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.

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.

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

 Features

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.

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.