QSFP28 SR4 Optical Transceiver Module Overview

Updated on Jan 5, 2022 by

100G qsfp28 transceiver

Currently, the surge of data volume has prompted the migration from 10G to 40G and 100G, thus enhancing great demands for 100G optical transceivers. The 100G QSFP28 optical transceiver module is the mainstream in the market due to its high port density, low power consumption, and reduced prices over the years. QSFP28 SR4, QSFP28 LR4, QSFP28 PSM4, QSFP28 CWDM4, and QSFP28 ER4 are the common types of the QSFP28 optical transceiver modules which are applied to meet different transmission distance requirements. Here, we are going to take a deep dive into the QSFP28 SR4 optical transceivers through the perspectives of definition, working principle, specifications, applications and FAQs.

QSFP28 SR4 Wiki

What Is QSFP28 SR4?

QSFP28 SR4 is a hot-pluggable full-duplex optical transceiver module designed for short-distance transmission in the 100G Ethernet network with a working bandwidth of 850nm. It has a smaller size than other 100G CFP/CXP modules and its power consumption is usually less than 3.5W. The 100G-QSFP28-SR4 module provides four independent transmit and receive channels and each lane can operate at 25Gbps up to 70m using OM3 fiber or 100m using OM4 fiber. Besides, QSFP28-100G-SR4 is fully compliant with the IEEE 802.3ba standard, as well as SFP28 MSA, SFF-8665, SFF-8636, RoHS, CPRI and eCPRI.

How Does QSFP28 SR4 Work?

The QSFP28 SR4 optical transceiver module transmits at the transmitting end and converts parallel electrical input signals into parallel optical signals by the Layser Array and then transmitted in parallel on the MTP/MPO multimode ribbon fiber. Upon reaching the receiving termination, the PIN array converts the parallel optical signals into parallel electrical signals.

QSFP28 SR4 Working Principle.jpg

Figure 1: QSFP28 SR4 Module Working Principle

FS QSFP28 SR4 Datasheet

All of FS QSFP28 SR4 optical transceiver modules are manufactured to satisfy the industry standard and have been recognized by numerous customers. They are proved to be compatible with over 200 vendors, such as Cisco, Juniper, Arista, Brocade, Dell and so on. Also, they are fully compliant with the QSFP28 MSA, IEEE 802.3ba 100GBASE-SR4 and IEEE 802.3bm CAUI-4 standard.

QSFP 100G SR4 Specification

Form Type QSFP28
Wavelength 850nm
Connector MTP/MPO-12
Cable Type MMF
TX Power -8.4~2.4dBm
Max Data Rate 103.1 Gbps
Max Cable Distance 70m (OM3) / 100m (OM4)
Transmitter Type VCSEL 850nm
DDM/DOM Supported
Receiver Sensitivity <-10.3dBm
Commercial Temperature Range 0℃ to 70℃ (32 to 158°F)
Protocols 100G Ethernet, MSA Compliant
Application 100GBASE Ethernet, Data Center, Campus

QSFP 100G SR4 Benefits

1. All FS QSFP 100G SR4 modules must run through programming and an extensive series of platform diagnostic tests to ensure its performance and compatibility. And FS 100GBASE-SR4 optical modules are fully interoperable with non-FS 100G SR4 transceivers as long as they meet the associated industry standard specifications.

2. With built-in high-quality chips, FS QSFP 100G SR4 transceivers cost ≤1.8W low power consumption, which makes it a cost-efficient option in your 100G deployment.

3. All QSFP 100G SR4 transceivers from FS are provided with exchange service within a year and five-year warranty policy to settle your concerns.

4. FS QSFP 100G SR4 modules can be reconfigured for any network hardware at a moment’s notice with the help of the transceiver coding tool - FS Box. In this way, the QSFP28 SR4 modules are programmed on-site to be compatible with over 200 OEM devices efficiently and flexibly.

5. With large stock in our US, AU, GE, RU, SG warehouse, QSFP28 SR4 100G modules can be shipped the same day after ordering.

