Introduction of 100GBASE LR4

In recent years, the need to link information in the world has become more necessary than ever. Especially during the outbreak of the Covid pandemic and most companies have switched to working remotely. Building a data center capable of transmitting information quickly and accurately is a top requirement.

100G Ethernet is becoming mainstream, the demand for 100G optical modules is increasing, and nowadays 100G optical modules account for a large part of the network construction cost. Accordingly, the concept of 100GBASE-LR4 is also increasingly popular.

Figure: QSFP28-100G-LR4

Introducing the 100GBASE-LR4 standard

The 100GBASE-LR4 standard is defined by IEEE. It is an Ethernet interface to transmit frames with a huge capacity up to 100 Gigabit Ethernet (100GbE) over 10 km of conventional SMF. 100GBASE-LR4 is one of the fastest growing Ethernet interfaces available today. The wavelengths used by the 100GBASE-LR4 are in the O band (1260-1360 nm). These four wavelengths are called DWDM or LAN-WDM wavelengths. To achieve 100 Gbps data rates, each of the four wavelengths of the 100GBASE-LR4 carries a 25 Gbps signal. The 100GBASE- LR4 can be used anywhere with the single-mode jumper already on hand.

QSFP28 LR4 working principle
Figure: QSFP28 LR4 working principle

Specifications of the IEEE 100GBASE-LR4 Optical Interface

  • Optical interface: Single mode
  • Maximum distance: SMF 9/125 cable: 6.2 miles (10 km)
  • Transmitter wavelength per lane:
    • Lane 0: 1294.53 to 1296.59 nm
    • Lan 1: 1299.02 to 1301.09 nm
    • Lan 2: 1303.54 to 1305.63 nm
    • Lan 3: 1308.09 to 1310.19 nm
  • Average launch force per lane: –4.3 to 4.5 dBm per lane; The maximum total number of discharges is 10.5 dBm
  • Average receiving power per lane: –10.6 to 4.5 dBm
  • Receiver saturation per lane: 4,5 dBm
  • Receiver sensitivity per lane: –10,6 dBm

How many types of 100GBASE-LR4 transceivers are there?

The 100GBASE-LR4 optical module is not limited to one physical form factor as many are available, e.g. CFP, CFP2, CFP4, CXP and QSFP28. However, QSFP28 is the most popular type and most commonly used for 100GbE or 100G connections in general. Many companies like CISCO, Juniper and HPE – Aruba, Fortinet have implemented this in new hardware releases. In this article, I will focus on the overview of the 100GBASE-LR4 QSFP28 optical transceiver module, as it is the most commonly used.

Introduction of QSFP28-100-LR4 QSFP28 Optical Transceiver Module


Some outstanding features of the 100GBASE-LR4 QSFP28

  • Hot pluggable QSFP28 MSA form factor
  • Compliant to IEEE 802.3ba 100GBASE-LR4
  • Up to 10km reach for G.652 SMF
  • Single +3.3V power supply
  • Operating case temperature: 0~70 oC
  • Transmitter: cooled 4x25Gb/s LAN WDM EML TOSA
  • Receiver: 4x25Gb/s PIN ROSA
  • 4x28G Electrical Serial Interface (CEI-28G-VSR)
  • Maximum power consumption 4.0W
  • Duplex LC receptacle
  • RoHS-6 compliant

100GBASE-LR4 QSFP28 transforms 4 input channels of 25 Gbps into 4 channels of LAN WDM optical signals. It then synthesizes these 4 channels of optical signals into a single channel for 100G optical transmission. On the receiver side, the process will be done in reverse, the final output is 4 output channels of electrical data. The center wavelengths of the 4 WDM LAN channels are 1295.56, 1300.05, 1304.58 and 1309.14 nm, respectively. They are also members of the WDM LAN wavelength mesh defined in IEEE 802.3ba.  The 100GBASE-LR4 QSFP28 transceiver has outstanding performance for 100G applications up to 10 km over SMF cable and optical interface. It complies with IEEE802.3ba 100GBASE-LR4 requirements.

How does QSFP28 LR4 work?

