Category Archives: Fiber Optic Tansceivers

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+ cable DAC 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.

How to convert QSFP to RJ45 for Network Connection

We know that in the present market, there are different types of ports for switches, such as RJ45 port, SFP+ port, QSFP port and etc. Generally speaking, the more ports a switch is equipped with, the more devices the switch can be connected to. Different ports enable switches to other devices via fiber or copper. So what are the different between these ports? How should we wire them respectively? How get different ports connected? Here in this article we will mainly focus on QSFP Port and RJ45 Port.

QSFP to RJ45: What Is QSFP Port

The QSFP port is to be inserted for 40 Gbps transceiver module that offers high-density 40 Gigabit Ethernet connectivity options for data center and high-performance computing networks. The QSFP transceiver module is a hot-swappable, parallel fiber-optical module with four independent optical transmit and receive channels. These channels can terminate in another 40 Gigabit Ethernet QSFP+ transceiver, or the channels can be broken out to four separate 10 Gigabit Ethernet SFP+ transceivers. The QSFP+ transceiver module connects the electrical circuitry of the system with either a copper or an optical external network.

40 gbps transceiver

QSFP to RJ45:What Is RJ45 Port

Unlike QSFP, which is used to support QSFP modules. RJ45, incidentally standing for registered jack 45, is the ubiquitous Ethernet style data port found on switches, routers and network cards. The RJ45 style connectors and ports are also commonly found on Ethernet, serial and ATM IMA cards and interfaces. However, the most common use by far is with Ethernet data connections from desktop PC network cards, Wi-Fi access points, data switches and routers in home and corporate networks. For twisted pair cables like cat5, cat6 and cat7 etc, they are all with RJ45 connectors.

RJ45 connector

Solution for QSFP to RJ45

Now we know QSFP and RJ45 are different ports which can be used by different transceivers. The QSFP spec is different from RJ45 spec. The former is to be prepared for QSFP modules, while the latter is designed to support GBIC, SFP and SFP + modules. So the to connect QSFP to RJ45 port cannot be achieved directly. Good news is that currently we’ve got product like QSFP+ to 4 x 10/100/1000BASE-T (RJ45) Breakout Cable. For this breakout cable, one connector is QSFP and the other connector is 4 x RJ45, thus we can easily get a connection between QSFP and RJ45.