Decoding Four types of 100G QSFP28 Transceiver

With the development of IP-based multimedia service, especially video service, network traffic has been continuously rising. As a result, 40G and 100G have emerged as the key technologies capable of supporting the growth in network bandwidth. After a lengthy period of hype, 40G technologies have finally widely been deployed. And now it is 100G’s turn. While 100G networking may seem excessive to many right now, there are many industries where that 100G speeds are quickly becoming necessary. This post will introduce four QSFP28 transceiver types that are commonly used in 100G data center.


QSFP-100G-SR4 or 100GBase-SR4 QSFP28 optical transceiver is a full duplex, photonic-integrated 100G module, which uses 4 fibers for transmit and 4 for receive, with each lane supporting 25Gbp, providing an aggregated data rate of 100Ggps as shown below on up to 70m of OM3 MMF and to 100m of OM4 MMF. Like 40GBase-SR4, 100Gbase-SR4 uses a MPO 12 cable with 4 strand for transmit and 4 for receive, allowing for existing 40GBase-SR4 fiber assemblies to be reused when higher performance is needed. This interface standard has been introduced alongside the 100G QSFP28 offerings now, arriving on the market in order to make any 40GbE to 100GbE upgrade as seamless as possible.

QSFP28 sr4


QSFP-100G-LR or 100GBase-LR4 QSFP28 is another 100G standard, which focuses on longer data transmission up to 10km over single-mode fiber. Like 40GBase-LR4, the 100GBase-LR4 is also a multilane optic. However, each lane’s data rate is increased to 25Gbps. It has duplex LC interface and uses WDM technologies to achieve 100G dual-way transmission over four different wavelengths around 1310nm that can be seen in the image below.

qsfp28 lr4


Targeted to service the need on a parallel single-mode infrastructure, QSFP28 PSM4 module is a low cost solution to long reach data center interconnect. It uses four parallel fibers (lanes) operating in each direction, with each lane carrying a 25G optical transmission as shown below. Interfaced with MPO connector, it can support distance up to 500 meters over single-mode fiber, which covers a wide rage of applications in data center.

qsfp28 psm4


Backed by the CWDM4 MSA Group, QSFP28 CWDM4 is a 100G interface that address data communication links up to 2km in the data center. The CWDM4 architecture employs 4 lanes of 25Gbps using CWDM technology to transport 100G optical traffic across duplex LC single-mode fiber. Compared to 100GBase-LR4, CWDM4 is an alternative for long transmission distance in data center. The working principle can be seen in the following image.

qsfp28 cwdm4


100G Ethernet is no longer a fantasy, and it is on the way. QSFP28 is a key to the 100G deployment. In the part above, we have introduced four types QSFP28 modules widely used in 100G network. All of these modules that have been tested and are 100% compatible can be purchased in FS.COM. If you have any related requirement, kindly visit FS.COM.


1 thought on “Decoding Four types of 100G QSFP28 Transceiver

  1. Hi,

    I’m unable to understand why exactly is LR4 more expensive than CWDM or SR4 transceivers (for a standard form factor, let’s say it’s QSFP28 here)?

    Many Thanks,


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