Tag Archives: twinax cable

SFP+ Cable: How Much Do You Know?

Recently, the popularization of SFP+ cable has become the trend of data center interconnection. However, what is SFP+ cable? To this end, different SFP cable manufacturers have different presentations and descriptions. Here, let’s discuss the exact meaning and classification of SFP+ SFP+ cables.

What Is SFP+ Cable

SFP+ cable refers to the high-speed cable that are equipped with transceiver (without components, can only transmit signals) at both ends. It was widely used in storage area networks, data centers and high-performance computer connectivity. SFP+ cable supports 10G Ethernet, 8G Fiber Channel, 10G FCoE, 10G InfiniBand and various unified architecture link applications.

SFP+ Cable Types

Today, several types of SFP+ cables are accessible, such as SFP+ direct attach cables, and SFP+ active optical cables. In additional, there are two types of SFP+ direct attach copper cable: SFP+ active direct attach copper cable and SFP+ passive direct attach copper cable.

SFP+ Direct Attach Copper Cable

Also known as twinax cable, SFP+ direct attach copper cable is used in rack connections between switches and servers, containing a high-speed copper cable and two SFP+ copper modules. With the low cost and low power budget, the SFP+ direct attach copper cable has the advantage of high-end port density, configurability, and utilization. The cables are thermally removable and insertable, meaning that you can remove and replace them without turning off the switch or breaking the switch function.

SFP+ cable: SFP + Direct Attach Copper Cable

Figure 1: SFP+ Direct Attach Copper Cable

SFP+ Active Copper Cable: To enhance the signal and driven from the port without additional power requirements, SFP+ active direct attach copper cable assembly contains a low power circuit in the connector. As a low-cost alternative to optical transceivers, the active version is often used in row or intermediate row data center architectures for interconnection distances up to 15 meters.

SFP+ Passive Copper Cable: As a high performance connectivity solution, SFP+ passive direct attach copper cable assembly supports 10GB Ethernet and Fibre Channel applications. Besides, it has higher reliability and fewer components with lower cost.

There is no real visual way to distinguish the difference between active and passive twinax cables. The active or passive twinax cable assembly can be directly connected to the SFP+ shell. Active twinax cables have active electronic components in the SPF+ housing to improve signal quality; passive twinax cables are only a straight line “wire” without active components. Typically, a twinax cable less than 5 meters in length is passive and a cable longer than 5 meters is active, but this is a general rule, depending on the supplier. Most manufacturers will have some kind of marking on the cable connector head, which will mark the cable as active or passive.

SFP+ Active Optical Cable

With a full-duplex construction, SFP+ active optical cable can transmit data at 10Gb/s. In additional, it can support a single transmission between 1 and 100 meters. Supporting single-channel and high-speed data link applications, SFP+ active optical cable is fully compatible with Fibre Channel, and Ethernet. As a cost-effective interconnect solution, SFP+ active optical cable has the edge of high speed, longer cable length, and enhanced signal integrity.

SFP+ cable: SFP+ Active Optical Cable

Figure 2: SFP+ Active Optical Cable


It is no doubt that SFP+ cables have many advantages after a brief introduction to the three SFP+ cables. First, SFP+ cables are interchangeable and hot-pluggable, which means that when the device is working too early, you don’t have to completely shut down the system to replace the device. Second, it is compatible with other protocols such as Ethernet, Fibre Channel, and PON standards, maintaining the speed and integrity of the signal as it travels over long distances. Third, the SFP+ cable is not too expensive, making it more and more popular. FS.COM can provide you with the reasonably priced and high quality cables. By the way, we also has very excellent SFP modules. If you have any need or question about SFP+ cables, please contact us.

All You Need to Know about 56G QSFP+ to QSFP+ DAC Twinax Cable

DAC is the short name for direct attach cable. Currently, there are many different types of DAC twinax cables on the market such as SFP+ DAC Cable and QSFP DAC Cable. Terminated with transceiver-style connectors, they are designed to be used in the same ports as a typical SFP+ or QSFP transceiver, with no need for adaptors or converters, replacing two optical modules and a connectorized optical fiber with a twinax copper cable assembly. Here in this post, we will mainly focus on 56G QSFP+ to QSFP+ DAC Twinax Cable.

Basics on 56G QSFP+ to QSFP+ DAC Twinax Cable

The 56G QSFP+ to QSFP+ DAC twinax cable, as implied in the name, uses QSFP+ MSA and by using the inexpensive copper twinax cable with QSFP+ connectors on both sides, and provides 56 Gigabit Ethernet connectivity between devices with QSFP+ interfaces,which is suitable for very short distances and offers a highly cost-effective way to establish a 56 Gigabit link connectivity. Unlike 40G (10Gx4) QSFP+ DAC twinax cable, a kind of 40gb ethernet cable, the 56G QSFP+ DAC twinax cable is designed for 56G (14Gx4) InfiniBand FDR interconnecting networking applications such as high-performance computing (HPC), enterprise networking including top-of-rack switching and network storage markets.


The 56G QSFP+ DAC twinax cable is fully comply with QSFP+ Multi-Source Agreement (MSA) standards SFF-8436 and InfiniBand FDR specifications. And it is developed specifically as a cost-effective and lower-power alternative to 56G QSFP+ optics and 56G QSFP+ active optical fiber cable (QSFP+ AOC).

Specification and Features of 56G QSFP+ to QSFP+ DAC Twinax Cable

Now, many suppliers can provide 56G QSFP+ DAC twinax cable for customers. The key features and specification for these products are more ore less the same. Here, we take the generic compatible 56G QSFP+ DAC cable from FS for example.


specification for 56g dac

Key Features

  • Lower cost than 56G QSFP+ optics and active optical cable (AOC)
  • Maximum aggregate data rate: 56 Gb/s (4 x 14Gb/s)
  • Compliant with Infiniband QDR/DDR/FDR data rates
  • Hot-pluggable QSFP+ 38-PIN footprint
  • Low Insertion Loss and power consumption
  • Operating temperature range: 0 to 70°C


56G QSFP+ to QSFP+ DAC twinax cables are passive optic cables designed with high performance, low power consumption, long reach interconnect solution supporting 56G Ethernet. For suppliers like FS, their 56G QSFP+ to QSFP+ DAC and other twinax cable offer compatibility with a huge range of vendors, enabling the connectivity customers need within the Top of Rack and End of Row environments.