QSFP 100G SR4 Cabling and Connectivity

Enterprises and data centers are outgrowing 10Gb/s and 40Gb/s networks for 100Gb/s connectivity. The QSFP 100G SR4 is in most cases the perfect fit in short-distance 100G direct connection and 25G-100G migration.

100G to 100G Direct Connection

The method to get a direct 100G connection doesn’t differ too much from that of 10G/40G. Simply plug two 100G QSFP28 SR4 modules into the corresponding ports on the switches, then connect them with either an OM3/OM4 MTP trunk cable (which depends on the reach you expect).

QSFP28 SR4 100G to 100G Direct Connection.jpg

Figure 2: QSFP28 SR4 Module 100G to 100G Direct Connection

25G to 100G Migration

Upgrading the network from 25G to 100G is a straightforward migration option. FS offers a gradual migration path with the support of the 100G QSFP28 SR4 transceiver and four 25G SFP28 SR transceivers, which are connected by an MTP harness cable.

QSFP28 SR4 25G to 100G Migration.jpg

Figure 3: QSFP28 SR4 Module 25G to 100G Migration


Q1: What is the difference between QSFP28 and 100G QSFP?

A: They are the same. The QSFP was originally defined for the speeds below 10G. When it was adopted for 40G, the name became QSFP+ to support the higher aggregate performance. After that, the QSFP was later adopted for 100G but the electrical interface had to be upgraded to handle 25Gbps/lane. The electrical interface for 100G can handle up to 28Gbps, hence the engineering and industry name is QSFP28.

Q2: What will happen if I plug in 100G QSFP SR4 transceiver that consumes greater than 3.5W?

A: All FS 100G QSFP SR4 ports are designed to handle QSFP28 SR4 transceivers that draw up to 3.5W. If a 100G QSFP draws greater than 3.5W, FS cannot guarantee the performance since there are other dependencies like airflow direction, ambient temperature, elevation, etc.

Q3: Can 100G QSFP28 SR4 interfaces interoperate with SR10 based 100GbE?

A: No. The 100G QSFP28 SR4 module has just 4 electrical lanes, which is not enough to support 10 lanes of 10G electrical interface. A 100G QSFP SR4 can only support a 4x 10Gbps or 4x 25Gbps electrical interface, which can be used as 4x 10GbE or 4x 25GbE, but not 10x 10GbE. As a result, the 100G QSFP SR4 cannot interoperate with SR10 based 100GbE transceivers.

Q4: Is it necessary to clean a transceiver optical connector? How to clean the QSFP28 SR4 100G transceivers?

A: Dust and contamination can accumulate on transceiver connectors and cause problems such as reducing the optic launch power. To ensure better connection, FS strongly recommends cleaning both connectors each time you disconnect and reconnect them. FS high-quality One-Push Fiber Optic Pen Cleaner for MTP/MPO connector is the best cleaning choice for 100GBASE-SR4 QSFP28 transceivers.

Q5: Will QSFP28 SR4 modules also work with 100G IB (EDR Infiniband)?

A: Yes, the QSFP28 SR4 optical transceiver module will work with 100G IB.

Q6: Does this optic support 4x25Gig mode with a breakout cable and using the "speed forced 25gfull" config command on the interface?

A: Yes. QSFP28 SR4 supports 4x 25Gig mode with a breakout cable and using the "speed forced 25gfull" config command on the interface.

Q7: Can the 100G QSFP28 SR4 module support the OTU mode (111.8Gbps) or 112G rate?

A: No, the 100G QSFP28 SR4 is a single rate module and it can only support 100G rate. CFP LR4, CFP ER4, and CFP2 LR4 modules are dual-rate modules and they can support 100G and 112G speed; there are 4x DFB lasers and each channel is 28Gbps speed.

Q8: Do FS QSFP28 100G SR4 modules support customized service?

A: Yes, all of FS QSFP28 100G SR4 transceivers are provided with customized service. All you need to do is to provide your compatible brands and model type for us. And we appreciate any inquiry for customized products and solutions for your specific preference and requirements.

Related Information

100G QSFP28 Optical Transceiver Comparison

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