconnection capability, which conforms to IEEE P802.3by Ethernet standard and SFF-8402 SFP28, and is widely used in data center or supercomputing center system scenarios.
- 100G QSFP28 to QSFP28 DAC
100G QSFP28 to QSFP28 DAC can provide customers with 100G high-bandwidth data interconnection capability, providing 4 duplex channels, each channel can support up to 25Gb/s operating rate, and the aggregation bandwidth is 100Gb/s, in line with the SFF-8436 specification, used in Connection between devices with QSFP28 ports.
- 100G QSFP28 to 4*SFP28 DAC
100G QSFP28 to 4 SFP28 DAC has a 100G QSFP28 interface on one end and 4 25G SFP28 interfaces on the other end, which can provide customers with 100G high-bandwidth data interconnection capability, in line with SFF-8665/SFF-8679, IEEE 802.3bj, and InfinibandEDR standards, It is widely used in data center or supercomputing center system scenarios.
DAC connection scheme in the data center rack:
(1) High-speed cables are used for short-distance direct connection between data center racks, and the length is generally 1 to 10 meters.
(2) AOC active optical cable can be selected for short distances within 5 to 30 meters.
(3) Optical module + fiber jumper combination can be selected for long distances above 30 meters.
The QSFPTEK high-speed interconnect DAC cable product line includes SFP+, QSFP+, QSFP+ to SFP+ Breakout, QSFP28, QSFP28 to SFP28 Breakout. All of them are suitable for point-to-point applications in the data center.