The 100G QSFP28 LR4 optical module creates a 100G optical transport channel by aggregating four WDM LAN optical signals which it converts from 4 input 25G signals. At the receiving end, this process is done again in the opposite direction, that is, it will scatter the 100G optical signal into 4 WDM LAN optical signals and finally convert it into 25 Gbps electrical data.

Connecting and connecting QSFP 100G LR4 cable

Enterprises and data centers are using 10Gb/s and 40Gb/s networks for 100Gb/s connectivity. QSFP 100G LR4 is widely applied in the cases of direct connection of 100G long distance and interconnection.

QSFP28 LR4 Module 100G-100G Direct Connection
Figure: QSFP28 LR4 Module 100G-100G Direct Connection

Direct connection 100G to 100G

The easy way to get a direct 100G connection is not too different from the 10G/40G method. You just need to plug two 100G QSFP28 LR4 optical modules into the respective ports on the switch. Then you connect them using LC fiber cable.

FAQ about QSFP 100G LR4 optical module

Q1: Does QSFP 100G LR4 Module work if connected to CFP 100G LR4 on the other end?

A: Yes, QSFP 100G LR4 will work if connected to 100G LR4 CFP optical module because these 2 types of optical module have the same baud rate of 100G, they are also working on the same wavelength (1310nm).

Q2: Is it necessary to clean the optical connector of the transceiver? How can we clean the QSFP28 LR4 100G optical module?

A: Dust or contamination can accumulate on transceiver terminals and cause problems such as reduced discharge power. To ensure a better connection, we strongly recommend that you clean both connectors every time you disconnect and reconnect them.

Q3: Will using compatible QSFP 100G LR4 optics in my device negatively affect the manufacturer’s warranty?

A: It won’t. Network hardware manufacturers will not require user to use only branded optics. In fact, when a product failure or failure occurs in the network and the failure or failure is not caused by useing a 3rd-party transceiver, they will continue to support the affected product under warranty or within their support program.

Q4: Will the QSFP 100G LR4 optical module work on channel 1310 in 18 CH 1270-1610nm CWDM Mux/Demux or will the MUX require a separate 1310 channel?

A: Please note that this 100G QSFP LR4 1310nm optical module will not work on channel 1310 of 18 channels 1270-1610 CWDM Mux Demux, Mux requires a separate 1310 channel. If you select channel 1310, the following wavelengths cannot be used: 1270/1290/1310/1330/1350/1370nm.

Q5: Does QSFP28 100G LR4 optical module support custom service?

A: Yes, all QSFP28 100G LR4 optical modules are offered with customized service. All you need to do is provide us with your compatible brand and model type. And we appreciate any requests for customized products and solutions for your specific preferences and requirements.

transceivers for qsfp28 to sfp28 in 2021

Many people are searching for solutions that will enable them to interface qsfp28 to sfp28. One popular method you can use to achieve this goal is to use a qsfp28 to sfp28 adapter. You could also use a qsfp28 breakout cable from QSFPTEK. The qsfp28 to sfp28 adapter can enable you to migrate to 100 gigabit ethernet.

The big question on peoples’ minds is, “isn’t it better to buy a breakout or fanout cable?” What more benefits will a qsfp28 to sfp28 adapter give me? We will answer those questions and more shortly.

Qsfp28 to Sfp28 Adapter – Is It The Magic Bullet?

QSFP28 Adapter
QSFP28 Adapter

The adapter is a qsfp28 module that has a receptacle for connecting sfp28 connectors at the back. The adapter acts as a middleman between qsfp28 and sfp28 cables. You can connect an sfp28 module to this adapter and connect the adapter to a qsfp28 port to enable the transition between the two speeds.

This adapter is the best way to convert a qsfp28 port to accept sfp28 cables. Also, the adapter has an EEPROM id that enables you to connect the adapter to switches of various companies.

Unlike the operating temperature of common optical transceivers, the Qsa28 adapter can work in high-temperature servers. The operating temperature of this module is between -10 degrees and 85 degrees centigrade. This is a much wider temperature range than optical transceivers support.

