Category Archives: QSFP+ Transceiver

Differences Between 40G QSFP LRL4 and PLRL4 Modules


Data centers regularly undertake their own great migration, to ever-higher-speed networks. Since IEEE 802.3ba Ethernet standard introduced the 40 Gigabit Ethernet in 2010, 40G has been an unstoppable tendency in the future. At present, QSFP, CXP and CFP are three 40G transceiver module options. Among QSFP is the most common one. In terms of 40G QSFP modules, there are many different types available, such as QSFP-40G-CSR4, QSFP-40G-LR4, QSFP-40G-SR4, QSFP-40G-LRL4 and QSFP-40G-PLRL4 etc. We can see that QSFP-40G-LRL4 and QSFP-40G-PLRL4 look like similar. One difference is QSFP-40G-PLRL4 has a word “P”. So, what does this word mean? This passage will explain it and tell you some other differences between them.

In fact, QSFP PLRL4 refers to QSFP parallel LRL4. In general, digital data transmission can occur in two basic modes: serial or parallel. In parallel transmission, multiple bits are sent simultaneously on different channels within the same cable, or radio path, and synchronized to a clock. However, in serial transmission, bits are sent sequentially on the same channel which reduces costs for wire but also slows the speed of transmission. So 40G QSFP PLRL4 module uses parallel transmission which is achieved with MPO/MTP multifiber connectors. 40G QSFP LRL4 module uses serial transmission of which the connector is LC.


For these two modules both operate on 40GBASE-LRL4 standard, they actually both support link lengths of up to 1 kilometers over a standard pair of G.652 single-mode fiber. But besides the optical connectors they used, the wavelength and the interoperability of them are also different.

Wavelength (nm)

  • 40GBASE-LRL4 QSFP (Multiplexing and demultiplexing of the four wavelengths): 1270 nm, 1290 nm, 1310 nm, 1330 nm
  • 40GBASE-PLRL4 QSFP: 4 x 1310nm


  • For 40GBASE-LRL4 QSFP, the 40 Gigabit Ethernet signal is carried over four wavelengths. Multiplexing and demultiplexing of the four wavelengths are managed within the device.
  • For 40GBASE-PLRL4 QSFP, the 4x10G connectivity is achieved using an external 12-fiber parallel to 2-fiber duplex breakout cable, which connects the 40GBASE-LR4 module to four 10GBASE-LR optical interfaces. QSFP-40G-PLRL4 is optimized to guarantee interoperability with any IEEE 40GBase-LR4 and 10GBase-LR (in 4x10G mode).

All the comparisons between 40G QSFP LRL4 and PLRL4 modules above are listed in the following table. From this chart, you may get a more intuitive understanding.

Name Distance Wavelength Connector Interoperability
QSFP-40G-LRL4 1km (G.652) 1270nm, 1290nm, 1310nm, 1330nm LC 4-Channel CWDM Mux/Demux inside with SFP+ CWDM
QSFP-40G-PLRL4 1km (G.652) 4 x 1310nm MPO/MTP 4 x 10G operations on SMF with SFP+ LR

After reading this passage, you may know more about these two kinds of QSFP modules. Each one of them has their own features, which can satisfy different applications. You should choose the most suitable module for your use. has a large number of QSFP-40G-PLR4 and QSFP-40G-PLRL4 modules in stock with super quality and competitive price. You can visit that website to  choose your optics.

Related Article: 40G Transceiver Module: QSFP+ Module And CFP Module

How to Install a 40G QSFP+ Transceiver


1The 40G QSFP+ transceiver module is a hot-swappable, parallel fiber-optical module which has four independent optical transmit and receive channels. These channels can terminate in another 40G QSFP+ transceiver and can also be divided out to four separate 10G SFP+ transceivers. The QSFP+ transceiver module can operate on both copper and optical fiber cables. For example, QSFP-40G-SR4 module supports link lengths of 100m on OM3 multimode optical fiber and 150m on OM4 multimode optical fiber. Now, this 40G QSFP+ transceiver is mainly used in short reach applications in switches, routers, and data center equipment. As it provides higher density than 10G SFP+ transceivers, people are more likely to use this effective transceiver in these few years. But do you really know how to install a 40G QSFP+ transceiver? This article may offer you some specific guidances.

In general, there are 8 steps to install a 40G QSFP+ transceiver. As we all know, the QSFP+ transceiver module is a static-sensitive device. So, we always use an ESD wrist strap or similar individual grounding device when handling QSFP+ transceiver modules or coming into contact with system modules. Besides, the QSFP+ transceiver module can have either a bail-clasp latch or a pull-tab latch. In this text, installation procedures for both types of latches are offered. These 8 steps are as following:

Step 1: Attach an ESD wrist strap to yourself and a properly grounded point on the chassis or the rack.
Step 2: Remove the QSFP+ transceiver module from its protective packaging.
Step 3: Check the label on the QSFP+ transceiver module body to verify that you have the correct model for your network.
Step 4: For optical QSFP+ transceivers, remove the optical bore dust plug and set it aside.
Step 5: For transceivers equipped with a bail-clasp latch:
a. Keep the bail-clasp aligned in a vertical position.
b. Align the QSFP+ transceiver in front of the module’s transceiver socket opening and carefully slide the QSFP+ transceiver into the socket until the transceiver makes contact with the socket electrical connector. (Just do as the following picture shows.)

