25G SFP28 Transceiver Module Overview

Updated on Mar 6, 2021 by

With the evolution of 5G technology and pursuit for higher speeds in enterprise data centers, equipment providers are responding with 25Gbps edge devices that require more bandwidth than can be provided on a traditional 10Gbps interface. 25G SFP28 transceivers are the critical player among them. They come in various types that cover different transmission distances.

25G SFP28 Transceiver Type and Applications

Following are the main categories of 25G SFP28 transceivers: 25G SFP28 standard transceiver, 25G BiDi SFP28 transceiver, and 25G WDM SFP28 transceiver.

Category Type Reach Cable Type Application
25G standard SFP28 transceiver 25G SR 100m OM4 MMF 25GBASE-SR Ethernet
25G LR 100m SMF Data Center Backbone; High-speed Servers
25G ER 40km SMF High-speed storage area networks; CPRI 10
25G BiDi SFP28 transceiver 25G BiDi 10km SMF 25GE LR; eCPRI & CPRI
25G WDM SFP28 transceiver 25G CWDM 40km SMF 25G GE LR; eCPRI , CPRI; High-speed Servers; High-performance Computing Clusters
25G DWDM 10km SMF 25G Ethernet Data Center Networks; CPRI/eCPRI 5G Fronthaul Networks
25G LWDM 40km SMF 25GBASE-ER Ethernet Data Center Networks; CPRI/eCPRI 5G Fronthaul Networks

25G Standard SFP28 Transceiver Module

SFP28 SR - “SR” refers to short range. It is mainly used with OM4 multimode fiber to transfer data over a short distance (up to 100m).

SFP28 LR - “LR” refers to long range. It is mainly used with OS2 single mode fiber for long distance transmission (up to 10km).

SFP28 ER - “ER” refers to extended range. It is used with OS2 single mode fiber can realize at most 40km transmission.

They can be plugged into data center, campus and service provider switches and routers to provide high speed 25Gbps connectivity.

25G BiDi SFP28 Transceiver Module

25G BiDi SFP28 transceiver is different from the common 25G SFP28 transceiver. It uses one port to transmit and receive signals over a single strand fiber and must be used in pairs. It adopts two optical signals of different center wavelengths, for example, 1270nm-TX/1330nm-RX at one end and 1330nm-TX/1270nm-RX on the other end. BiDi SFP28 transceivers realize bidirectional transmission of optical signals on one optical fiber, thus saving fiber resources and leading the next generation of 5G communication technology.

25G WDM SFP28 Transceiver Module

25G WDM SFP28 transceiver consists of 25G CWDM SFP28 transceiver, 25G DWDM SFP28 transceiver and 25G LWDM SFP28 transceiver, all of which are commonly used in 5G front-haul networks.

25G CWDM SFP28 transceiver is a single mode CWDM transceiver for duplex optical data communications at a nominal wavelength of CWDM (1271~1331nm). CWDM transceiver is designed for short-range communications and is mainly used for city and access networks. Moreover, 25G CWDM SFP28 solution can well solve the current 5G millimeter wave pre-transmission problem.

25G DWDM SFP28 transceiver is designed for 25G Ethernet and CPRI/eCPRI links over SMF where wavelengths are packed tightly together in order to increase bandwidth over existing fiber networks.

25G SFP28 LWDM transceiver presents as a low-cost solution among 25G WDM transceivers, for it adopts relatively cheap DML lasers to keep a stable transmission, making it an ideal and efficient solution in 5G front-haul transmission. The module can also save fiber resources by achieving the multi-channel signals transmission on one single fiber.

25G SFP28 Transceivers FAQs

What is the maximum supported distance for 25G SFP28 transceivers?

The maximum currently supported distance for 25G is 40km using SFP-25G-ER transceiver module. Additional optics may be released in the future to support longer distances.

Are 25G SFP28 transceivers of different brands interoperable with each other?

It depends on the SFP28 standards with which the 25G transceivers are compliant. As long as the 25G SFP28 transceivers meet the associated industry standard specifications,they are fully interoperable.

Can I use SFP28 transceivers in SFP+ ports?

Optical transceivers support the fixed speed as they are manufactured. The link could be down when using SFP28 transceiver for SFP+ link.

For some devices with 25G ports that are also 10G capable, FS recommends the 10/25GBASE-SR transceiver module with 25Gbps and 10Gbps dual rate, supporting connectivity options for 25G Ethernet, 10G Ethernet and data center. For more information, please refer to the 10/25GBASE-SR module.

Can I use SFP+ transceivers in SFP28 ports?

Theoretically, the answer is yes. The link speed is limited to 10Gbps though.

Can I connect SFP28 ports with QSFP28 ports?

Yes, it is available by configuring the QSFP28 100G transceiver to work at 4*25G breakout mode, and use the supported hardware to connect SFP28 ports with QSFP28 ports, such as QSFP28 to SFP28 DAC/AOC breakout cable or MTP-LC breakout cable with one 100G QSFP28 optical module is used on one side and four 25G SFP28 optical modules used on the other side as the following figure shows.


25GbE transceiver is a critical carrier to implement 25G Ethernet technology in cloud and enterprise data center environments. As the enhanced version of SFP+, 25G SFP28 transceiver is able to handle 25Gbps per lane transceiver while ensuring backward compatibility to SFP and SFP+.

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