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.

Which Qsfp28 Transceiver Should You Choose And Why?


For any network engineer who wants to create a high-performance 100G network, the qsfp28 transceiver has become indispensable. The versatility of a 100g qsfp28 makes it a no-brainer because it complies with the 100Gbps ethernet standard as well as InfiniBand EDR specification. The qsfp 100g transceiver also works with devices from various manufacturers like Huawei, Cisco, and HPE. Let’s now break down the reasons why the 100g qsfp28 is now the go-to for people looking for low-powered, small-footprint transceivers.

Qsfp28 Transceiver Types And Supported Standards

There have been many challenges that have faced developers of high-speed 100G transceivers. This has led to many great devices gaining popularity and shortly afterward fading away because of the inability to meet certain industry requirements. However, the qsfp28 transceiver has become a constant feature of high-speed 100G networks. This is partly due to its numerous use cases, small form factor, and acceptable power requirements.

The 100g qsfp28 transceiver family is huge and one of the features that distinguish various iterations is transmission mode. There are broadly four categories including single-mode, multi-mode transceivers, active optical cable (AOC) and direct attach cable (DAC). Amongst the affordable connectivity options is multi-mode, Active Optical Cable, and DAC transceivers. However, this comes at a cost of transmission distance because they are only good up to 100 meters. Single-mode cables are costlier but can move data much further as can be seen in deployments using qsfp 100g er4 s.

There are as well many versions of the 100g qsfp28 transceiver module as we shall now find out.

The common types of qsfp28(including sr4,lr4,er4,zr4)
The common types of qsfp28

Short- to medium-haul qsfp28 transceiver types

Qsfp 100g sr4: Back To Basics

This is not a single brand but rather a networking standard developed by IEEE. The 100Ggbase sr4 transceiver makes use of 8 fibers in multi-mode configuration for transmitting data bi-directionally over the 850nm spectrum. The 100g qsfp28 sr4 can transmit data up to 70 meters over the OM3 interface and up to 100 meters OM4 when the selected interface is MTP. The ideal connectivity solution for these modules is 12-fiber OM3/4 cables using MTP.

Qsfp 100g lr4: Going The Distance

The distance challenge has always existed when it comes to networking capabilities. To improve over the previous transceiver model, the IEEE published the 100G qsfp28 lr4 standard. This iteration is primarily concerned with increasing the range of transmission beyond 100 meters and it is rated for up to a 10-kilometer transmission distance. It achieves this with the fiber optic link in single-mode. To achieve this the 100gbase lr4 uses four wavelengths in the 1310nm range to transmit data. It also uses WDM as well as a duplex LC interface to increase transmission efficiency.

Intermediate-range qsfp28 transceiver modules

Apart from the above-mentioned modules, there are several other transceivers ideal for short-distance deployments. One noteworthy module is the 100G qsfp28 DAC which is the most cost-effective option for deployments not exceeding 5 meters. This module has two main direct attach cables including qsfp28 to sfp28 DAC and qsfp28 to qsfp28 DAC.

For slightly longer transmission, the 100g qsfp28 psm4 can move data up to 500 meters with single-mode fiber using the MTP interface. The benefit of this module is that it is a lot more affordable compared to the 100G base lr4 module. For transferring data up to 2 kilometers, the 100g qsfp28 cwdm4 is ideal.

Long-haul Qsfp28 Transceiver Options

Many companies require to transmit data over very long distances. Two mainstream transceivers can fulfill these requirements. The first one is the qsfp28 er4 which uses single-mode fiber to transmit data up to 30 kilometers. When coupled with FEC it can send data over 40 km with normal LC connectors.

The second alternative is the very long-distance qsfp28 zr4 which uses single-mode fiber as well. This module is equipped with a duplex LC connector and transmits over the 1310 nm wavelength. Its transmission distance can reach to 80km.

ApplicationData CenterData CenterDCIDCI、Metro

Factors to consider when choosing qsfp28 transceiver

For a while now, the gold standard for 100-gigabit ethernet connectivity is the qsfp28 transceiver. However, several modules comply with this standard. So, which product should a network engineer use for their particular deployment? To answer that, several factors come into play as we shall now delve into.

Cabling Distance

When the transmission distance is short (below 5 meters), a network can be easily served with a passive direct attach cable. These include qsfp28 to 4xsfp28 as well as qsfp28-qsfp28 direct attach cables. Due to the short transmission distance, these DAC’s comfortably do the job of 100g optical modules without sacrificing performance. As an added benefit, the DAC option comes in cheaper than the optical 100g qsfp28 transceiver. The passive qsfp28 DAC cables are excellent for distances between 1 and 5 meters.

QSFP28 to SFP28 passive DAC | QSFPTEK
QSFP28 to SFP28 passive DAC | QSFPTEK

Multi-mode Cables Between Switches

For 100-gigabit ethernet networks using multi-mode fiber to connect switches, there are two possibilities. The first option is suitable for cables running between 3 and 20 meters and it is the qsfp28 active optical cable. The second possibility is the 100g qsfp28 sr4 optical module attached to a 12-pin patch cord with either OM3/4 interface. In this type of setup, data can be transmitted up to 100 meters.

Single-mode Cables Between Switches

Transmission distance is the single biggest differentiator between various 100g qsfp28 modules. The intermediate distance of between 100m and 2km is most relevant for large data centers. At this distance, cost-effectiveness is key and that is where the qsfp28 CRL4/CWDM4, as well as qsfp28 psm4 modules, come into play. Under 500 meters, the best option is the PSM4 when coupled with 8 single-mode cables in parallel. To reach two kilometers, the CRL4 coupled with single-mode optic cable strikes the perfect balance between performance and cost while maintaining high reliability.


Long-distance Single Mode Optic Fiber

To create even longer 100G connections, a more capable qsfp28 transceiver is required. According to IEEE standards, the ideal transceiver for the job is the 100gbase-lr4 module that has an LC interface. This setup is suitable for networks spanning up to 10 kilometers.

Despite the numerous types of transceiver modules for short- to long-haul Ethernet networks, optical fiber cables are indispensable. High-speed cables are ideal to save cost for shorter distances but optical cables reign supreme for longer distances. QSFPTEK can offer all the above types of 100g transceivers. If you have any questions about transceivers, you can always get in touch with QSFPTEK.Inc staff via