Today, 10G SFP+ Direct Attach Copper (DAC) cable becomes cloud computing and cloud storage mainstream primary connection tool, but what is DAC cable? For this, different manufacturers of DAC cable have different presentations and descriptions. And here, we’ve got a number of related information together, mainly to discuss what exactly SFP + DAC cable is and its other details, as well as discuss the advantages and disadvantages between active and passive SFP + cable.
The 10G SFP+ DAC option is defined for 10G applications over copper cable. The 10G SFP+ DAC link utilizes a receive equalizer from the host PHY/SerDes to be able to compensate for the Inter Symbol Interference (ISI) introduced by the cable. Electrical and mechanical specifications for SFP+ optical modules, 10G SFP+ DAC, and hosts are defined in the SFF-8431 specification developed by the SFF Committee, with broad industry participation.
10G SFP+ DAC is made from the inexpensive copper twinaxial cable with SFP+ connectors on both sides based on SFP+ MSA (multi-source agreement). It uses SFP+ connectors for 10G links instead of utilizing an optical transceiver on each and every end as well as a length of fiber optic cable. It takes away the expensive optical lasers along with other electronic components. For both active and passive 10G SFP+ DAC cables, a smaller electrical component is used to recognize the SFP+ module and cable type to the Ethernet interface. 10G SFP+ DAC is known as the successor technology to 10GBASE-CX4. It has the advantages of low power, low cost, low latency with the more benefits of having the small form factor of SFP+, and thinner, more flexible cabling compared with 10G SFP+ transceivers. Due to the distance limitation, the target application of 10G SFP+ DAC is interconnection of top-of-rack switches with application servers and storage devices in a rack.
Vendors provide both active and passive versions of the 10GSFP+ DAC. 10GSFP+ SFP+ DAC assembly is recognized as active in case there are signal processing electronics in the SFP+ module to increase signal quality and supply a longer cable distance. So the active DAC can make it a possibility to support longer and thinner cable assemblies. The lower priced approach is the passive DAC, which has a tendency to be shorter. Active 10G SFP+ DAC has a 10m distance limitation and passive 10G SFP+ DAC ranges from 1 m to 7 m. But you may discover variations in supported cable lengths among different vendors.
Passive 10G SFP+ DAC are much less costly but require the host to do the work of driving it properly.
- Lower Costs
- Higher Reliability
- No LOS
- No TX Disable
- No Interrupts
- Limited Management Interface
- Host must drive Cu cable
Active 10G SFP+ DAC provide the added benefit of being “optical-module” like.
- Enhanced Signal Integrity
- Longer Cable Lengths
- Transmit Pre-emphasis
- Active/Adaptive Receive Equalization
- Tx Disable
- Loss of Signal (LOS)
- Management Interface
- Looks like an optical module
- Don’t have to worry about host Tx/Rx for Cu cables
- More Expensive
This low-cost 10G SFP+ DAC is beneficial, as an example, for interconnecting a collection of switches, as well as for short-distance connections between switch ports and Ethernet interfaces on servers as well as other devices. Before the growth and development of 10GBASE-T, it was the only real low-cost copper connection designed for 10 Gbps operation. For active and passive 10G SFP+ DAC, each has advantages and disadvantages. You can select according to your special needs. You can also get 10G SFP+ DAC of various compatible brands from here.
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