Another benefit of the qsfp28 to sfp28 adapter is that it does not cause extra latency. It is because of the lack of signal processing that this adapter doesn’t add any delay in the signal.

The adapter can work in many ports including Qsfp28, qsfp dd, qsfp+, and qsfp56. You can also connect it to many types of cables including the SR sfp multimode cable, sfp multimode AOC cable, the lr sfp single-mode cable, and the base-t sfp converter.

Why Not Use A Breakout Cable Instead Of The Qsfp28 to Sfp28 Adapter?

The qsfp28 to sfp+ breakout cable is a cable with a qsfp28 connector on one end that splits into four sfp+ connectors on the opposite end. The breakout cable uses duplex serial connections to enable two-way communication on all four sfp+ ports. The breakout cable is a short-distance connector best suited for use within the same rack.

So, why not skip the qsfp28 to sfp28 adapter and use a breakout cable instead. Let us compare the two alternatives to determine the one best suited for the job. The key areas we will look at include performance, cost, and compatibility.

Qsfp28 to Sfp28 Adapter Cost

The qsfp28 to sfp28 adapter does not conform to the Multi-source Agreement (MSA). Only one company owns patent rights to this adapter. Because of this monopoly, the company charges other vendors a lot of money for the rights to produce the adapter. A qsfp28 breakout cable complies with the MSA standard. That means several manufacturers have permission to make the cable. The cable works with devices from other companies so long as they meet MSA standards.

The takeaway here is that the qsfp28 to sfp28 adapter is a lot more expensive than the qsfp28 breakout cable from QSFPTEK.

100G to 25G break out cable
100G to 25G break out cable

Qsfp28 to Sfp28 Adapter Performance

The adapter gives you the flexibility to connect any sfp28 connector to a 100Gb sfp port. The issue people have with the QSA28 adapter is that it currently supports 25G-100G speed. It means that when you use this adapter, you will downgrade the connection from 100 Gbps to 25 Gbps. You will not harness the extra 75 Gbps bandwidth when you use the qsfp28 to sfp28 adapter.

The breakout cable does not have this limitation. You can split a 100 Gbps connection into four 25 Gbps cables that work at full speed.

Qsfp28 To Sfp28 Adapter Compatibility

Because of the lack of MSA standard support, using a qsfp28 to sfp28 adapter will be hit and miss. It is because manufacturers of devices like switches and routers do not have to support the adapter. Some manufacturers break support with generic optical modules.

Power Consumption Of Qsfp28 to Sfp28 Adapter

The QSA28 adapter is a passive device. It receives the signal from the sfp28 module and passes it to the qsfp28 port. Since the adapter does not process the signal, it does not consume any power. A breakout cable consumes power to work.

Things To Keep In Mind About The Adapters and Breakout Cable

  • To ensure the connection between the qsfp28 port and sfp28 connector works, you must enable fanout mode on the host device. You should also know that not all devices support fanout mode, so consult the manual.
  • You can connect an sfp28 module to a qsfp28 port using the adapter. But, you cannot connect a qsfp28 module into an sfp28 port.
  • The communication industry is quickly changing. Sometimes it will be cheaper to buy high-speed equipment to be able to keep up with the changing market rather than resorting to intermediary measures.
  • The technology behind qsfp28 to sfp28 breakout cables has advanced rapidly. Thus, the breakout cables are guaranteed to work on any host device. Even if a host device manufacturer uses vendor lock-in, a compatible breakout cable from QSFPTEK will work on the device.


If you are migrating from a 100g port to 25g connections, you can use either the breakout cable or adapter. However, after considering the performance of the cables, compatibility across host devices, and cost, there is only one winner. The breakout cable comes out on top regardless of the challenge.

You can use the qsfp28 to sfp28 adapter as an intermediate step before installing breakout cables. There is a big probability that you will need to recover the unused capacity that is created when using an adapter. QSFPTEK has a very high-quality qsfp28 to sfp28 breakout cable that works with many host devices. It is also very affordable compared to other brands. The quality of their cables is second to none. To get your hands on the best value breakout cable send an email to