What is SFP+ Direct Attach Copper Cable(DAC)?


In today’s market, Direct Attach Cables (DAC)provide an excellent pre-terminated and factory assembled & tested solution for both copper and fiber optic cabling in data centers. It is a kind of optical transceiver assembly widely applied in storage area network, data center, and high-performance computing connectivity etc. The DAC cables are used to connect one mobility access switch with another when forming a stack.


Direct-Attach Cables (DAC) are cost efficient close-range interconnection media widely used in telecom operator equipment rooms, data centers and corporate networks for connecting LAN and SAN equipment in same or neighboring racks. Our multi-vendor compatible Direct-Attach Cables portfolio support full range of transmission speeds from 10 Gbps up to 100 Gbps applications, customizable length of cables and current most popular interface assembly form factors – QSFP and SFP. Our multi-vendor compatible Direct-Attach Cables portfolio is compatible with 80% of networking equipment, where is not implemented a special algorithm for protection against third party modules. However – we can provide Direct-Attach Cables with custom-encoded firmware in order to make it work almost in any equipment and we can support encoding of each end to support different vendor equipment, allowing using Direct-Attach Cables as cross-platform interconnection medium.


SFP+ direct attach cable (DAC) is a fixed assembly that is purchased at a given length, with the SFP+ connector modules permanently attached to each end of the cable. SFP+ DAC provides high performance in 10 Gigabit Ethernet network applications, using an enhanced SFP+ connector to send 10 Gbps data through one paired transmitters and receivers over a thin twinax cable or fiber optic cable. The 10G SFP+ Cable is designed to use the same port as an optical transceiver, but compared with optical transceivers, the connector modules attached to the cable leave out the expensive optical lasers and other electronic components, thus achieving significant cost savings and power savings in short reach applications.


SFP+ DAC is a low cost alternative to traditional fiber and twisted-pair copper cabling in data center deployments. SFP+ DAC provides better cable management for high-density deployments and enhanced electrical characteristics for the most reliable signal transmission


Passive and Active 10G SFP+ Direct Attach Cable (DAC)

SFP+ Direct Attach is known as the successor technology to 10GBASE-CX4. SFP+ Direct Attach, as implied in the name, uses SFP+ MSA and by using the inexpensive copper twinaxial cable with SFP+ connectors on both sides, provides 10 Gigabit Ethernet connectivity between devices with SFP+ interfaces. SFP+ Direct Attach has a 10 meter distance limitation, thus the target application is interconnection of top-of-rack switches with application servers and storage devices in a rack.

Passive cables are much less expensive but require the host to do the work of driving it properly.


  • Lower Costs
  • Higher Reliability
  • Lower Power Consumption
  • Plug and Play Simplicity

Fewer Components (No Active Tx /Rx Components)

Only Capacitors, Resistors, EEPROM, Cable



  • Reduced Cable Flexibility
  • Reduced Modularity
  • Limited Distance
  • No LOS
  • No TX Disable
  • No Interrupts
  • Limited Management Interface
  • Host must drive Cu cable


Active cables offer the benefit of optical-module.


  • Enhanced Signal Integrity
  • Longer Cable Lengths
  • Transmit Pre-emphasis
  • Active/Adaptive Receive Equalization
  • Tx Disable
  • Loss of Signal (LOS)
  • Interrupts
  • Management Interface



  • Higher price


Fiber-Mart supplies various kinds of high speed interconnect DAC cable assemblies. All of our direct attach cables can meet the ever growing need to cost-effectively deliver more bandwidth, and can be customized to meet different requirements. For more information, pls visit www.fibermart.com. pls not hesitate to contact us for any question:service@fiber-mart.com




Direct Attach Cable(DAC) VS Active Optical Cables(AOC)

As one kind of optical transceiver assembly, Active Optical Cables (AOC) and Direct Attach Cables (DAC) are a alteration of optical transceiver, they are used to connect switches with one another when creating a stack or switches to routers or servers.

A Direct Attach Cable (DAC) can be produced as passive or active. As the passive DAC has no active components, it offers a direct electrical connection between corresponding cable ends. This method can also be completed by an active DAC, which is considered active because there are extra electronics embedded inside the connectors. Therefore it helps to advance signal quality, offering a longer cable distance. The DAC is a fixed assembly that can be bought in several lengths for short distances of up to 15 Meter.They are suitable for short distances, making them ideal for highly cost-effective networking connectivity within a rack and between adjacent racks.

AOC cable is always active. It has two types of connectors combined with fixed optical fibers with a similar function as optical transceivers. In respond to the demand for a higher data bandwidth, active optical cable (AOC cable) has came into being to satisfy different cloud computing applications. Active optical cable is a term used to describe a cable that mates with standard electrical interfaces. The electrical-to-optical conversion on the cable ends is adopted to enhance the transmission speed and distance of the cable without sacrificing compatibility of standard electrical interfaces.

Both DAC and AOC have their particular advantage and disadvantage.

Growth of fiber technology, someone may believe that copper technology is obsolete. This is not accurate for direct attach copper cables. Indeed, a direct attach copper cable still has its advantages:

With the growth of copper cable technology, in Today’s market,DAC can support higher data rates than old copper interfaces—from 4Gbps to 100Gbps per channel.  reduce the overall power consumption and heat dissipation, which help network operators save cost.DAC cables are similar and hot swappable just like fiber optic modules. Supporting such multiple protocols from Gigabit to 100G Ethernet,Direct Attach Cables (DAC) are a cost effective solution compared to optical transceivers.

DAC cables have the potential to Another factor is that DAC cable is robust and does not need patch panels or additional cables when connected to devices, as is the case with an optical module. The modules on both ends make them sturdy and reliable as well as space-saving.


Though there are a few disadvantages of using direct attach cables: One of it is that direct attach (DAC) copper cables are more thick and massive than AOC cables, making it difficult to be managed. Additionally, since the electrical signals are used, direct attach copper cables are susceptible to the effects of electromagnetic interference (EMI), such as unwanted responses, degradation, or complete system failure.

AOC provides more advantages, such as lighter weight, high performance, low power consumption, low interconnection loss, EMI immunity and flexibility.


AOCs are a substitute to optical transceivers which exclude the detachable interface between transceiver modules and optical cables. It offers a number of advantages over direct attach copper (DAC) cables. due to its material, AOC weighs less than a DAC cable. optical fiber uses light signals, AOC is immune to electromagnetic interference. the disadvantage of AOC is that it may be a slight more expensive for customers.

Whatever believe it or not, Nothing can be perfect, so do the DAC cables. Although they can save space and cost for data center managers, the drawbacks still exist. As the main element of DAC cable is copper, it is heavy and bulky. the more important, if DAC cables are deployed in high volume, the cable diameter and cable stiffness are another problem that should be considered. In this case, active optical cables (AOC cables) seem to be a better choice, for they are made of thinner and more pliable optical cable.

Fiber-Mart supplies various kinds of high speed interconnect DAC & AOC cable assemblies including 10G SFP+ Cables, 40G QSFP+ Cables, and 120G CXP AOC Cables. All of our cables can meet the ever growing need to cost-effectively deliver more bandwidth, and can be customized to meet different requirements. For more information,pls visit www.fibermart.com. if you have any requirements , pls not hesitate to contact with us service@fiber-mart.com