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SFP+ Direct Attach Cable Wiki

Today, 10G SFP+ direct attach cable (DAC) becomes cloud computing and cloud storage mainstream primary connection tool, but what is a direct attach 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 + direct attach cable is and its other details, as well as discuss the advantages and disadvantages between active and passive SFP + DAC cable.

What Is 10G SFP+ Direct Attach Cable (DAC)?

The 10G SFP+ direct attach cable option is defined for 10G applications over copper cable. The 10G SFP+ DAC link utilises 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+ direct attach cable, and hosts are defined in the SFF-8431 specification developed by the SFF Committee, with broad industry participation.

10G SFP+ direct attach cable 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 utilising an optical transceiver on each and every end as well as a length of fibre 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+ direct attach cable 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.

10G SFP+ direct attach cable

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

Vendors provide both active and passive versions of the 10GSFP+ direct attach cable. 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 direct attach cable can make it a possibility to support longer and thinner cable assemblies. The lower priced approach is the passive direct attach cable, 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+ direct attach cable is much less costly but require the host to do the work of driving it properly.

Benefits:

  • Lower Costs
  • Higher Reliability

Tradeoffs:

  • No LOS
  • No TX Disable
  • No Interrupts
  • Limited Management Interface
  • Host must drive Cu cable

Active 10G SFP+ direct attach cable provides the added benefit of being “optical-module” like.

Benefits:

  • Enhanced Signal Integrity
  • Longer Cable Lengths
  • Transmit Pre-emphasis
  • Active/Adaptive Receive Equalization
  • Tx Disable
  • Loss of Signal (LOS)
  • Interrupts
  • Management Interface
  • Looks like an optical module
  • Don’t have to worry about host Tx/Rx for Cu cables

Tradeoffs:

  • More Expensive
Summary

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+ direct attach cable of various compatible brands from here.

Related Article:  10GBASE-LRM vs. 10GBASE-LX4, Which One Wins?

Direct Attach Cables For 10 Gigabit Ethernet Application

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The dramatic growth of bandwidth requirements has led to the increasing worldwide use of higher-performance servers. This in turn has led to the expanding need for 10 Gigabit Ethernet(10GE or 10GbE or 10 GigE), refers to various technologies for transmitting Ethernet frames at a rate of 10 gigabits per second (10×109 or 10 billion bits per second), is rapidly gaining traction within data centers. The IEEE 802.3ae standard permits distances between physical locations up to 40 kilometers over a single-mode fiber. Both single-mode and multi-mode fiber systems can be used with 10 GbE applications.

10GbE supports both copper and fiber cabling. However, due to its higher bandwidth requirements, higher-grade copper cables are required: category 6a or Class F/ cat 7 cable for links up to 100m. Unlike previous Ethernet standards, 10 gigabit Ethernet defines only full duplex point-to-point links which are generally connected by network switches. Half duplex operation and hubs do not exist in 10GbE.

Over the years, improvements in 10GbE technology, price, and performance have extended its reach beyond enterprise data centers to midmarket networks, they confidently deployed 10GbE in their corporate backbones, data centers, and server farms to support high-bandwidth, mission critical applications.

There are many 10 Gigabit Ethernet relevant products available, and the direct attach cable(DAC) is one of them. Direct Attach Cables are widely applied in storage, data, and high-performance computing connectivity. They are used to connect one Mobility Access Switch with another when forming a stack.

Important Of Direct Attach Cable:

DAC is supported only on 10G ports. Do not insert a DAC into a 1G port;

Do not attempt to unplug the integrated copper cable from the transceiver and insert a fiber cable into the transceiver.

Common direct attach cables include SFP cables, SFP+ cables, XFP to XFP cables, QSFP+ cables, MIni SAS cables, CX4 cables. These direct attach cables can meet the ever growing need to cost-effectively deliver more bandwidth, and they can be customized in different length to meet your requirement.

10G SFP+ Cables

Small form-factor pluggable plus transceiver (SFP+) direct attach copper cables, also known as Twinax cables, are suitable for short distances up to 23 ft (7 m), making them ideal for highly cost-effective networking connectivity within a rack and between adjacent racks. 10G SFP+ Cable connects from one SFP+ slot to another, without the need for SFP+ transceivers. The Direct-Attach cable is terminated on both ends with mechanical connectors that plug directly into SFP+ slots the same as SFP+ transceiver modules to. The cable is fully passive, it does not have signal buffers or amplifiers. 10G SFP+ Cable is an economical solution for interconnecting 10 Gigabit Net Optics products, also great for making short 10 Gigabit connections between network optic product and server, network switch, and monitoring equipment that have SFP+ slots.

Direct attach cable assembly is a high performance integrated duplex data link for bi-directional communication. Have a wide selection of direct attach cables at FiberStore, there always has one meets your demand.