Step 6: For QSFP+ transceivers equipped with a pull-tab:
a. Hold the transceiver so that the identifier label is on the top.
b. Align the QSFP+ transceiver in front of the module’s transceiver socket opening and carefully slide the QSFP+ transceiver into the socket until the transceiver makes contact with the socket electrical connector.
Step 7: Press firmly on the front of the QSFP+ transceiver with your thumb to fully seat the transceiver in the module’s transceiver socket. (Just do as the following picture shows.)

Step 8: For optical QSFP+ modules, reinstall the dust plug into the QSFP+ transceivers optical bore until you are ready to attach the network interface cable. Do not remove the dust plug until you are ready to attach the network interface cable.

After reading this text, I hope you can get a clear understanding of how to install a 40G QSFP+ transceiver. If you want to know more about this 40G transceiver, you can visit Fiberstore which provides many tutorials about all kinds of fiber optic transceivers. And if you want to buy QSFP+ transceiver, I also recommend you to visit Fiberstore. The fiber optic transceivers they offered are always at low price and high quality.

Related Article: Optical Module Maintenance Methods and Installation Tips

Related Article: FS 40G QSFP+ Modules And DAC/AOC Cables Installation Guide

40 Gigabit Ethernet Options Guideline


When the IEEE introduced the 802.3ba Ethernet standard, this was in response to the increasing bandwidth demands facing data centers, paving the way for the introduction of 40Gb/s and 100Gb/s Ethernet operations. Believe it or not, the 40 Gigabit Ethernet era is already upon us. This text put together a brief overview of the current 40 Gigabit Ethernet optics types and form factors to aid in planning for future high-performance Ethernet needs.

40 Gigabit Ethernet Standards
The IEEE 802.3ba introduced the 40 Gigabit and 100 Gigabit Ethernet standards in 2010. 802.3ba is the designation given to the higher speed Ethernet task force which completed its work to modify the 802.3 standard to support speeds higher than 10 Gbit/s. This was the first time two different Ethernet speeds were specified in a single standard. The table below gives detailed specifications for 40 Gigabit Ethernet standards.

40 Gigabit Ethernet qsfp

40 Gigabit Ethernet QSFPTransceiver Options
As with any new generation of technology, one design goal was to leverage as much existing technology as possible. By minimizing the number of new interfaces, the interfaces become less expensive and take advantage of volume production and simplicity. To meet this design goal, there are three media modules will be used in the first generation of 40 Gigabit Ethernet: QSFP, CXP and CFP.

  • QSFP
    The Quad Small-Form-Factor Pluggable (QSFP) is similar in size to the CXP and provides four transmit and four receive lanes to support 40 Gigabit Ethernet applications for multimode fiber and copper today and may serve single-mode in the future. Another future role for the QSFP may be to serve 100 Gigabit Ethernet when lane rates increase to 25 Gbps.


  • CXP
    The CXP transceiver features 12 transmit and 12 receive 10-Gbps lanes to support one 100 Gigabit Ethernet port, or up to three 40 Gigabit Ethernet ports. It can achieve rates up to 120 Gbps of pluggable data over 12 lanes in one assembly while enhanced-footprint connectors transmit signals over 10 lanes for up to 100 Gbps.


  • CFP
    The C Form-Factor Pluggable (CFP) is a new media module that was designed for longer-reach applications, with up to 24 watts of power dissipation. Its dense electrical connectors and integrated, riding heat sink enable a range of interfaces. This module is used for 40GBASE-SR4, 40GBASE-LR4.


40GbE Cabling Options

The most common 40GbE cable is the QSFP+ Cable. Such as QSFP direct attach copper cable (DAC) and QSFP active optical cable (AOC). Besides, the MPO/MTP cable is considered the best solution for 40GbE. Since MPO/MTP connectors have either 12 fibres or 24 fibres array, which can allow data transmission across multiple fibres simultaneously.

  • Direct Attach Copper Cable

Transmitting 40 GbE over short distances of parallel coaxial copper cabling (also referred to as twinax cabling) is accomplished using a special cabling assembly with four lanes of coaxial cabling (eight pairs). Four pairs each transmit 10 Gbps in one direction and four transmit 10 Gbps in the other direction for a total data rate of 40 Gbps. The two common DACs used in 40g Ethernet are QSFP to QSFP and QSFP to 4 SFP+ copper direct-attach cables.


  • Active Optical Cable

In the market, there are two common 40g fiber cable: QSFP to 4 SFP+ breakout AOC and QSFP to QSFP AOC. The former is a 4×10 Gb/s parallel active optical cable which transmits four separate streams of 10 Gb/s data over ribbon cables in a point-to-multipoint configuration. The cable contains a QSFP+ module on one end and four separate SFP+ modules at the other ends. The latter is a 40 Gb/s parallel active optical cable which transmits error-free parallel 4×10 Gb/s data over multimode fiber (MMF) ribbon cables.


  • MPO/MTP Cable

Current multi-mode optics standards for 40GbE optics use multiple 10Gbps lasers, simultaneously transmitting across multiple fiber strands to achieve high data rates. Because of the multi-lane nature of these optics, 40GbE multi-mode optics use a different style of fiber cabling, known as MPO or MTP cabling. As with 10GbE optics over multi-mode fiber, an OM3 or OM4 grade MMF is needed to be able to cover longer distances. For 40g Ethernet, we can use 8 fibers MPO/MTP harness cables or 12 fibers MPO/MTP trunk cables. The former is to directly connect a QSFP port to other 4 SFP+ ports. The latter is to directly connect one QSFP port to another QSFP port.

MPO/MTP cable

Related articles:

40G Network Connectivity Solutions
MTP Fiber Cable Solutions
Three Types MTP Harness Cables Used in Today’s Data Center