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Optical Transceiver / 25/40/100/400G Transceiver / Taking an In-depth Look at 25G SFP28

Taking an In-depth Look at 25G SFP28

Posted on By FS.COM

Today’s enterprise data centers and networking environment are upgrading towards the trend of higher speeds, greater scalability, and higher levels of performance. The IT community used to define the upgrade path as from 10G to 40G to 100G. But new upgrade path is 25G–50G–100G with the advent of 25 Gigabit Ethernet (25GbE). How much do you know about 25G transceiver? Will 25G SFP28 dominate the market? Can you clearly tell from SFP28 vs. SFP+, SFP28 vs.QSFP+, SFP28 vs. QSFP28? This post will uncover the answers for you.

Basic Information of 25G Transceiver

SFP28 or 25G SFP+, as the enhanced version of SFP+, is designed for 25G signal transmission. Since its transmission rate can reach up to 28Gbps, it is so called as SFP28. The physical structure of the 25G transceiver is the same as the popular SFP and SFP+, but the electrical interface is upgraded to handle 25Gbps per lane. SFP28 can be divided into SFP28 SFP-25G-SR and SFP-25G-LR. The 25G SFP28 SR is designed to transfer data over short distance (up to 100m over MMF) while the 25G SFP28 LR transceiver set for long distance transmission (up to 10 km over SMF).


The Prospect of 25G Transceiver

With the emergence of 25 Gigabit Ethernet, various 25GbE products are provided by many vendors. For example, Mellanox had already shipped an end-to-end solution with adapters, switches and cables that support 25, 50, and 100GbE speeds. You may also heard “25G Ethernet Consortium”, a community joined by companies like Google, Microsoft, Broadcom, Cisco, Dell etc. So what’s the future of 25 Gigabit Ethernet? What about 25G SFP28?

According to the most recent Server-Class Adapter & LANon-Motherboard (LOM) Report from Crehan Research Inc., 25G gigabit Ethernet customer adoption is off to a much stronger start than either 10GbE or 40GbE. 25GbE shipments have handily surpassed two hundred thousand ports in just a little over a year, a milestone that took 10GbE about six years to reach and 40GbE about four (see the following figure). Moreover, each of these successive Ethernet networking technologies has ramped faster than its predecessor in response to changing data center networking traffic demands. Since 25 Gigabit Ethernet develops so fast, as one of the most important hardware for 25G gigabit Ethernet, 25g transceiver will also get a large share of the market.

25G Ethernet market trend

What Makes 25G SFP28 Transceiver Stand out From Other Modules?

What’s the difference between 25G SFP28 and SFP+, QSFP+, QSFP28? Which transceiver is the best choice to build Ethernet network for future use? Content below will show you answer by comparing SFP28 with SFP+, QSFP+, QSFP28.

SFP28 vs SFP+: Same Form Factor for Higher Bandwidth but Lower Cost

SFP28 utilizes the same familiar form factor as SFP+. However, SFP+ is designed to operate at 10.3125 Gb/s whereas SFP28 is designed to operate at 25.78125 Gb/s. A report told 25G server Ethernet adapters provides much lower unit pricing per 10G of bandwidth. Compared to 10G, 25G offers 2.5 times the bandwidth, but the price is not 2.5 times. The report also predicted that 25G adapter and 10G adapter will eventually charge for the same price by 2019. That means you will get every 10G of bandwidth at less than half of the price if you upgrade to 25G server adapters. The same is true for 25G SFP28 and 10G SFP+. And SFP28 has increased bandwidth, superior impedance control and less crosstalk than the SFP+ solution. All in all, the main advantages of SFP28 over SFP+ can be summarized in two points: lower cost and higher bandwidth.

SFP28 vs QSFP+: Cost-efficient Way for Upgrading

One key feature or advantage of SFP28 is that it operates on the standard of a single-lane 25Gbps (1x25G). While QSFP+ transceivers, designed to support 40G Ethernet, have evolved from 4x1G lanes (QSFP) to 4x10G lanes. Compared with SFP28, the underlying technology for QSFP+ is simply four lanes at 10G speed. It does not offer the advantages of cost, power consumption and server rack density. Deploying SFP28 to build 25GbE networks enables organizations to significantly reduce the required number of switches and cables, and the reduction of facility costs related to space, power and cooling compared with 40GbE, providing a more cost-efficient space for achieving next-generation 50G (2x25G ) and 100G (4X25G).

SFP28 vs QSFP28: One for 25G, the Other for 100G

QSFP28 stands for Quad Small Form-Factor Pluggable 28. It is the third generation of the QSFP interconnect systems designed for 100G performance compliant to the IEEE 802.3bj specification. Unlike SFP28, which is based on the SFP+ form-factor, QSFP28 is based on the 100G QSFP28 MSA form factor, having same design concept of QSFP optical transceiver. As it has been mentioned before, SFP28 modules support 25Gb/s over a single lane (1x25G), while QSFP28 supports four channels of high-speed signals with data rates ranging from 25 Gbps up to potentially 40 Gbps, and will meet 100 Gbps Ethernet (4x25G).


It is undeniable that 25G is the Next Generation data center rate option. 25 Gigabit Ethernet leverages the single-lane 25G physical layer technology to support 100G Ethernet, offering higher speed, lower power consumption and lower cost. If you are considering to build 25 Gigabit Ethernet network, reputed suppliers like FS.COM can offer a variety of SFP28 that are compatible to brands like Cisco, Brocade, IBM, Arista, Juniper, Intel and Mellanox etc. All these transceivers are of the same quality as the original one with a much lower price.

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